ispiv: A Pathfinder

This is a computer-generated pathfinder created against the Distant Reader study called ispiv.

Each Distant Reader study carrel is composed of many individual items. Each item is bibliographically described with author, title, date, summary, and keyword values. Below is a list of the items' most signficant keywords as well as lists of the items themselves. Purpusing the content of this pathfinder provides the student, researcher, or scholar with one way to get their heads around the scope of the carrel. The keywords include:

Velocity; Particle; Piv; Pressure; Field; Data; Image; Time; Surface; Camera; Uncertainty; Cylinder; Jet; Method; Measurements; Wall; Layer; Wake; Wind; Water; Model; Laser; Turbine; Angle; Phase; Particles; Tracking; Size; Wing; Correlation; Force; Streamwise; Spanwise; Sphere; Drag; Ice; Cavity; Droplets; Sea; Foam; Dpi; Barchan; Shuttlecock

Depending on how this pathfinder was created, many of the bibliographic sections will include elaborations on the meaning(s) of the given keywords. These elaborations were generated by feeding the items' summaries to a large langauge model and asking the model to address the question, "What is X?", where "X" is the keyword. The result will be a few sentences of elaboration. Be forewarned. The elaborations are often plausible, but they should not be take as truth. Instead, they should be taken as points for consideration.

• Effect of Gust Wind on Flow over a Wall-Mounted Fence by Bhamitipadi Suresh, Dhanush; Aju, Emmanuvel Joseph; Zaksek, Matthew John; Leffingwell, Melissa Marie; Jin, Yaqing (2021) - To further highlight the variation of local flow velocities, the corresponding Probability Density Function (PDF) distribution of wind velocities are presented in figure 5b-d. Specifically, in the very near wake region (x/h = 1), the PDF presents two distinctive peaks, corresponding to the flow velocities before and after the wind gust (figure 5b). While wind velocities within the upper region present distinct variation after the gust with dual peaks in PDF distribution, this is not the case within the wake flow (figure 6); here, the PDF distribution of wind velocities presents a sole peak for y/h≤ 1. Keywords: fence; figure; flow; gust; velocity; wake; wind
• The Stereo-PIV investigation of the unsteady flow in the draft tube of a model hydro turbine by Litvinov, Ivan ; Sharaborin, Dmitry; Shtork, Sergey ; Dulin, Vladimir ; Alekseenko, Sergey ; Oberleithner, Kilian (2021) - = pi(t)−(1/4)∑ 4 i=1 pi(t) for the cases of flow rates 0.5Qc (off-design) and Qc (BEP regime). This may lead to the formation of unsteady flow regimes featured by vortex instability of the swirling flow behind the runner, known as the precessing vortex core (PVC) Dörfler et al. (2012). Keywords: 0.5qc; flow; pressure; turbine; velocity
• Examining the Effects of Fluid Velocity Gradients on 4D Digital Holographic PIV/PTV Measurements by Xia, Yuan Jing; Sun, Bihai; Ahmed, Asif; Soria, Julio (2021) - Figure 1: Diagram of simulated digital holographic PIV/PTV setup The error introduced by velocity gradients within the interrogation volume is studied by simulating particles in a velocity field, with a given constant velocity gradient super- imposed on a uniform flow from which a time-series of hologram pairs are generated and the 3C-3D velocity fields and their errors are determined using 4D-DHPIV/PTV Sun et al. (2020). This study investigates how velocity gradients related to different flow regimes and their magnitudes affect 3-component–3-dimensional (3C-3D) digital holographic PIV measure- ment uncertainty. Keywords: gradients; ptv; velocity
• Stereo PIV measurements of oscillatory plasma forcing in the cross-plane of a channel flow by Hehner, Marc T.; von Deyn, Lars H.; Serpieri, Jacopo; Pasch, Saskia; Reinheimer, Timo; Gatti, Davide; Frohnapfel, Bettina; Kriegseis, Jochen (2021) - 1 Introduction Control of wall-bounded flows is a broad topic at which many numerical investigations were focused on friction-drag reduction in turbulent channel flows (see review Quadrio (2011)) that can be achieved by streamwise traveling waves (StTWs) of spanwise wall velocity (Quadrio and Ricco (2011), Gatti and Quadrio (2016)). As an intermediate summary, the sPIV results have demonstrated that the compliance of the velocity data in viscous units, from estimation of uτ by the total stress, and the DNS of Hoyas and Jiménez (2008) provide a solid basis for the second part in which topological interplay effects of oscillatory plasma discharges and channel flow will be investigated. Keywords: channel; figure; flow; plane; plasma; spanwise; velocity; wall
• Time-resolved flow field investigation in an industrial centrifugal compressor application involving TR-PIV synchronized with unsteady pressure measurements by Klinner, Joachim; Voges, Melanie; Schroll, Michael; Bassetti, Alessandro; Willert, Christian (2021) - Besides the challenging task to provide safer operation of the machine near surge in such experiments, advanced PIV methods in combination with unsteady pressure measurements can pro- vide important insights into the formation of stall cells and the interactions between pressure and velocity fluctuations as well as the propagation of aeroacoustic modes in the machine (cf. [ms] 0.8 0.6 0.4 0.2 0.0 0.2 0.4 0.6 0.8 C or r. co ef f. R Run 53 U - K2.1 U - K7 (a) 20 15 10 5 0 5 10 15 20 Lag [ms] 0.8 0.6 0.4 0.2 0.0 0.2 0.4 0.6 0.8 C or r. co ef f. R Run 100 U - K2.1 Uflt - K2.1 U - K7 Uflt - K7 (b) Figure 9: Cross-correlations of velocities of the inlet flow at location #1 (a) and the impeller exit flow at location #2 (b) at 100% speed ‘RI’ correlated with unsteady pressure signals on impeller casing entry at x/sm = 5% (K21) and immediately downstream of the rotor at x/sm = 110% (K7). Keywords: conditions; data; fig; flow; impeller; inlet; location; measurements; piv; pressure; speed; time; velocity
• First challenge on Lagrangian Particle Tracking and Data Assimilation: datasets description and planned evolution to an open online benchmark by Leclaire, Benjamin; Mary, Ivan; Liauzun, Cédric; Péron, Stéphanie; Sciacchitano, Andrea; Schröder, Andreas; Cornic, Philippe; Champagnat, Frédéric (2021) - Free-stream Reynolds number per unit length was set to ���,� = 665,000, leading to a boundary layer momentum thickness Reynolds number of ��� = 4,150 ten diameters upstream of the cylinder. The computational domain size is of 1.8 � × 0.1 � × 1.0 � in the streamwise (�), spanwise (�) and wall- normal (�) directions, with mesh cell number of 1367 × 500 × 247 = 168,824,500 cells. Keywords: challenge; flow; velocity; � �
• Enhanced data assimilation of 4D LPT with physics informed neural networks by Han, Jeongmin; Kim, Dong; Shin, Hyungmin; Kim, Kyung Chun (2021) - So, they have great potential for data assimilation to increase the spatial resolution. Figure 2(b) and 2(c) show the clear vortex structures than obtained by raw data and show the connected horseshoe vortex. Keywords: anfis; data; pinn; velocity
• Plunging jets from orifices of different geometry by Moscato, Giorgio; Romano, Giovanni Paolo (2021) - Water plunging jets develops in air, downstream sharp-edged orifice plates of two different shapes i.e. circular and rectangular. The facility for generation and investigation of plunging jets (on the left) and an example of plunging jet issuing from the rectangular orifice (on the right at the top). Keywords: jet; plunging; velocity
• Enhanced functional binning for one- and two-point statistics using a posteriori Uncertainty Quantification of LPT data by Godbersen, Philipp; Schröder, Andreas (2021) - The use and estimation of particle individual error values is similarly a topic were initial successes were presented but additional work is needed to fully utilize these concepts. The midpoint approach was suggested there directly because of an uncertainty propagation of particle position error trough the tracking scheme and velocity calculation, showing the midpoint to be the location of lowest velocity error. Keywords: approach; binning; data; error; measurement; particle; point; position; statistics; stb; time; track; uncertainty; velocity
• Time Resolved PIV of the Flow Field Underneath an Accelerating Meniscus by Ratz, Manuel; Fiorini, Domenico; Simonini, Alessia; Cierpka, Christian; Mendez, Miguel A. (2021) - The practical implications are numerous, especially considering that flow field and contact angle are intimately linked (see Savelski et al. (1995)). An adaptation of the tool for computing pressure field is currently in preparation (Sperotto et al., 2021). Keywords: cases; contact; field; figure; flow; interface; line; piv; test; velocity
• Adjustable window for 2D PIV estimation based on local Lagrangian coherency by Rahimi Khojasteh, Ali; Heitz, Dominique; Yang, Yin (2021) - We found that coherent optical flow has better velocity estimation in complex local regions. We compared the cross-correlation results with coherent optical flow, knowing that the synthetic analysis showed significant misestimation in such regions (see Figure 5.a). Keywords: estimation; figure; flow; interrogation; piv; velocity; vortex; window
• PIV measurement of buffer and logarithmic layers with detached eddies which mimics the neutral atmospheric surface layer by Hattori, Yasuo; Suto, Hitoshi; Nakao, Keisuke; Hirakuchi, Hiromaru (2021) - In the present study, we especially examine a PIV measurement with a long-distance microscope lens to discuss the interaction of turbulences structures between buffer and logarithmic layers, which must give a clue on Reynolds number effects Experimental apparatus and procedure We used the same experimental technique of our previous study (Hattori et al. 2010), except velocity measurements. PIV measurement of buffer and logarithmic layers with detached eddies which mimics the neutral atmospheric surface layer Y. Hattori1*, Hitoshi Suto1, Keisuke Nakao1, Hiromaru Hirakuchi1 1 Central Research Institute of Electric Power Industry, Civil Eng Lab, Abiko, Japan yhattori@criepi.denken.or.jp Motivation Accurate comprehension of turbulence characteristics in the atmospheric surface layer (ASL) under near neutral conditions, which is a lower part of the atmospheric boundary layer and a very high-Re number flow, is critically required in view of the increasing and broadening use of numerical weather prediction models. Keywords: layer; surface; turbulence; velocity
• LaPIV using multigrid warping and proxy regularization by Yang, Yin; Heitz, Dominique (2021) - If Eulerian flow is required, LAPIV is the preferred approach due to its simplicity and ability to utilize the original rich image features. Yang1∗, Dominique Heitz1 1 INRAE, UR OPAALE, F-35044 Rennes Cedex, France ∗ correspondent author: yin.yang@inrae.fr Abstract The Lagrangian Particle Image Velocimetry (LAPIV) method was firstly proposed in Yang et al. (2019) as a prototype approach to achieve the goal of accurate and efficient reconstruction of 3D Eulerian velocity field of fluid flow from multi-view particle images. Keywords: flow; grid; particle; velocity
• Towards the closure of Collar’s triangle by optical diagnostics by Gonzalez Saiz, Gabriel; Sciacchitano, Andrea; Scarano, Fulvio (2021) - Such force is less straightforward to obtain from fluid flow measurements as it typically requires high-quality time-resolved 3D measurements (Beresh, 2021). Bulletin of the American Physical Society 63 Jux C, Sciacchitano A, Scarano F (2020) Flow pressure evaluation on generic surfaces by robotic volumetric PTV. Keywords: aerodynamic; et al; flow; fluid; foil; forces; markers; measurement; motion; pressure; surface; velocity
• Validation of model-based correction for non-Stokesian tracers by Galler, Joshua Noah; Rival, David Emory (2021) - (b) Modelled sensor correction against PIV flow velocity measurements. In the present study, the tracer-velocity correction is evaluated by quantifying the residual error in measured flow velocity after the method of Galler et al. (2021) is applied. Keywords: flow; model; sensor; velocity
• Pressure from data-driven-estimated velocity fields using snapshot PIV and fast probes by Raiola, Marco; Chen, Junwei; Discetti, Stefano (2021) - The results of the ψ-filtered EPOD shows, at least for the present dataset, the lowest levels of error both in term of velocity field estimation (Fig. 4g) and of its time derivative (Fig. 4h), which lead to very low errors in the pressure estimation (Fig. 4i). 1 Introduction The availability of three-dimensional three-components (3D-3C) velocity fields, with time-resolution (thus 4D-3C) has open the path in the last decade to the measurements of pressure fields (Van Oudheusden, 2013; Van Gent et al., 2017). Keywords: epod; error; estimation; field; fig; flow; pressure; time; velocity
• Eulerian time-marching in Vortex-In-Cell (VIC) method: reconstruction of multiple time-steps from a single vorticity volume and time-resolved boundary condition by Jeon, Young Jin (2021) - Journal of Computational Physics 242, 480–497 Jeon YJ, Schneiders JFG, Müller M, Michaelis D and Wieneke B (2018) 4D flow field reconstruction from particle tracks by VIC+ with additional constraints and multigrid approximation. Since the majority of computation time is spent solving Poisson equations, the following estimate can be made: (Computation time)4D VIC# (Computation time)3D VIC# ≅ 𝐿 Keywords: approach; instances; method; particle; time; velocity; vic; ∆𝑇 𝑀
• GANs-based PIV resolution enhancement without the need of high-resolution input by Güemes, Alejandro; Sanmiguel Vila, Carlos; Discetti, Stefano (2021) - The challenge of achieving higher resolution flow fields is critical in turbulent flows in which the spatial scales have a wide spectrum, being the ratio between the integral scale and the Kolmogorov scale propor- tional to Re−3/4 (Pope, 2000), where Re is the Reynolds number based on the large-scale size and velocity. Indeed, while PIV fields are obtained from cross-correlation of groups of particle images, PTV provides vectors at the level of the single particle, without filtering effects. Keywords: case; fields; piv; resolution; velocity
• Super-resolution PIV using multi-frame displacement information by Yang, Hua; Ouyang, Zhenxing; Cao, Yunkang; Yang, Zhen; Yin, Zhouping (2021) - Multi-frame particle images collected by the developed system are used as the input low-resolution images for the following novel SR reconstruction algorithm. Multi-frame particle images collected by the developed system are used as the input LR images for the following novel SR reconstruction algorithm. Keywords: data; field; flow; frame; image; method; particle; reconstruction; resolution; velocity
• Application of simultaneous time-resolved 3-D PTV and Two Colour LIF in Studying Rayleigh-Benard Convection by Kashanj, Sina; Nobes, David (2021) - Therefore, to capture the Kr signal with maximum temperature sensitivity and to avoid receiving the Fl emitted signal, a bandpass filter (Edmund Optics) with CWL of 607 nm and FWHM of 36 nm is used, shown in light orange in Figure 4. It is also shown that for low temperatures, 𝑇 < 20 ℃ the temperature sensitivity decreases significantly Behshad et al.(2010). Keywords: figure; flow; laser; particle; ptv; temperature; velocity
• A representative driven system to interrogate passive dynamics of an airfoil in the wake of a cylinder by Hooper, Morgan Louise; McKeon, Beverley Jane (2021) - Discussed axes of airfoil motion labelled at left. effect appears to be caused by longer periods of inactivity in some of the passive cases, caused by the action of friction opposing the startup of airfoil motion (evidenced by extended periods where ẏ = 0, especially for PA11 and PA12). Keywords: airfoil; cases; cylinder; dynamics; figure; flow; motion; phase; power; thrust; velocity; vortex
• Determination of the Near Wall Flow of a Multi-Stage Tesla Diode Using PIV and PTV by Saffar, Yeganeh; Ansari, Shadi; Azadi, Reza; Raffel, Jan; Nobes, David; Sabbagh, Reza (2021) - The velocity field with uniform flow velocity for Re = 100 is shown in Figure 10 for forward and reverse flows. (a) (b) (c) (d) Figure 3: Image processing steps to obtain the wall boundaries of the geometry; (a) raw image showing the initial domain, (b) standard deviation of the intensities calculated from 1000 raw images, (c) the masked generated by image processing of the standard deviation of 1000 images, (d) result of masked image with seeding particles 4 Tessellation Combined with PTV Preliminary results obtained from PIV and PTV are compared to highlight the difference in the determined near wall flow. Keywords: figure; flow; image; ptv; tesla; tessellation; velocity
• Investigation of Large Scale Motions in Zero and Adverse Pressure Gradient Turbulent Boundary Layers Using High-Spatial-Resolution PIV by Jovic, Daniel; Shehzad, Muhammad; Sun, Bihai; Cuvier, Christophe; Willert, Christian; Ostovan, Yasar; Foucaut, Jean-Marc; Atkinson, Callum; Soria, Julio (2021) - 3 Results and Discussion Figure 2: Mean streamwise velocity profile (U+) with high momentum LSMs (U+ h ) and low momentum LSMs (U+ l ). Journal of Fluid Mechanics 448:53–80 Shehzad M, Sun B, Jovic D, Ostovan Y, Cuvier C, Foucaut JM, Willert C, Atkinson C, and Soria J (2021) Investigation of large scale motions in zero and adverse pressure gradient turbulent boundary layers using high-spatial-resolution particle image velocimetry. Keywords: lille; lsms; momentum; results; velocity
• An experimental approach to analyze aerosol and splatter formation in a dental practice by Mirbod, Parisa ; Haffner, Eileen A.; Bagheri, Maryam ; Higham, Jonathan E. (2021) - This plan is to perform experiments on the measurement of droplet sizes in the splatter created from a patient’s mouth by a Cavitron Ultrasonic Scaler (CUS) using optical flow tracking velocimetry (OFTV) and Shadowgraphy techniques. 3(a,b), shows measured droplet sizes ranges from 5 µm to 500 µm with a maximum observed speed of 1.4 m/s. Keywords: cus; dental; droplet; flow; size; velocity
• Lagrangian Strain- and Rotation-Rate Tensor Evaluation Based on Multi-pulse Particle Tracking Velocimetry (MPTV) and Radial Basis Functions(RBFs) by Li, Lanyu ; Sellappan, Prabu ; Schmid, Peter ; Hickey, Jean-Pierre; Cattafesta, Louis ; Pan, Zhao (2021) - As another example, Takehara and Etoh (2009) reconstructed the 2D vorticity field directly from PTV data using a Moving Least Square (MLS) method. In addition to contamination due to measurement noise, PTV data may not be well distributed. Keywords: data; error; fig; method; noise; particle; ptv; rate; rbf; velocity
• Velocity measurements of dilute suspensions over and through various porous media models by Haffner, Eileen ; Wilkie, Theresa ; Higham, Jonathan ; Mirbod, Parisa (2021) - Fluid motion over sediment beds Goharzadeh et al. (2005) and coral reefs/ submerged vegetation Ghisalberti and Nepf (2009) have been investigated as natural forms of porous media. These studies are limited to pure Newtonian fluid over and through porous media. Keywords: flow; media; slip; velocity
• Physics-based universal outlier detector for flow statistics by Saredi, Edoardo; Sciacchitano, Andrea; Scarano, Fulvio (2021) - Experiments in fluids 56:198 Duncan J, Dabiri D, Hove J, Gharib M (2010) Universal outlier detection for particle image velocimetry (PIV) and particle tracking velocimetry (PTV) data. Universal outlier detection for PIV data. Keywords: approach; detection; figure; flow; order; outliers; particle; transport; velocity
• Peregrine falcon wakes examined using Volumetric PIV by Talboys, Edward; Jagadeesh, Chetan ; Hyde, Martin ; Troolin, Daniel (2021) - Vortices enable the complex aerobatics of peregrine falcons. In the present work we have studied the complex fluid dynamics of the flow around the wing of a peregrine falcon in a stoop manoeuvre using the VPIV technique. Keywords: falcon; image; model; particle; velocity
• Main results of the first Lagrangian Particle Tracking Challenge by Sciacchitano, Andrea; Leclaire, Benjamin; Schroeder, Andreas (2021) - The participants received the calibration images and sets of particle images acquired by four virtual cameras, and were asked to produce as output the particles positions, velocities and accelerations (when possible) at a specific time instant. Particle images were acquired with four synthetic cameras at different seeding concentrations corresponding to a range of particles per pixel between 0.005 and 0.20. Keywords: acceleration; algorithm; case; et al; image; particles; ppp; time; velocity; � �
• Main results of the first Data Assimilation Challenge by Sciacchitano, Andrea; Leclaire, Benjamin; Schroeder, Andreas (2021) - The 13 output quantities were: - The three components of the velocity vector (� , ��, ��), in m/s; - The nine components of the velocity gradient tensor ( �� ��⁄ , �� ��⁄ , �� ��⁄ , ��� ��⁄ , ��� ��⁄ , ��� ��⁄ , ��� ��⁄ , ��� ��⁄ , ��� ��⁄ ) in s–1; - The static pressure p in Pa, relative to the point (�, �, �) = (0, 0.2, 0.01) From noisy particle tracks to velocity, acceleration and pressure fields using B-splines and penalties. Keywords: algorithms; errors; field; figure; flow; interpolation; particle; ppp; pressure; velocity; � �
• Investigation on computed pressures from PIV, a study of how boundary definitions affect pressure accuracy along objects on the example of a cylinder flow. by Felis-Carrasco, Francisco; Hess, David; Watz, Bo Beltoft; Mendez, Miguel Alfonso (2021) - 14th International Symposium on Particle Image Velocimetry – ISPIV 2021 August 1–5, 2021 A study on PIV-based pressure measurements using CFD techniques F. Felis-Carrasco1, B. B. Watz1, D. Hess1∗, M. A. Mendez2 1 Dantec Dynamics A/S/Company, Copenhagen, Denmark 2 von Karman Institute for Fluid Dynamics, Sint-Genesius-Rode, Belgium ∗ dhs@dantecdynamics.com Abstract This work discusses an approach to compute pressure fields from planar PIV measurement using standard CFD tools. Standard techniques from CFD (Computational Fluid Dynamics) offers powerful and efficient tools to compute pressure fields from velocity fields (Gunaydinoglu and Kurtulus, 2020; Regert et al., 2011). Keywords: cylinder; field; figure; flow; grid; mesh; piv; pressure; solver; velocity
• Aerodynamics of a cycling wheel in crosswind by coaxial volumetric velocimetry by Jux, Constantin; Sciacchitano, Andrea; Scarano, Fulvio (2021) - Authors developing numerical tools for the aerodynamic analysis of cycling wheels, however, have to rely on the experimentally documented force data for validation of their simulations. Journal of Wind Engineering and Industrial Aerodynamics 82:209–222 Zdravkovich M (1992) Aerodynamics of bicycle wheel and frame. Keywords: angle; data; force; rim; tire; velocity; wheel; wind; yaw
• Tracer-based 3D surface reconstruction by Jux, Constantin; Scarano, Fulvio; Sciacchitano, Andrea (2021) - Authors developing numerical tools for the aerodynamic analysis of cycling wheels, however, have to rely on the experimentally documented force data for validation of their simulations. Journal of Wind Engineering and Industrial Aerodynamics 82:209–222 Zdravkovich M (1992) Aerodynamics of bicycle wheel and frame. Keywords: angle; data; force; rim; tire; velocity; wheel; wind; yaw
• Three-dimensional temperature and velocity measurements in fluids using thermographic phosphor tracer particles by Stelter, Moritz; Martins, Fabio J. W. A.; Beyrau, Frank; Fond, Benoît (2021) - As described in the next paragraph, each sextet of particle images is used for extraction of particle position, velocity and temperature information. Particle velocity is assessed based on the displacement of paired particles between both reconstructed fields. Keywords: particle; temperature; velocity
• Spatially and temporally resolved measurements of turbulent Rayleigh-Bénard convection by Lagrangian particle tracking of long-lived helium-filled soap bubbles by Bosbach, Johannes; Schanz, Daniel; Godbersen, Phillip; Schröder, Andreas (2021) - 6 Conclusions We have demonstrated that by combination of STB / LPT with long-lived HFSB simultaneous acquisition of Lagrangian particle tracks and time-resolved Eulerian velocity fields of turbulent RBC spanning the com- plete volume of a cylindrical sample becomes possible. Large scale particle image velocimetry with helium filled soap bubbles. Keywords: convection; data; et al; figure; flow; hfsb; lsc; particle; time; tracks; turbulent; velocity
• Particle pair statistics of inertial particles at small separation using stereoscopic particle tracking by Hoffman, Davis W.; Eaton, John K. (2021) - Dou et al. (2018) extracted particle velocities with greater fidelity using 4-frame stereo particle tracking velocimetry (PTV). (3) In Eq. 3, Pi(r) is the number of particle pairs separated from the ith particle by a distance r and r+dr, δVi(r) is the shell volume in n-dimensions between radii r and r+ dr, Np is the total number of particles, and V is the total measurement volume. Keywords: distribution; frame; number; particle; ptv; relative; stereo; velocity
• Dense flow field interpolations from PTV data in the presence of generic solid boundaries by Cakir, Bora Orcun; Sciacchitano, Andrea; Gonzalez Saiz, Gabriel; van Oudheusden, Bas (2021) - (Gesemann et al., 2016) introduced the use of 3D cubic B- splines for increasing signal-to-noise ratio of particle information reconstruction over particle velocity and accelerations. The resultant velocity fields is used as an input into VIC+ iterative procedure while velocity fields are corrected with immersed boundary treatment (blue boxes) to find the optimization variables that yield velocity and material derivative distributions of minimum discrepancy with the PTV measurements (orange box). Keywords: ale; boundary; data; field; flow; fluid; grid; imvic+; information; interpolation; mesh; method; particle; pressure; ptv; reconstruction; surface; velocity; vic+
• Error propagation dynamics of PIV-based pressure field calculation (3): What is the minimum resolvable pressure in a reconstructed field? by Pan, Zhao; Whitehead, Jarad P.; Rechards, Geordie; Smith, Barton L. (2021) - The accuracy of pressure fields derived from PIV data has improved with the PIV technique itself, as hardware improvements provide increased spatial and temporal resolution and new techniques have provided a fully three-dimensional velocity field (Scarano, 2012). Examples in classic topics include pressure field and loads on airfoils (Jeon et al., 2016; Lignarolo et al., 2014), water slamming pressure of boat hull (Porfiri and Shams, 2017), as well as pressure distribution in turbulent boundary layers (Ghaemi et al., 2012; Zhang et al., 2017). Keywords: error; experiments; field; flow; numerical; piv; pressure; pressure field; resolution; setup; velocity
• Time-resolved sphere and fluid motions in turbulent boundary layers by Tee, Yi Hui; Longmire, Ellen K. (2021) - Sphere spanwise motion The spanwise trajectories of spheres P1 and P3 at Reτ 14th International Symposium on Particle Image Velocimetry – ISPIV 2021 August 1–5, 2021 Time-resolved sphere and fluid motions in turbulent boundary layers Yi Hui Tee1∗, Ellen K. Longmire1 1 University of Minnesota, Aerospace Engineering and Mechanics, Minneapolis, USA ∗ teexx010@umn.edu Abstract This paper extends the study by Tee et al. (2020) to investigate the effect of large coherent structures on motion of spheres with specific gravities of 1.006 (P1) and 1.152 (P3) at Reτ Keywords: fluid; lift; mean; motion; particle; reτ; sphere; streamwise; velocity; wall
• An Experimental Study to Quantify the Rotor-to-Rotor Interaction Characteristics of a Small Unmanned-Aerial-Vehicle by Zhou, Wenwu; Ning, Zhe; Hu, Hui (2021) - Phase-locked vorticity distributions for the single rotor (left) and twin rotors (right, L=0.05D) configurations: Stereoscopic PIV results for the single rotor (left) and twin rotors (right, L=0.05D) configurations at X/D = 0.1, 0.5, and 1.0 locations. Keywords: fig; flow; interactions; noise; piv; plane; results; rotor; rotor case; separation; thrust; tke; uavs; velocity
• Effect of the boundary conditions, temporal, and spatial resolution on the pressure from PIV for an oscillating flow by Sakib, Nazmus; Mychkovsky, Alexander; Wiswall, James; Samaroo, Randy; Smith, Barton (2021) - On the quasi-instantaneous aerodynamic load and pressure field measure- ments on turbines by non-intrusive PIV. Pressure field reconstruction from the velocity field obtained by cutting edge particle tracking meth- ods, such as Shake the Box, (STB) (Schanz et al., 2016) and the study of the relevant parameters on the pressure field will be included in future studies. Keywords: boundary; conditions; field; flow; piv; pressure; pressure field; resolution; time; velocity
• Stereoscopic Micro PIV Investigation of Velocity Boundary Layer Near Piston Top of a Tumble Enhanced SI IC Engine by Shimura, Masayasu; Yokoyama, Eiji; Kosuda, Hiroki; Kamata, Makoto; Nakabeppu, Osamu; Yokomori, Takeshi; Tanahashi, Mamoru (2021) - In our previous study (Shimura et al., 2018), a micro PIV was conducted in a motored engine cylinder to investigate velocity boundary layer characteristics near piston top before the top dead center (TDC) at a constant engine speed of 2000 rpm to deepen understanding characteristics of velocity boundary layer in engine cylinder with tumble flow. In the previous study (Jainski et al., 2013), a micro particle image velocimetry (micro PIV) measurements were conducted in an engine cylinder at up to 1100 rpm and the characteristics of velocity boundary layer around a cylinder head were investigated. Keywords: engine; layer; micro; tumble; velocity
• Utilization of direct forcing immersed boundary methods for the optimization of inertial focusing microfluidics by Giolando, Patrick; Ma, Hui; Kinzer-Ursem, Tamara; Wereley, Steve (2021) - The expanded well design produced two separate fluid domains with dramatically different Reynolds numbers (Re), which required separate in-house algorithms for the quantification of particle velocities. (D) Final quantification of particle velocities in the entire system. Keywords: data; flow; fluid; forcing; model; particle; velocity
• Volumetric Flow Rate Measurement using Surface Imaging Techniques by Chavez Dorado, Julio Enrique; Johnson, , Blair Anne (2021) - and L22,1 were used with measured flow depth to build a linear relationship and obtain local flow depths across the FOV. 3 Results & discussion Test L11,1 Surface flow and boundary layer data were collected via SPIV and acoustic Doppler velocimetry (ADV), respectively. Keywords: channel; flow; surface; velocity
• Large Scale Infrared-Based Remote Sensing of Turbulence Metrics in Surface Waters: Going Beyond Mean Flow by Schweitzer, Seth Avram; Cowen, Edwin Alfred (2021) - These spatial differ- ences in temperature form a rich texture of patterns on the water surface that are ob- servable in IR images (figure 2). IR images are a record of radiation emitted by the wa- ter surface, with no external illumination, and no concerns of possible differences be- tween motion of tracer particles and the flow. Keywords: image; surface; velocity; water
• Evaluation of velocity fields in horizontal gas-liquid intermittent flows using Stereoscopic-PIV and instantaneous masking procedure by Fernandes, Leonardo Soares; de Mesquita, Rodrigo dos Santos Navarro; Martins, Fabio Jessen Werneck de Almeida; Azevedo, Luis Fernando Alzuguir (2021) - In fact, an analysis of classical gas-liquid flow pattern maps (Baker, 1953; Brennen, 2005) clearly shows that the intermittent flow regime (elongated bubble flow and slug flow) occupies a large area in the maps, i.e., it is the dominant flow pattern for a considerable combination of gas and liquid flow rates, justifying the study of this gas-liquid flow pattern. The averaged mask described above was used to separate gas regions, where seeding particles Table 2: Comparison of expected and measured mixture velocity for each case. Keywords: bubble; bubble nose; figure; flow; gas; gas bubble; liquid; nose; pipe; velocity
• Large Scale PIV for confined fires by Varea, Emilien; Betting, Benjamin; Gobin, Carole; Godard, Gilles; Patte-Rouland, Béatrice ; Lecordier, Bertrand (2021) - Second, the transition from ventilated to under ventilated fire conditions is evaluated 2. * Correspondent author: bertrand.lecordier@coria.fr Keywords: Large scale PIV, PIV processing, Fire, Enclosure fire. Keywords: air; dynamics; fire; piv; velocity
• Highly accurate optical flow method based on volumetric segmentation for 3D PIV by Yang, Hua; Shi, Hang; Lu, Jin; Kang, Menggang; Yin, Zhouping (2021) - It can be seen from the synthetic data that compared with the 3D cross-correlation method and 3D global optical flow method, the proposed VS-OF method can obtain velocity fields with greater accuracy. The proposed VS-OF method has excellent comprehensive performance in terms of flow velocity estimation due to the process of velocity field segmentation. Keywords: field; flow; method; particle; velocity; volume
• Design of experiments: a statistical tool for PIV uncertainty quantification by Adatrao, Sagar; Sciacchitano, Andrea; Velden, Simone van der; Meulen, Mark-Jan van der; Cruellas Bordes, Marc (2021) - 1 Introduction Despite the quantification of PIV uncertainty being the key to discern measurement errors from the true flow physics, PIV uncertainty quantification (UQ) is often hindered by the complexity of the measurement chain, which introduces errors from various sources such as particles, illumination, imaging and processing. The methodology is assessed for an experimental test case of the flow at the outlet of a ducted Boundary Layer Ingesting (BLI) propulsor to quantify the total uncertainty in time-averaged velocity from stereoscopic PIV measurements as well as the constituent systematic uncertainties due to the experimental factors, namely, camera aperture, inter-frame time separation, interrogation window size and stereoscopic camera angle. Keywords: factors; flow; fluctuations; image; particle; total; uncertainty; velocity
• Investigation of turbulent boundary layer flows with adverse pressure gradient by means of 3D Lagrangian particle tracking with Shake-The-Box by Novara, Matteo; Schanz, Daniel; Geisler, Reinhard; Agocs, Janos; Eich, Felix; Bross, Matthew; Kähler, Christian; Schröder, Andreas (2021) - Interaction of coherent flow structures in adverse pressure gradient turbulent boundary layers. Journal of Fluid Mechanics 873:287–321 Chen J (2019) Two-point statistics of coherent structure in turbulent flow. arXiv preprint arXiv:190805422 Cierpka C, Lütke B, and Kähler CJ (2013) Keywords: apg; direction; figure; flow; particle; region; structures; velocity; wall; zpg
• A Grid-free least-squares method for pressure evaluation from LPT data by Bobrov, Maxim; Hrebtov, Mikhail; Ivashchenko, Vladislav; Mullyadzhanov, Rustam; Seredkin, Alexander; Tokarev, Mikhail; Zaripov, Dinar; Dulin, Vladimir; Markovich, Dmitriy (2021) - Figure 1: Location of the virtual cameras with respect to the coordinate system and a flow domain where particles were initially seeded (larger box) and ROI (smaller box) with visualization of the vortex structures with instantaneous isosurface of λ2 =−5 colored by streamwise velocity magnitude In order to study the effect of particle image concentration (up to 0.2 ppp) on the overall accuracy, two hundred thousand inertial particles were randomly and uniformly seeded into a flow domain as illustrated in Figure 1. The examples of the results are presented in Figures 2 and 3. Particle image concentration Nppp = 0.05 is shown in Figure 2 for the comparison with the Hacker’s data. Keywords: method; pressure; velocity
• Time-resolved Velocity Estimation from Inflow Pressure Measurements in a Subsonic Jet Using Machine-Learning Methods by Li, Songqi; Li, Wenyan; Ukeiley, Lawrence (2021) - (a) Experimental setup of inflow pressure measure- ments synchronized with PIV (b) Overview of velocity estimation from pressure inputs Figure 1: Time-resolved velocity estimation from inflow pressure synchronized measured with PIV. In this work a ML estimation approach was applied to estimate TR velocity from the experimental dataset (see Figure 1(b)). Keywords: estimation; time; velocity
• Multi-resolution, time-resolved PIV measurements of a Decelerating Turbulent Boundary Layer near Separation by Willert, Christian E; Novara, Matteo; Schanz, Daniel; Geisler, Reinhard; Schroll, Michael; Ribergard, Simon; Schroeder, Andreas (2021) - Near the point of flow separation high-resolution imaging at high camera frame rates captured the time evolving velocity profile using the so-called “profile-PIV” technique in a nested imaging configuration of two cameras operating at different image magnifications. U = 35.0 [STB] d) 0.001 0.01 0.1 1 y / 99 0.005 0.000 0.005 0.010 0.015 0.020 u i u j /U 2 e u u v v u v 0.1 mm 1 mm 10 mm 100 mm Figure 6: Mean streamwise velocity profiles (a,b) and variances and covariance of the streamwise and wall-normal velocity components (c,d), for ZPG condition (a,c) und APG (b,d). Keywords: apg; boundary; camera; data; flow; layer; piv; time; velocity; wall
• 3D pressure field reconstruction from time-resolved stereoscopic PIV measurements by relaxation of Taylor's hypothesis by Fratantonio, Dominique; Charonko, John James (2021) - Experiments in fluids 57:1–22 Van Gent P, Michaelis D, Van Oudheusden B, Weiss PÉ, de Kat R, Laskari A, Jeon YJ, David L, Schanz D, Huhn F et al. (2017) Comparative assessment of pressure field reconstructions from particle image velocimetry measurements and lagrangian particle tracking. × 𝝎 Planes re-initialization Velocity reconstruction Pressure reconstruction Figure 1: Schematic of the algorithm for 3D pressure reconstruction starting from SPIV velocity measure- ments. Keywords: field; flow; method; pressure; pressure reconstruction; reconstruction; spiv; time; velocity

• Simultaneous Particle Tracking and Temperature Measurements during Additive Manufacturing using a High-speed Spectral Plenoptic Camera by Kelly, Dustin; Fischer, Ralf; Goldman, Ari; Morris, Sarah; Prorok, Bart; Thurow, Brian (2021) - The majority of particle temperatures ranged between 1000◦C to 1600◦C. With a melting temperature of approximately 1300◦C, the Inconel 625 particles were present in both liquid and solid states. Ray bundling takes advantage of the two plane param- eterization, where perspective images are first generated and particle locations are found through applying a minimum threshold. Keywords: camera; microlens; particle; spectral; temperature
• Detecting vortical structures in time-resolved volumetric flow fields by Agarwal, Karuna; Ram, Omri; Wang, Jin; Lu, Yuhui; Katz, Joseph (2021) - Streamwise vortex structure in plane mixing layers. Lagrangian coherent structures and the smallest finite-time Lyapunov exponent. Keywords: particle; pressure; qsvs; structures; time
• Calibration correction of arbitrary optical distortions by non-parametric 3D disparity field for planar and volumetric PIV/LPT by Michaelis, Dirk ; Mychkovsky, Alexander; Wiswall, James; Prevost, Richard; Neal, Doug; Wieneke, Bernhard (2021) - Left: polynomial calibration model (systematic misalignment between markers and Cartesian grid of up to 22 pixel), right: polynomial model with correction field (all calibration marks are centered on the Cartesian grid). Cam 1 Cam 2 Cam 3 Cam 4 14th International Symposium on Particle Image Velocimetry – ISPIV 2021 August 1–5, 2021 Figure 6: Scatter plot of the two components, Vx and Vy, of disparity vectors from the 1st (left) and the 8th (right) iteration of volume self-calibration without correction field applied (camera , Vx and Vy in pixels) Keywords: calibration; correction; distortions; field; fig; flow; image; particle; volume
• Unsupervised Recurrent All-Pairs Field Transforms for Particle Image Velocimetry by Lagemann, Christian; Klaas, Michael; Schröder, Wolfgang (2021) - In this light, PIV images pose an even greater chal- lenge on unsuspervised optical flow networks since they contain many, but tiny and almost identical image features - the particles - and hence, provide similar image patterns within the local neighborhood impeding the prediction of the physical correct displacement. Therefore, we propose URAFT-PIV, an unsupervised deep neural network architecture for optical flow estimation in PIV applications and show that our combination of state-of-the-art deep learning pipelines and unsupervised learning achieves a new state-of-the-art accuracy for unsupervised PIV networks while performing similar to supervisedly trained LiteFlowNet based competitors. Keywords: correlation; displacement; flow; image; learning; loss; network; particle; piv; uraft
• Uncertainty propagation and truncation errors in LPT kinematics by Chatellier, Ludovic (2021) - For TP measurements, the two-point centered derivation scheme leads to 3rd order truncation errors for the first derivative, although it is based on a first order development. For higher order schemes on MP measurement leading to long tracks, the orders of derivation needed to estimate the truncation error are accessible by simply increasing the order of the scheme of interest by a few units. Keywords: error; order; particle; truncation
• Three-Dimensional Particle Tracking Velocimetry using a Single Time-of-Flight Camera by Morris, Sarah; Goldman, Ari; Thurow, Brian (2021) - The use of range-imaging cameras such as LIDAR and ToF technology as a flow diagnostic tool has been increasing, for example LIDAR-based PIV has been shown to successfully analyze very large slow-moving solid objects like glaciers (Telling et al., 2017), and ToF cameras have been used in combination with traditional PIV for data enhancement of seeded flows (Augère et al., 2017). ToF cameras have also been used to evaluate planar seeded flow, with independent camera and light sources (Paciaroni et al., 2018). Keywords: camera; depth; experiments; field; figure; light; particle; ptv; time; tof
• Applications of Particle Tracking Velocimetry to severe nuclear accident experimentation by Johnson, Michael; Journeau, Christophe (2021) - A PTV algorithm is presented whereby candidate particle pairings are assessed in terms of a weighted similarity index enabling the re- jection of candidate particles of insufficient likeness to the paired sighting prior to particle matching. A bespoke PTV algorithm is presented whereby candidate particles are refined by user-defined similarity cri- teria prior to particle matching, enabling the distinction between the tolerable deformation of a molten fuel droplet and a more significant fragmentation event which constitutes the formation of new particles. Keywords: corium; et al; figure; frame; image; johnson; melt; particle; ptv; sightings; spreading
• Simultaneous two-phase flow measurements in a high-speed particle-laden under-expanded jet by Diaz-Lopez, Miguel Xavier; Rubio, Juan Sebastian; Ni, Rui (2021) - The sufficient large scale separation between inertial particles with size in the range of O(10)–O(100) µm and aerosol tracer particles makes it easy to segment their images from the PIV data. To study the dynamics of inertial particles, a particle injector and accelerator were employed to inject particles from a particle chamber into the gas stream along the centerline of the jet. Keywords: image; inertial; particle; piv; pulse
• A novel streak velocimetry technique based on 2D fits of decaying phosphor particle images by Fan, Luming; Vena, Patrizio; Savard, Bruno; Xuan, Guangtao; Fond, Benoît (2021) - In this study, a new velocimetry technique is proposed, based on phosphor particle streaks and 2D least-square fitting to the analytical expression of the emission trajectory. A novel streak velocimetry technique based on 2D fits of decaying phosphor particle images Luming Fan1,2,3, Patrizio Vena2, Bruno Savard3,4, Guangtao Xuan1, Benoît Fond1,* 1Otto-von-Guericke-Universität Magdeburg, Universitätsplatz 2, 39106, Germany 2National Research Council (NRC), 1200 Montreal Road, Ottawa ON K1A 0R6, Canada 3University of Ottawa, 75 Laurier Ave., Ottawa, ON K1N 6N5, Canada 4Polytechnique Montréal, 2500 Chemin de Polytechnique, Montréal, QC H3T 1J4, Canada Keywords: particle; phosphor; technique; velocimetry
• Particle Detection by means of Machine Learning in Defocusing PTV by Dreisbach, Maximilian; Leister, Robin; Probst, Matthias; Friederich, Pascal; Stroh, Alexander; Kriegseis, Jochen (2021) - In experiments on synthetic images and artificial particle images produced through a pinhole aperture RetinaNet achieves a higher accuracy than the Hough transformation. [px] In te ns ity [- ] Synthetic MUNIT Real (b) Radial intensity distribution - 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0 0.25 0.5 M is s ra te [- ] Faster R-CNN Hough RetinaNet - 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0 1 2 Overlap [IoU] σ D [p x] (c) Results on overlapping particles Figure 2: (a) Random synthetic (Da), real and translation refined particle images (Db) at ascending diam- eters; (b) averaged radial intensity profiles of synthetic (Da) and refined synthetic (Db) and real particle images with a diameter of D = 22.5±0.025px; (c) miss rate and uncertainty in diameter determination σD on synthetic particle images with increasing relative overlap, measured by intersection over union (IoU). Keywords: images; institute; particle; synthetic
• Lagrangian Particle Tracking: a link between localization error and fraction of missed particles by Cornic, Philippe; Champagnat, Frédéric; Leclaire, Benjamin (2021) - 4.3 Consistency with 1st LPT challenge results This RMSE on particle localisation error model is very simple. Section 4 presents the RMSE on particle localisation model depending for a given setup and seeding density on only (a) (b) Figure 1: (a): cameras setup. Keywords: bar; challenge; figure; localisation; lpt; model; particle; rmse
• A novel volumetric velocity measurement method for small seeding tracers in large volumes by Zhang, Yisheng; Abitan, Haim; Ribergård, Simon Lautrup; Velte, Clara M. (2021) - Velocity fidelity of flow tracer particles. Response time and Stokes number are related to the fidelity of tracer particles accurately following the flow. Keywords: camera; diameter; et al; experiments; flow; light; particle; scale; seeding; tracers
• Large-scale 3D flow investigations around a cyclically breathing thermal manikin in a 12 m³ room using HFSB and STB by Schröder, Andreas; Schanz, Daniel; Bosbach, Johannes; Novara, Matteo; Geisler, Reinhard; Agocs, Janos; Kohl, Andreas (2021) - After many seconds up to a minute the mixed air with a therefore massively lowered local concentration of exhaled aerosol particles reaches the side walls and starts to descend into the room while creating large low-speed and almost laminar recirculation rollers (see Fig. Based on the gained knowledge from recent worldwide research activities on airborne transmission of SARS-CoV-2 viruses between humans in closed rooms with and without wearing masks or other mitigation measures it is still of specific high interest to understand in detail the Lagrangian transport processes and pathways of small aerosol particles exhaled by a human source including their dispersion and accumulation characteristics. Keywords: aerosol; air; breathing; et al; flow; image; manikin; masks; particle; room; sars; time; transport
• Development of Echo-LPT for the study of particle-wall interactions in dense suspensions by Samie, Milad; Zhang, Kai; Najjari, Mohammad Reza; Rival, David E. (2021) - The obtained UIV results were used as benchmark tests to validate the accuracy of eLPT measurements. The resulting pathlines describe the lifespan of each fluid parcel within the measurement domain and can be used to extract path-dependent quantities, including particle approach velocity, incidence angle, particle-wall collision rate, particle residence time, and depletion efficiency. Keywords: elpt; particle; study; uiv
• Particle position prediction based on Lagrangian coherency for flow over a cylinder in 4D-PTV by Rahimi Khojasteh, Ali; Heitz, Dominique; Yang, Yin (2021) - By tracking each Figure 2: Schematic of particle trajectories in 2D pair vortices starting from t1 to t5: t1), The target particle with coherent neighbour particles located in a clockwise vortex (golden cluster), non-coherent particles belong to different clusters; t2), The target particle trajectory (golden line) approaching to particles in the red cluster; t3), The target particle separation with non-coherent particles in the red cluster and approaching to particles in the grey cluster; t4), Separation of non-coherent particles in the grey cluster with the target particle; t1−t5), Full trajectory view of the target particle alongside with coherent particles in golden cluster. On the other hand, the information of coherent particles should be shared with each neighbour particle to predict their behaviour accurately and avoid misprediction. Keywords: figure; function; particle; polynomial; positions; prediction; time
• Measurement of the acoustic streaming pattern in a standing surface acoustic wave field by Sachs, Sebastian; Cierpka, Christian; König, Jörg (2021) - Flow field in sectional planes lengthwise (c, x′ = 250 µm) and crosswise (d, y′ = 90.7 µm) to the microchannel at the beginning (dashed line) of the sSAW. 14th International Symposium on Particle Image Velocimetry – ISPIV 2021 August 1–5, 2021 Measurement of the acoustic streaming pattern in a standing surface acoustic wave field S. Sachs1∗, C. Cierpka1, J. König1 1 Technische Universität Ilmenau, Institute of Thermodynamics and Fluid Mechanics, Ilmenau, Germany ∗ sebastian.sachs@tu-ilmenau.de 1 Introduction The application of standing surface acoustic waves (sSAW) has enabled the development of many flexible and easily scalable concepts for the fractionation of particle solutions in the field of microfluidic lab-on- a-chip devices. Keywords: field; flow; particle; ssaw
• Ghost particle reduction in particle streak velocimetry by Tsalicoglou, Christina; Roesgen, Thomas (2021) - 2 Methods and Results Maas (1992) described the probability of generating ghost particles from images of randomly distributed particles as a function of the particles per pixel, volume depth, and relative position of the cameras. The resulting number of ghost streaks, compared to that of ghost particles, demonstrates the advantage of reconstructing line segments (streaks) instead of points (particles) and validates our probability analysis (Fig. 1(b)). 3 Conclusions With long-exposure particle imaging in 3D-PSV, particle pathlines are obtained, instead of frozen particle positions as in conventional 3D-PTV and Tomo-PIV. Keywords: ghost; particle; streaks
• Ultrasound PIV Uncertainty Quantification by Derakhshandeh, Rozhin; Bhattacharya, Sayantan; Meyers, Brett; Vlachos, Pavlos (2021) - Particle images are formed across several ultra- sound scan lines, yielding an elliptical particle image shape. The performance of the modified IM, MC, and CS methods are tested using synthetic ultrasound images (Meunier and Bertrand, 1995) that represent a range of error sources, including particle image diameter, noise, seeding density, displacement, and flow shear rate. Keywords: image; particle; uncertainty; upiv
• Effects of Particle Properties on Visualizing Flows in a Two- Stage Electrostatic Precipitator Using Particle Image Velocimetry by Darma, Gede Suantara; Tien, Wei-Hsin (2021) - The results show that by increasing charge voltage from 8 kV to 12 kV with a streamwise flow velocity the 2.36 m/s, the y-component velocity for Al2O3 particle, oil droplet particle, NaCl particle and TiO2 particle increased by 50.6%, 76.0%, 33.5% and 51.9%, respectively. Moreover, for the case of the 4.18 m/s primary flow, the y-component velocity for Al2O3 particle, oil droplet particle, NaCl particle and TiO2 particle increase by 52.7%, 59.2%, 59.4% and 65.9% after the voltages increase from 8 kV to 12 kV. PIV results for oil droplet particle shows slower y-component velocities, which can be due to the lower Archimedes number of 3.12E-06 and the mobility number that is larger than 3. Keywords: flow; particle
• Visualization of Three-Dimensional Acoustic Streaming Flow Patterns around an Inclined Triangular Obstruction using Digital In-Line Holographic Micro-Particle Tracking Velocimetry by Hung, Sheng Po; Tien, Wei-Hsin (2021) - Using Rayleigh- Sommerfeld back-propagation method[7], particle locations was reconstructed frame by frame and 3-D tracking of individual particles was performed afterwards. [4] P. Memmolo et al., Recent advances in holographic 3D particle tracking, Advances in Optics and Photonics, vol. 7, no. 4, pp. Keywords: particle; streaming; vol
• Shake-The-Box particle tracking with variable time-steps in flows with high velocity range (VT-STB) by Schanz, Daniel; Novara, Matteo; Schröder, Andreas (2021) - The one particle p that minimizes �������⃗ − ��2,/��������⃗ � < )�2 for a given track t is chosen for continuing t in the current time-step. If such a situation is limited to a single time-step ��, STB is typically stable enough to still predict a location at ���� that is accurate enough for the shaking process to converge to the true position. Keywords: image; iteration; particle; stb; steps; time; tracking; δ �; � ⃗; � �
• Measurement of kinetic constant of protein binding using microfluidics and particle diffusometry by Ma, Hui; Wereley, Steven; Linnes, Jacqueline; Kinzer-Ursem, Tamara (2021) - Processing the image sets of the protein-conjugated particles’ binding process, we acquire the relation of particle size and time, which can be used to solve protein binding kinetics. Particle size increases due to binding can be measured by PD. C. Experiment setup. Keywords: binding; particle; protein; size
• On the uncertainty of defocus methods for 3D particle tracking velocimetry by Cierpka, Christian; Sachs, Sebastian; Mäder, Patrick; Chen, Minqian; Barnkob, Rune; Rossi, Massimiliano (2021) - For this reason, synthetic images were used which show a systematic variation of the imaging conditions, in this case, the degree of astigmatism (none, mild, strong), the noise level and the number of particle images per pixel (Rossi, 2020). A high value of the correlation between template and particle image indicates the same depth position. Keywords: image; methods; particle; rossi
• Pressure calculation for flows with moving surface boundaries from particle tracking velocimetry (PTV) by Azadi, Reza; Nobes, David S. (2021) - This makes the current pressure calculation methods inapplicable to a flow domain with deformable moving surface boundaries. The conservation equations of volume, mass, and momentum, governing an isotropic fluid flow, embedded in a control volume (C.V.) with deformable surface boundaries are formulated as [6]: 𝑑𝑉 𝑑𝑡 = ∫ 𝐮S ∙ 𝐧𝑑𝐴𝑆(𝑡) , (1) 𝑑(𝜌𝑉) 𝑑𝑡 + ∫ 𝜌(𝐮 − 𝐮S) ∙ 𝐧𝑑𝐴𝑆(𝑡) Keywords: flow; particle; pressure; ptv; surface
• Measurement of Lagrangian Trajectories in a 3 L Stirred Tank Reactor using 4D Particle Tracking Velocimetry with Shake-the-Box by Fitschen, Jürgen; von Kameke, Alexandra; Hofmann, Sebastian; Hoffmann, Marko; Schlüter, Michael (2021) - In this work, for the first time, instantaneous flow field measurements with high spatial and temporal resolution are performed in the entire volume of a 3L stirred tank reactor based on 4D particle tracking velocimetry. 1 Experimental Method and First Results The fluid dynamics of a 3L stirred tank reactor are investigated (see Figure 1) using 4D particle track- ing. Keywords: flow; particle; reactor
• Approximate Bayesian framework for 3D reconstruction in a volumetric PIV/PTV measurement by Bhattacharya, Sayantan; Bilionis, Ilias; Vlachos, Pavlos (2021) - The latter compromises triangulation accuracy (Maas, Gruen and Papantoniou, 1993) due to overlapping particle images for higher particle concentrations. In equation (1), 𝐼0, 𝜎𝑑 are image parameters estimated from the optical transfer function (OTF) of particle images. Keywords: camera; image; particle; reconstruction
• TrackFit: Uncertainty Quantification, Optimal Filtering and Interpolation of Tracks for Time-Resolved Lagrangian Particle Tracking by Gesemann, Sebastian (2021) - Listing 1: GNU Octave example script for estimating the power spectral density based on autocorrelation coefficients via an auto-regressive model of order p. 2.3 Test and comparison of spectral estimation methods To test the various spectral estimation methods a ground truth spectrum has been chosen that is believed to be representative of typical particle tracks including measurement noise, see figure 1. Figure 1: Power spectral density estimation method comparison for a synthetically generated case. Keywords: estimation; filter; noise; particle; signal; spectral
• A Kalman filtering approach to particle track filtering and track uncertainty quantification for 3D PTV measurement by Sethu Viji, Rudra; Eshraghi, Javad; Zhang, Jiacheng; Brindise, Melissa C; Bhattacharya, Sayantan; Vlachos, Pavlos P (2021) - Xp (2) (a) Noise 0% (b) Noise 5% (c) Noise 10% Figure 1: Cumulative distribution of RMS error in track velocity estimates for a 3D synthetic vortex ring, generated at a seeding density of 0.025ppp. The investigation on the performance of the P-type KF applied to the 3D-PTV position and velocity measurements is twofold: one on the tracked particle positions and the other on particle velocity estimates. Keywords: particle; ptv; uncertainty

• PIV investigation of cavitating flows around circular cylinders with hydrophobic coatings by Dobroselsky, Konstantin; Lebedev, Anatoliy; Safonov, Alexey; Starinskiy, Sergey; Dulin, Vladimir (2021) - 14th International Symposium on Particle Image Velocimetry – ISPIV2021 August 1–5, 2021 1 PIV investigation of cavitating flows around circular cylinders with hydrophobic coatings K. Dobroselsky, A. Lebedev, A. Safonov, S. Starinskiy, V. Dulin* 1 Kutateladze Institute of Thermophysics, Novosibirsk, Russia *corresponding author: vmd@itp.nsc.ru The treatment of the hydrophobic properties of solid surfaces is considered as a passive method to reduce the drag in water flows (Rothstein, 2010) and to potentially affect the flow separation and vortex shedding (Sooraj et al., 2020). The scheme of nanosecond laser removal of fluoropolymer coating from stainless steel cylinder surface. Keywords: coating; flow; laser; piv; water
• PIV measurement of a jet from a gasper in an aircraft cabin mockup by Gouveia, João Henrique Antoniazzi de; Yanagihara, Jurandir Itizo (2021) - Piv experimental research on gasper jets interacting with the main ventilation in an aircrat cabin. Therefore, the present work is focused on the PIV measurement of the gasper airflow under the influence of a mixing ventilation system to evaluate jet features as velocity decay and entrainment ratio. Keywords: gasper; jet; piv; system
• Extended-POD based acoustic analysis of separated aerofoils via simultaneous time-resolved PIV and force measurements by Carter, Douglas William; Ferreira, Manuel; Ganapathisubramani, Bharathram (2021) - Motivated by the relationship between vorticity and sound production (Powell, 1995), the extended Proper Orthogonal Decomposition (EPOD, Borée, 2003) was used to reconstruct the pressure and unsteady pressure fields that are most correlated with three quantities: the out-of-plane vorticity, the partial unsteady lamb vector, and the forces and moments experienced by the foil. Pseudo color of the mean pressure coefficient field is shown in (b) with corresponding surface pressure distribution in (c) from the PIV (solid) and from dynamically matched RANS model (dashed). Keywords: fields; piv; pressure
• Uncertainty Estimation for Ensemble Particle Image Velocimetry by Ahmadzadegan, Adib; Bhattacharya, Sayantan; Ardekani, Arezoo M.; Vlachos, Pavlos P. (2021) - Abstract We present a novel approach to estimate the uncertainty in ensemble particle image velocimetry (PIV) measurements. Also, our analysis shows that ensemble MC consistently underestimates the uncertainty. Keywords: error; piv; uncertainty
• Using differential phase for 3D localization of tracer particles in digital inline holographic microscopy PIV/PTV (DIHM-PIV/PTV) by Ahmed, Asif; Sun, Bihai; Cadarso, Victor J.; Soria, Julio (2021) - Once a sequential pair of 3D volumes with particle fields is reconstructed these can be analysed using 3D cross-correlation analysis or a hybrid cross-correlation PIV/PTV to reveal the 3C-3D fluid velocity field Soria et al. (2014). In this new proposed method, the differential phase volume obtained from the experimental hologram is cross-correlated with the one is obtained from the simulated hologram of known particle position for the accurate localization of the seeding particles in the axial direction. Keywords: hologram; piv; reconstruction; volume
• Investigation of Best Practices in Volumetric Reconstruction for Plenoptic PIV by Sapkota, Bibek ; Kelly, Dustin ; Tan, Zu Puayen ; Thurow, Brian S. (2021) - Figure 3 shows the comparison of image based smoothing and volumetric smoothing on plenoptic reconstruction field. This paper analyzes the effect of smoothing in plenoptic reconstruction based on practices in multi- camera tomo reconstruction. Keywords: camera; piv; reconstruction; smoothing
• Investigation of the shear-layer instabilities in supersonic impinging jets using dual-time velocity measurements by Sikroria, Tushar ; Soria, Julio ; Karami, Shahram ; Sandberg, Richard ; Ooi, Andrew (2021) - The experimental setup for such measurements in supersonic impinging jets, followed by the determination of the relevant dynamical flow structures from the data, will be presented in the conference. Experi- ments in fluids 54:1578 Sikroria T, Soria J, Karami S, Sandberg RD, and Ooi A (2020) Measurement and analysis of the shear layer instabilities in supersonic impinging jets. Keywords: measurements; piv; soria; time
• Noise canceling to compute second order statistic from SPIV by Foucaut, Jean-Marc; Yuvaraj, Rakesh; Cuvier, Christophe (2021) - 101 102 0 0.5 1 1.5 ·10−2 ( ∂u′ ∂x )2 + 101 102 0.5 1 1.5 2 ·10−3 ( ∂v′ ∂x )2 + PIV sys1 PIV sys2 PIV denoised Figure 7: Effect of denoise on the derivatives of streamwise and wall-normal velocities at Reτ = 2220 3 Conclusion A method to denoise the statistics of turbulent flow is proposed in the present paper. The green vertical line shows the range of wall-distances for PIV experiment with Reτ = 2220, and the red vertical line shows the range of wall-distances for PIV experiment with Reτ = 3840 is approached one can observe that only the denoised statistics tend to follow that of DNS down to y+ = 10. Keywords: noise; piv; reτ; spiv; systems
• Development of micro soap bubble generator for PIV tracer using home stereolithography 3D printer by Shibata, Shu; Yamazaki, Takumi; Matsuda, Hisashi (2021) - Development of nozzle for generating micro soap bubble 2.1 Nozzle production using a hot-melt 3D printer As reported by Bosback et al. (2006) and Faleiros et al. (2019), the coaxial triple pipe structure is important for generating microbubbles. [mm] 0.05 Next, the suitable conditions for generating micro soap bubbles were adjusted under the condition that air was also supplied to the central pipe. Keywords: bubbles; diameter; measurement; micro; nozzle; pipe; piv; printer; soap
• PIV measurements of entrainment process of directly injected media in internal combustion engines by Abdelhameed, Elsayed; Aoyagi, Takahide; Tashima, Hiroshi; Tsuru, Daisuke (2021) - Figure 9 PIV measurements for spray in torch flame at 2msASOI Figure 10 shows the total air entrainment for air jet in the prechamber at different injection pressures 2, 3 and 4 MPa. +81-92-583-7592 Email: tasima@ence.kyushu-u.ac.jp Abstract PIV measurements have been successfully applied to various flow fields relating internal combustion engines such as in-cylinder air motion, air flow in an intake port, and even a discharging passage of an ignition plug. Keywords: air; entrainment; figure; gas; jet; piv; pressure; spray
• Simultaneous PIV and DIC Measurements in a Towing Tank Environment with a Flexible Hydrofoil by Jacobi, Gunnar; Nila, Alex (2021) - Figure 10: Temporal evolution of the hexapod motion, wing tip bending and total wing tip motion (top) and wing deformation with associated flow field two chord lengths behind the hydrofoil at selected phase angles (bottom). The combination of both measurement techniques allows for an accurate determination of tip vortex center positions with respect to the deformed wing and their evolution downstream of the wing. Keywords: figure; flow; hydrofoil; measurement; piv; tip; wing; wing tip
• Measurement of energy spectrum by using 100 eyes Tomographic PIV by Harada, Yuki; Saiga, Kazuto; Sakakibara, Jun (2021) - The images were evaluated by Tomographic PIV method to resolve three-dimensional velocity field. From the above, we can summarize that the advantage of Multiple Eye PIV over the 2C2D-PIV is effective when the number of mirrors is more than 40. Keywords: piv; spectrum
• Fluorescent PIV using Atomized Liquid Particles by Acharya, Adit S.; Lowe, K. Todd; Ng, Wing F. (2021) - The KR620 dye was used to dope Polystyrene Latex (PSL) microspheres, which are commonly used as PIV tracer particles [Raffel et al. (2018)]. Abstract It is shown that aerosolized fluorescent particles generated using a Venturi-type atomizer, from a solution of fluorescent Kiton Red 620 dye in a water/glycol fluid, provide effective flow seeding for fluorescent PIV. Keywords: dye; figure; fluorescent; layer; mie; mol; particles; piv; wall
• Validation of Multi-Frame PIV Image Interrogation Algorithms in the Spectral Domain by Beresh, Steven; Neal, Douglas; Sciacchitano, Andrea (2021) - These spectra produced using (a) (b) Fig. 3: Comparison of two-frame spectra from Fig. 1 to multi-frame correlation using a sliding sum-of-correlation (SoC) of N images and a Gaussian filter. to multi-frame correlation using a sliding sum-of-correlation (SoC) of N images and a top-hat filter. Keywords: correlation; data; fig; frame; frequency; measurement; noise; piv; spectra; time; wire
• Extending the Frequency Limits of "Postage-Stamp PIV" to MHz Rates by Beresh, Steven; Spillers, Russell; Soehnel, Melissa; Spitzer, Seth (2021) - This tends to smear out the subject matter being viewed; for PIV images, this will create ghost particles. Stokes numbers have been estimated as at most 0.05 based on a posteriori analysis of PIV measurements, which is sufficiently small to render particle lag errors negligible. Keywords: fig; frequency; image; khz; mhz; noise; piv; postage; rate; stamp; view
• smartPIV – an app for flow visualization by cross-correlation and optical flow using smartphones by Mäder, Patrick; Hüther, Jonas; Jeschke, Sebastian; Poll, Constanze; Otto, Henning; Cierpka, Christian (2021) - 14th International Symposium on Particle Image Velocimetry – ISPIV 2021 August 1–5, 2021 SmartPIV - an app for flow visualization by cross-correlation and optical flow using smartphones Patrick Mäder1∗, Constanze Poll1, Jonas Hüther1, Sebastian Jeschke1, Henning Otto2, Christian Cierpka2∗∗ 1 Technische Universität Ilmenau, Data-intensive Systems and Visualization Group, Ilmenau, Germany 2 Technische Universität Ilmenau, Institute of Thermodynamics and Fluid Mechanics, Ilmenau, Germany ∗ patrick.maeder@tu-ilmenau.de, ∗∗ christian.cierpka@tu-ilmenau.de In recent years smartphones considerably changed our communication and are used on a daily (or even every minute) basis especially by students without any difficulties. Flow visualization by mobile phone cameras. Keywords: app; flow; piv; smartphones; students
• Characterization of Non-linear Internal Waves Using PIV/PLIF Techniques by Mohaghar, Mohammad; Webster, Donald R. (2021) - Due to the significance of this phenomena, numerous investigations have been conducted to obtain sat- isfactory theoretical solutions for internal waves in several types of fluid systems. To date, most experimental studies for several types of internal waves have been performed using ultrasonic probes, conductivity probes, resistance-type wave gauges, or salinity-sensor-type wave gauges, as given by Davis and Acrivos (1967),Koop and Butler (1981),Michallet and Barthelemy (1998) and Umeyama (2002). Keywords: density; fluid; piv; waves
• High Speed PIV Measurements in Water Hammer by Capanna, Roberto; Bardet, Philippe M. (2021) - To the author knowledge the implementation of PIV measurements at this temporal resolution represent a first of a kind. A 60 mm Figure 5: Laser alignment on the impact area for PIV measurements. Keywords: chamber; hammer; measurements; piv; projectile; water; water hammer
• Reynolds stress tensor and pressure-related turbulence transport terms measured by time-resolved tomographic-PIV by Moreto, Jose Roberto; Liu, Xiaofeng (2021) - Measurement Science and technology 21:105401 De Kat R and Van Oudheusden B (2012) Instantaneous planar pressure determination from piv in turbulent flow. Assessment of pressure field calculations from particle image velocimetry measurements. Keywords: cavity; flow; liu; piv; pressure

• Uncertainty of PIV/PTV based pressure, using velocity uncertainty by Zhang, Jiacheng ; Bhattacharya, Sayantan ; Vlachos, Pavlos (2021) - The RMS of pressure error and uncertainty from velocity fields with different noise level The method was then applied to the experimental velocity measurement of a vortex ring acquired using plannar PIV [2]. [1] Zhang J, Bhattacharya S and Vlachos P P 2020 Using uncertainty to improve pressure field reconstruction from PIV / PTV flow measurements Exp. Keywords: error; pressure; uncertainty
• A stereoscopic PIV system for the Princeton Superpipe by Ding, Liuyang; Limacher, Eric; Gunady, Ian; Piqué, Alexander; Hultmark, Marcus; Smits, Alexander (2021) - Compressed air at higher pressure is driven through the nozzles to generate an aerosol, which is then carried into the Superpipe through a connecting tube. Legrand et al. (2017), for example, managed to obtain smaller modal diameters than us at low pressure differences (yellow-filled red stars on figure 2). Keywords: pipe; pressure; system; test
• Experimentally obtained velocity and pressure fields of an open channel flow around a cylinder using RIM-SPIV by Reeder, William Jeffery ; Moreto, Jose Roberto ; Liu, Xiaofeng; Tonina, Daniele (2021) - The method shows that mapping of the hydrodynamic fields around solids can be achieved experimentally with the use of low-cost and non-toxic fluids or solids coupled with suitable pressure field reconstructing algorithms. (a) (b) Figure 2: Sample mean velocity (left) and mean pressure (right, without accounting the body force) along the symmetry plane through the center of the cylinder. Keywords: cylinder; field; flow; liu; pressure
• Pressure reconstruction of a planar turbulent flow field within a multiply-connected domain with arbitrary boundary shapes by Liu, Xiaofeng; Moreto, Jose Roberto (2021) - For further validation, the code is also applied for pressure reconstruction from the DNS pressure gradient in the ambient flow field of a shock-induced non-spherical bubble collapse in water (Johnsen and Colonius, 2009). Sample results for pressure reconstruction within multiply-connected domains based on the Hopkins isotropic turbulence database are shown in Figure 2. Keywords: boundary; domain; integration; pressure; reconstruction
• Error propagation dynamics of velocimetry-based pressure field calculations (2): on the error profile by Faiella, Matthew ; MacMillan, Corwin G. J. ; Whitehead, Jared ; Pan, Zhao (2021) - Error in the reconstructed pressure field (εp) caused by concentrated error in the data field located at different locations (ε f = δ(x0,y0)). Figure 2: Error amplification ratio (Ar) and error profile in the pressure field εp when concentrated error (ε f = δ0.01L(x−x0) is introduced at different locations (x0)). Keywords: boundary; data; dirichlet; domain; error; error propagation; field; neumann; pressure; pressure field
• Gridless Determination of Aerodynamic Loads Using Lagrangian Particle Tracks by Mertens, Christoph; Costa Fernández, José L.; Sciacchitano, Andrea; van Oudheusden, Bas W.; Sodja, Jurij (2021) - For the pressure-based approach, flow measurements in the immediate vicinity of the wing are necessary. Contrary to most approaches in the published literature, the loads were not determined from ensemble-averaged data on a Cartesian grid, but instead by first determining the deformed shape of the wing from LPT measurements of structural mark- ers and then analyzing the discrete LPT flowfield data in a local coordinate system, which is given by the measured wing shape. Keywords: data; fig; flow; lift; lpt; lpt data; measurements; pressure; surface; wing
• Moving Surface Actuation, Effects of Frequency-based Shear Layer Excitation on the Response of a Bluff Body Wake by Singbeil, Matthew; Ghiroaga, Calin; Morton, Chris; Martinuzzi, Robert (2021) - Canada ∗ mrsingbe@ucalgary.ca Abstract The effect of actuation frequency, using moving surface actuation, is investigated for a square cylinder bluff body wake. The drag obtained using PIV measurements and Kochin’s formulation is consistent with trends observed for the base pressure as a function of actuation frequency. Keywords: actuation; circulation; drag; fig; frequency; pressure; rpm; shedding; vortex
• Separation Control of NACA0015 Airfoil using Plasma Actuators by Aiura, Akira; Kobayashi, Kentaro; Sakakibara, Jun (2021) - Surface pressure was monitored by pressure transducers through pressure taps on the upper surface of airfoil. However, such a predominance of the PA-off case is not maintained towards leading edge, i.e. the negative pressure value under the φ = π case exceeds others in a range from x = -0.1c to -0.2c, as indicated by PIV based pressure. Keywords: pressure

• Development and Uncertainty Characterization of Rotating 3D Velocimetry using a Single Plenoptic Camera by Moaven, Mahyar; Gururaj, Abbishek; Tan, Zu Puayen; Morris, Sarah; Thurow, Brian; Raghav, Vrishank (2021) - Figure 4: s-Coefficient values through a full revolution of calibration plate rotation (Gururaj et al. (2021)) Therefore, in the rotational implementation of DLFC, calibration images are acquired for volumes at relatively broad increments of azimuth angle and mapping functions are generated for any desired in-between angles using interpolation. Keywords: angle; azimuth; calibration; camera; field; plenoptic; rotating; rotation; uncertainty; volume
• Three-dimensional density measurements of a heated jet using laser-speckle tomographic background-oriented schlieren by Amjad, Shoaib; Soria, Julio; Atkinson, Callum (2021) - Defocus blurring must also be carefully managed, as the sensitivity Figure 2: Longitudinal slice through reconstructed density field ρ (kg/m3) at one time-step at y/D = 0. Using an optimised iterative tomographic reconstruction method Amjad et al. (2020), we demonstrate the suitability of tomographic laser-speckle BOS for the collection of turbulent density field statistics using a heated air jet. Keywords: background; density; field
• Flow Field Study of a Top Heated Immiscible Liquid Layer Adjacent to Ice by Farmahini Farahani, Hamed; Hayashi, Tatsunori; Sakaue, Hirotaka; Rangwala, Ali S. (2021) - In particular, presence of oil adjacent to ice can fundamentally alter melting of ice sheets by increase of energy absorption from the sunlight. Farahani, H. F., Torero, J. L., Jomaas, G., Rangwala, A., (2019) Scaling analysis of ice melting during burning of oil in ice-infested waters, International Journal of Heat and Mass Transfer, Volume 130, Pages 386-392. Keywords: field; flow; ice; liquid; melting
• Large-scale structures of scalar and velocity in a turbulent jet flow by Reijtenbagh, Jesse; Westerweel, Jerry; van de Water, Willem (2021) - Uniform concentration zones of an advected scalar are identified using cluster analysis. The edges of uniform concentration zones are correlated with the ridges of the past-time Lyapunov field, but not with those of the future-time Lyapunov field. Keywords: concentration; field; ftle; zones
• On the challenges of precise velocity measurements in vertical convective wall jets by Otto, Henning; Cierpka, Christian (2021) - b) Resulting vertical velocity field after merging. Figure 3: Resulting vertical velocity fields of the 7 measurements at different heights. Keywords: field; frame; measuring; storage

• Hilbert transform revisited – Proper orthogonal decomposition applied to analytical signals of flow fields by Kriegseis, Jochen ; Kinzel, Matthias ; Nobach, Holger (2021) - One possibility to automatically pair corresponding patterns with common POD algorithms is the immediate application of the POD method to complex data (see Pfeffer et al., 1990). As a final remark, the above insights and conclusions indicate that the Hilbert-transform based con- version of raw data to an analytical signal is an advantageous additional robust and straight forward pre- processing step to advance beyond the classical POD method. Keywords: complex; data; flow; hpod
• Uncertainty Quantification for PTV/LPT data and Adaptive Track Filtering by Janke, Thomas; Michaelis, Dirk (2021) - Within this contribution we want to present how to acquire measurement uncertainties for the position, velocity and acceleration for each data point along a trajectory by means of linear regression analysis tools. The proposed approach is applicable for polynomial filters of arbitrary lengths and orders. Keywords: data; filter; length; measurement; noise; polynomial; regression; uncertainty
• A network-based perspective on coherent structure detection from very-sparse Lagrangian data by Iacobello, Giovanni; Rival, David E. (2021) - While the Eulerian framework has been extensively adopted for CSD, Lagrangian coherent structures have recently received increasing attention, mainly driven by advancements in Lagrangian flow measurement techniques (Haller, 2015; Hadjighasem et al., 2017). Physica A: Statistical Mechanics and its Applications page 125476 Martins F, Sciacchitano A, and Rival D (2021) Detection of vortical structures in sparse lagrangian data using coherent-structure colouring. Keywords: data; flow
• A novel laboratory pushing the limits for optics-based basic turbulence investigations by Ribergaard, Simon Lautrup; Zhang, Yisheng; Abitan, Haim; Nielsen, Jakob Skov; Jensen, Niels Steenfeldt; Velte, Clara (2021) - (Right) Picture of the current preliminary version of the camera, LED and jet setup used for global jet measurements in four-dimensions. (Right) Current version of jet modulation mech- anism. Keywords: air; cells; data; equilibrium; experiment; figure; flow; jet; measurements; scales; test; turbulence
• Data reconstruction of homogeneous turbulence using Lagrangian Particle Tracking with Shake-The-Box and machine learning by Kim, Dong; Kim, Kyung Chun (2021) - FlowFit data was used as ground truth to train ML algorithm. We acknowledge Daniel Schanz, Florian Huhn, Sebastian Gesemann and Andreras Schröder (German Aerospace Center) for providing the LPT and FlowFit data, Daniel Garaboa-Paz (University of Santiago de Compostella) and Eberhard Bodenschatz (Max-Planck Institute for Dynamics and Self-Organization) are acknowledged for their contributions to the experiment References Keywords: anfis; data; flowfit
• Multi-spectral imaging for Thermochromic Liquid Crystal based Particle Image Thermometry: A proof of concept by Käufer, Theo; Moller, Sebastian; Rosenberger, Maik; Notni, Gunther; Cierpka, Christian (2021) - Likewise, for optical temperature measurements in fluids, several different methods have been developed and are applied depending on the field of application, expected temperature range, and re- quired uncertainty. An alternative approach is to use temperature-sensitive seeding particles for temperature measurement. Keywords: camera; color; data; figure; filter; range; temperature

• Investigating Optimal Training and Uncertainty Quantification for CNN-based Optical Flow by Kurinara, Daiki; Blois, Gianluca; Sakaue, Hirotaka; Schiavazzi, Daniele (2021) - The first newly tested training approach consisted of multiple sessions where finer image resolution levels are progressively activated at each successive stage (staged training, see Fig. 1(a)). The network progressively identifies flow features in a coarse-to-fine resolution pipeline, starting from level 6 (coarser resolution) to level 2 (finer resolution). Keywords: flow; image; liteflownet; training
• An Infrared Quantitative Imaging Technique (IR-QIV) for Remote Sensing of River Flows by Cowen, Edwin Alfred; Schweitzer, Seth Avram (2021) - Figure 1: Infrared image of the water surface of a river (Sutter Slough, California, USA). We describe considerations related to acquisition of infrared images for IR-QIV (camera selection, effects of environmental conditions on image quality and suitability for velocimetry), and also aspects that are relevant to large-scale, image-based, velocimetry methods, regardless of the spectral range of the images (i.e., IR or visible-light), in particular for images acquired at oblique viewing angles. Keywords: image; river
• Visualization and Quantification of the Cerebral Microcirculation using Contrast-enhanced Ultrasound Particle Tracking Velocimetry by Zhang, Zeng ; Hwang, Misun ; Kilbaugh, Todd J.; Sridharan, Anush; Katz, Joseph (2021) - However, CEUS images recorded by different ultrasound systems, contrast agents, and imaging settings, as well as recoded at various depth and organs, involve diverse noise levels, backgrounds, and bubble image morphologies. Several postprocessing techniques have been developed to quantify the flow parameters based on CEUS images, including ultrasound imaging velocimetry or echo-PIV (Crapper et al. 2000; Kim et al. 2004; Poelma 2017; Zhang et al. 2020), and echo- particle tracking velocimetry (Sampath et al. 2018; Jeronimo et al. 2020), which is also referred to as Ultrasound Localization Microscopy (ULM) in the CEUS community (Siepmann et al. 2011; Keywords: bubble; ceus; et al; fig; flow; image; imaging; net; tracking; training; ultrasound; velocimetry

• TrackAER: Real-Time Event-Based Particle Tracking by Rusch, Alexander; Roesgen, Thomas (2021) - Alternatively, events can be processed in a fully sequential manner, i.e., “event-by-event”, keeping the precise timing information and ordering of the events. Gallego et al., 2020) operate fundamen- tally different from frame-based cameras: Each pixel of the sensor array reacts asynchronously to relative brightness changes creating a sequential stream of events in address-event representation (AER). Keywords: cameras; event; time; tracking; vision

• Volumetric Lagrangian Particle Tracking, Air water interface, insect locomotion, surface tension by Steinmann, Thomas; David, Larent; Braud, Patrick; Casas, Jérôme (2021) - For instance, the side illumination of a wavy air–water interface often results in the appearance of shadow patches at the surface, due to wave crests. These species include water striders, a family of insects from the order Hemiptera that has an almost unique ability to walk on the surface of the water without penetrating it. Keywords: flow; interface; leg; surface; water
• Energy spectra of Sub-Surface Velocity Fields Beneath Faraday Waves by Colombi, Raffaele; Rohde, Niclas; Schlüter, Michael ; von Kameke, Alexandra (2021) - Furthermore, the fraction of flow kinetic energy in the vertical direction is found to peak inside a layer of approximately 10 mm (one Faraday wavelength) below the fluid surface. Moreover, recent studies discovered the existence of a horizontal velocity field at the fluid surface, called Faraday flow, which was shown to ex- hibit an inverse energy cascade and thus properties of two-dimensional turbulence (von Kameke et al., 2011, 2013; Francois et al., 2013). Keywords: energy; faraday; surface; waves
• PIV Measurements of the Wake Formation from a Rough Flat Plate by Lawrence, Sean; Atkinson, Callum; Soria, Julio (2021) - Two-component two-dimension particle image velocimetry (2C-2D PIV) is used to investigate the effect of surface roughness on the formation of large scale structures in the near wake of a thin flat plate. Both high-speed and low-speed, high-resolution PIV setups have been used to investigate the effect of surface roughness on the boundary layer and the near wake of the plate to gain insight into the underlying physical connection between these regions. Keywords: layer; roughness; surface; wake

• Mounting and support for pseudo biaxial Scheimpflug focusing for unity-magnification, high-speed particle velocimetry by Ribergård, Simon Lautrup; Olesen, Peder Jørgensgaard; Jensen, Niels Steenfeldt; Nielsen, Jakob Skov; Velte, Clara Marika (2021) - The newly designed mounts allow for a broader range of solutions for combinations of positioning and alignment than traditional Scheimpflug mounts. As it turns out, we’re now convinced that there are no such thing as true biaxial Scheimpflug focusing, only what we have dubbed “pseudo biaxial” Scheimpflug focusing. Keywords: camera; focusing; mount; scheimpflug

• Numerical Uncertainty in Density Estimation for Background Oriented Schlieren by Zhang, Jiacheng; Rajendran, Lalit; Bane, Sally; Vlachos, Pavlos (2021) - The displacement fields were used to calculate the depth averaged density gradient field [2] L. K. Rajendran, J. Zhang, S. Bhattacharya, S. P. M. Bane, and P. P. Vlachos, “Uncertainty quantification in density estimation from background-oriented Schlieren measurements,” Meas. Keywords: density; error; uncertainty

• Combining high-speed planar PIV and motion tracking of a flexible cylinder in cross-flow by Gundersen, Diego George; Christensen, Kenneth Thor; Blois, Gianluca (2021) - Novel environment enables piv mea- surements of turbulent flow around and within complex topographies. 2 Methods Laboratory experiments were performed in the Refractive Index-Matched (RIM) flow facility at Notre Dame (Blois et al., 2020). Keywords: cylinder; flow; fluid; motion
• Influence of span-wise coherence on the acoustic radiation in a cylinder wake by Siegel, Lars ; He, Guosheng ; Henning, Arne ; Mulleners, Karen (2021) - for Aerodyn. & Flow Tech., Göttingen, Germany 2 Institute of Mechanical Engineering, École polytechnique fédérale de Lausanne (EPFL), Switzerland 3 School of Astronautics, Beijing Institute of Technology, China ∗ arne.henning@dlr.de Abstract The aim of this study is to detect and visualise the influence of span-wise coherence on propagating sound waves emanating from a flow around circular cylinders with span-wise variations of the local radius. Cylinders with different span-wise variations are investigated as illustrated in fig. Keywords: cylinder; flow; span
• Volumetric Lagrangian particle tracking measurements of jet impingement on convex cylinder by Kim, Mirae; Schanz, Daniel; Novara, Matteo; Schröder, Andreas; Kim, Kyung Chun (2021) - Shake-The-Box: Lagrangian particle tracking at high particle image densities. Therefore, in this study, three-dimensional flow structures of a round jet impinging on a convex cylinder surface were measured using volumetric Lagrangian particle tracking (LPT). Keywords: cylinder; jet
• Wake behind circular cylinder excited by spanwise non-uniform disturbances by Kamiyama, Takumi; Ino, Mizuki; Yokota, Yudai; Sakakibara, Jun (2021) - Figure 2 shows surface of constant vorticity magnitude and vortex lines under St =1.09 and φ = π case. 4200 Figure 2 Surfaces of constant vorticity magnitude and vortex lines extracted from a phase averaged velocity field line under St =1.09 and φ = π case. Keywords: cylinder
• Application of SPOD analysis to PIV data obtained in the wake of a circular cylinder undergoing vortex induced vibrations by O'Neill, Christopher Mark; Schubert, Yannick; Sieber, Moritz; Martinuzzi, Robert ; Morton, Chris (2021) - Further with N f = N, SPOD is equivalent to the discrete fourier transform (DFT). Low order models based on the first eight POD and SPOD modes were compared, and it was found that the filtering operation in SPOD removes the uncorrelated stochastic energy component of the POD modes while producing a comparable representation of the coherent deterministic part of the wake dynamics. Keywords: cylinder; dynamics; figure; frequency; mode; spod; vortex; wake

• Phase separation and flow measurement of dilute bubbly jet with 2-D PIV and LIF by Seo, Hyunduk; Kim, Kyung Chun (2021) - In this study, we investigate bubbly jet with 2-D PIV and LIF techniques, which can analyze the structure of bubbly jet inside the core region of the bubbly jet with a low void fraction (Dulin et al., 2012). Figure 3: Radial population of bubbles with height 4 Conclusions Each phase in bubbly jet is successfully measured by the combination of PIV and LIF. Keywords: jet; phase
• Flow field of impinging sweeping jets by Paolillo, Gerardo; Greco, Carlo Salvatore; Cardone, Gennaro; Astarita, Tommaso (2021) - 14th International Symposium on Particle Image Velocimetry – ISPIV 2021 August 1–5, 2021 Flow field of impinging sweeping jets G. Paolillo1∗, C. S. Greco1, G. Cardone1 and T. Astarita1 1 University of Naples “Federico II”, Department of Industrial Engineering, Naples 80125, Italy ∗gerardo.paolillo@unina.it Sweeping jets are oscillating jets generated by fluidic oscillators, i.e., devices designed to produce an oscillation of the flow without the use of any moving parts (Raghu, 2013). Experiments in Fluids 54:1–11 Seo J, Zhu C, and Mittal R (2018) Flow physics and frequency scaling of sweeping jet fluidic oscillators. Keywords: flow; jet; jets
• 3D Particle Tracking Velocimetry applied to droplets generated by breaking waves by RAMIREZ DE LA TORRE, Reyna Guadalupe; Jensen, Atle (2021) - Different wave heights were used to obtain different breaking stages and the wall height is lower than the wave height in all cases. The jet formation at wave impact and jet break-up into droplets have been less studied because of its complexity. Keywords: droplets; experiment; figure; jet; shows; size; wall; wave; wind

• An Intensity-based and a lifetime-based PSP imaging method with enhanced sensitivity by Someya, Satoshi ; Yamashita, Shogo ; Munakata, Tetsuo ; Ito, Hiroshi (2021) - As shown in figs.3, proposed methods had higher pressure sensitivity than those of standard methods. However, measurement resolution and accuracy deteriorate when quantum efficiency or lifetime decrease under high pressure or high temperature conditions. Keywords: method

• Measurements of intracrater flow dynamics utilizing a mound-bearing crater in a refractive index matched environment by Gundersen, Diego George; Christensen, Kenneth; Blois, Gianluca (2021) - 1 University of Notre Dame, Department of Aerospace and Mechanical Engineering, Notre Dame, USA 2 Illinois Institute of Technology, Depts. of Mechanical, Materials & Aerospace Engineering and Civil, Architectural & Environmental Engineering, Chicago, USA 1 Introduction The processes controlling crater mound formation are the subject of ongoing research (Bennett and Bell III, 2016). This gives evidence that the idealized geometry can be used as an analogue to geometries based on real impact craters. Keywords: crater; flow; measurements; plane
• Rayleigh-Bénard convection in air: out-of-plane vorticity from stereoscopic PIV measurements by Valentina, Valori; Thieme, Alexander; Cierpka, Christian; Schumacher, Joerg (2021) - Abstract We present results from stereoscopic PIV measurements in a Rayleigh-Bénard convection (RBC) cell filled with (compressed) air at Rayleigh numbers: 14th International Symposium on Particle Image Velocimetry – ISPIV 2021 August 1–5, 2021 Rayleigh-Bénard convection in air: out-of-plane vorticity from stereoscopic PIV measurements V. Valori1∗, A. Thieme1, C. Cierpka1, J. Schumacher1,2 1 Technische Universität Ilmenau, Institute of Thermodynamics and Fluid Mechanics, D-98684 Ilmenau, Germany 2 New York University, Tandon School of Engineering, New York City, NY 11201, USA ∗ valentina.valori@tu-ilmenau.de Keywords: measurements; rayleigh

• PIV measurement of turbulence over a streamwise preferential porous medium by Morimoto, Mahiro; Okazaki, Yuki; Kuwata, Yusuke; Suga, Kazuhiko (2021) - Understanding and modelling turbulence over and inside porous media. J Fluid Mech 822:186–201 Suga K, Okazaki Y, and Kuwata Y (2020) Characteristics of turbulent square duct flows over porous media. Keywords: figure; flow; medium; reb; solid; wall

• Analysis of the Contribution of Large Scale Motions to the Skin Friction of a Zero-Pressure-Gradient Turbulent Boundary Layer Using the Renard-Deck Decomposition by Sun, Bihai; Shehzad, Muhammad; Jovic, Daniel; Cuvier, Christophe; Willert, Christian; Ostovan, Yasar; Foucaut, Jean-Marc; Atkinson, Callum; Soria, Julio (2021) - The second term, C fb , represents the production of the turbulent kinetic energy extracted from the mean streamwise kinetic energy and is the term of relevance in the analysis of the contribution of LSMs. This results show that LSM dominated snapshots results in an increase of C fb , indicating that the LSMs are a significant contributor to the turbulent production term in the RD decomposition of the skin friction. Keywords: decomposition; layer; mean; streamwise

• Super-large-scale flow visualization using natural snowfall for the study of utility-scale wind turbine flows by Abraham, Aliza; Hong, Jiarong (2021) - These findings have demonstrated that near wake flows, though highly complex, can be predicted with sub- stantial statistical confidence using information readily available from current utility-scale turbines. Figure 1: Sample images of snow particle patterns used for flow visualization and SLPIV measurements of (a) the bottom blade tip vortices, (b) turbine nacelle wake, (c) tower vortex tubes, (d) atmospheric flow approaching the turbine, (e) near-wake flow at the tower plane, and (f) near-wake flow at the plane normal to the flow direction. Keywords: flow; scale; turbine; wake
• TR-PIV in highly pulsatile flow: pulsation frequency and wake dynamics case study by Carr, Ian A.; Plesniak, Michael W. (2021) - flow flow vortex ring arch vortex image arch vortex Figure 7: Conceptual comparison of a vortex ring produced with the traditional, sharp-edged piston-driven vortex generator and the arch vortex in the wake of a hemisphere in pulsatile flow. This conceptual overview provides a framework for understanding the interaction between pulsatile flow and surface-mounted obstacles. Keywords: figure; flow; vortex; wake

• PIV and deformation measurements on the rotor blade of a rotating, scaled model wind turbine with flexible blades under tailored inflow conditions by Wester, Tom T. B.; Kröger, Lars; Langidis, Apostolos; Nietiedt, Simon; Rofallski, Robin; Goering, Martina; Luhmann, Thomas; Peinke, Joachim; Gülker, Gerd (2021) - Physical Review Letters 125:154503 Nietiedt S, Goering M, Willemsen T, Wester T, Kröger L, Guelker G, and Luhmann T (2019) Measurement of fluid-structure interaction of wind turbines in wind tunnel experiments: Concept and first results.. International Archives of the Photogrammetry, Remote Sensing & Spatial Information Sciences Spinato F, Tavner PJ, Van Bussel G, and Koutoulakos E (2009) 14th International Symposium on Particle Image Velocimetry – ISPIV 2021 August 1–5, 2021 PIV and deformation measurements on the rotor blade of a rotating, scaled model wind turbine with flexible blades under tailored inflow conditions Tom T. B. Wester1∗, Lars Kröger1, Apostolos Langidis1, Simon Nietiedt2, Robin Rofallski2, Martina Goering2, Thomas Luhmann2, Joachim Peinke1, Gerd Gülker1 1 University of Oldenburg, ForWind - Institute of Physics, 26129 Oldenburg, Germany 2 Jade University of Applied Sciences, Institute of Applied Photogrammetry and Geoinformatics (IAPG), 26121 Oldenburg, Germany ∗ tom.wester@uni-oldenburg.de Abstract Wind turbines face harsh inflow conditions when operating in the atmospheric boundary layer or in the wake of other wind turbines. Keywords: blade; flow; turbine; wind

• An Experimental Investigation on the Wind-driven Runback Motion of Water Droplets over Solid Surfaces with Different Wettabilities by Ma, Liqun; Zhang, Zichen; Hu, Hui (2021) - It is of fundamental importance to understand the wind-driven runback behavior of water droplets over surfaces treated with different coatings, since the corresponding knowledge would be very helpful and essential to develop more efficient anti-/de-icing systems for aircraft icing protection. SHS always has a hierarchical structure which is similar to the lotus leaf, and water droplets on SHS appear as water beads which can easily roll off the surface by wind or gravity before frozen. Keywords: surfaces; water

• Experimental investigation on flow structures of steadily translating low-aspect-ratio wings in low Reynolds number flow by Zhu, Yichen; Wang, Jinjun (2021) - However, the LEVs cannot be identified from the time-averaged flow fields for the cases of NST model. The detected Γ1 peaks are fitted by Gaussian model to locate WTV centers more precisely. Keywords: fig; flow; model

• Development of an Optical set-up for 3D PIV with a Large Volume by Abitan, Haim; Velta, Clara Marika; Zhang, Yisheng; Ribergård, Simon Lautrup; Nielsen, Jakob Skov (2021) - (b) shows the experimental set-up of laser beam scanning by an AOM. Outgoing laser beam First orderBragg diffracting beams Incominglaser beam Acoustic wavelength � Piezoelectric transducer Density waves in the optical crystal (a) Acousto-optic modulator Off-axis parabolic mirror Laser (b) Figure 9: (a) illustrates the principle of Bragg diffraction from an AOM. Keywords: beam; density; laser; laser beam; mirror; power; power density; scanning; volume
• A novel method to accurately align the laser sheet for planar and stereoscopic PIV by Shehzad, Muhammad; Lawrence, Sean; Atkinson, Callum; Soria, Julio (2021) - Experiments in fluids 39:267– 280 Willert C (1997) Stereoscopic digital particle image velocimetry for application in wind tunnel flows. These PDs, connected to a multi-channel oscilloscope, detect the intensity of laser light falling on them through 1 mm holes. Keywords: calibration; laser; sheet; target

• Experimental Study of Darrieus Turbines in Confined Free-Surface Flows by Kara Mostefa, Larbi; Chatellier, Ludovic; Thomas, Lionel (2021) - For the higher incident speed V=0.909 m/s (Froude number 𝐹𝑟𝐼𝐼= 0.36), the best performance of prototype 1 (model Blades and rigid assembly) has been identified for a reduced speed λ=2.25, for a COP=38%. Prototype 1: Rigid blades and assembly. Keywords: blades; darrieus; figure; prototype; turbine

• Characterisation of vortex shedding on a hydrofoil using PIV measurements by Bonnard, Hervé; Chatellier, Ludovic; David, Laurent (2021) - The data were acquired at very low Reynolds number which are not often covered for such hydrofoil and at four angles of attack ranging from 2◦ to 30◦. A multi-frame PIV method was applied to evaluate the time resolved flow fields using a Fluid Trajectory Evaluation based on an Ensemble-averaged cross-correlation (FTEE) technique, see Jeon et al. (2014). Keywords: angle; attack; flow; hydrofoil

• Intermittency effects in single- and multi-phase flow and anomalous transport in heterogeneous porous media by Penko, Zoë ; Li, Yaofa ; Bolster, Diogo ; Christensen, Kenneth T. (2021) - 14th International Symposium on Particle Image Velocimetry Intermittency effects in single- and multi-phase flow and anomalous transport in heterogeneous porous media Zoë Penko1, Yaofa Li1,2, Diogo Bolster1,3, and Kenneth T. Christensen1,3,4 1University of Notre Dame, Department of Aerospace and Mechanical Engineering 2Now at Montana State University, Department of Mechanical and Industrial Engineering 3University of Notre Dame, Department of Civil and Environmental Engineering and Earth Sciences 4Now at Illinois Institute of Technology, Armour College of Engineering Introduction Multi-phase flow and transport in porous media is prevalent in a wide range of challenging fluid mechanics problems related to sustainability, energy, and the environment. Morales et al., n.d.), but the case of multi-phase flow has yet to receive much study due to challenges faced in both simulations and experiments. Keywords: flow; intermittency; phase
• Micro-PIV Measurements of Multiphase Flow in Deforming Porous Media Subject to Mineral Dissolution by Molla, Razin; Raventhiran, Nishagar; Li, Yaofa (2021) - 14th International Symposium on Particle Image Velocimetry – ISPIV 2021 August 1–5, 2021 Micro-PIV Measurements of Multiphase Flow in Deforming Porous Media Subject to Mineral Dissolution R. Molla1, N. Raventhiran1, Y. Li1∗ 1 Montana State University, Mechanical&Industrial Engineering, Bozeman, USA ∗ yaofa.li@montana.edu Abstract Mineral dissolution is studied in novel calcite-based porous micromodels under single- and multiphase con- ditions, with a focus on the interactions of mineral dissolution with pore flow. To this end, mineral dissolution is studied in novel calcite-based porous micromodels under single- and multiphase conditions, with a focus on the interactions of mineral dissolution with pore flow. Keywords: dissolution; flow; mineral; phase

• On the determination of 3D position and orientation of spheroidal particles using defocusing and deep learning by Rossi, Massimiliano (2021) - A defocus- ing method that has potential to measure non-spherical particles is the General Defocusing Particle Tracking (Barnkob and Rossi (2020)) which is based on pattern recognition and can be conceptually extended to more complex tasks by extending the reference library of particle images, including not only spherical particles at different depth positions, but also non-spherical particles at different orientations. Therefore, the problem reduces to the determination of z, α, and β for a set of single particle images. Keywords: images; particles
• Tracking particles in Poiseuille flow for several pipe diameters in three dimensions by Sridharan, Sudarshan; Poelma, Christian (2021) - This is preferable as we intend to locate large particles slowly migrating over a long distance: typically cross-stream velocities are less than 5% of its streamwise velocity. Based on our observations, particles are observed to accumulate at two radial locations (≈ 0.8R and 0.6R from pipe axis) at higher Reynolds numbers (Reb > 700), with larger particles (D/d = 6) preferably staying at the inner location. Keywords: particles; pipe; reb; reynolds

• An experimental investigation on stall flutter over a vertically mounted rigid finite wing by Soares, Renan Francisco; Karasu, Ilyas; Ganapathisubramani, Bharath (2021) - This work presents the experimental investigation of rigid wing setup in a closed-circuit wind tunnel having 2.1 m × 1.5 m test section. Figure 1: Wing system and ‘shake-the-box’ hardware setup for structural analysis. Keywords: tracking; wing

• Robust approach to monitoring Lagrangian transport in very large volume by Kaiser, Frieder; Haramis, Andreas; Galler, Joshua; Rival, David E. (2021) - Figure 1: (a) Sketch of the experimental set-up; (b) bubble images recorded at t1 and t4 with varying bubble- image size (db); (c) linear optics producing the bubble images of size dB dependent on bubble size (DB) and position (o); and (d) bubble-image size (dB) in pixels as a function of object distance o with a f = 35mm lens and a pixel size of 10µm. Large soap bubbles (DB ≈ 30mm) are illuminated by a light source placed perpendicular to both cameras. Keywords: bubble; figure; size

• Fluid structure interactions of a pitching wing at high angle of attack by Acher, Gwenael; Braud, Patrick; Chatellier, Ludovic; Thomas, Lionel; David, Laurent (2021) - 1 Introduction In high incidence conditions, wings are subjected to large vortex detachments which promote the dynamic stall leading to a sudden drop in lift. 14th International Symposium on Particle Image Velocimetry – ISPIV 2021 August 1–5, 2021 Fluid structure interactions of a pitching wing at high angle of attack G. Acher1∗, Patrick Braud1∗, Ludovic Chatellier1∗, Lionel Thomas1∗, Laurent David1∗ 1 Institut PPrime, UPR 3346, CNRS-Universit de Poitiers-ENSMA, France ∗ laurent.david@univ-poitiers.fr Abstract This paper deals with the study of the flow around a pitching wing at high angle of attack. Keywords: flow; pitching; wing

• Quantification of Brownian motion under presence of flow using particle diffusometry by Lee, Dong Hoon; Wereley, Steven T. (2021) - However, with non-uniform flows, we see greater deviations from theoretical values due to the gradient of the flow. 14th International Symposium on Particle Image Velocimetry – ISPIV 2021 August 1–5, 2021 Quantification of Brownian motion under presence of flow using Particle Diffusometry D. Lee1, S. T. Wereley1∗ 1 Purdue University, School of Mechanical Engineering, West Lafayette, USA ∗ wereley@purdue.edu Abstract Particle diffusometry (PD), a quantification method for the Brownian motion, is performed by recording temporally sequential images and using correlation analysis to obtain an ensemble diffusion coefficient for all particles captured in the imaging region (Clayton et al., 2017). Keywords: coefficient; correlation; diffusion; flow

• On the unsteady dynamics of synthetic leaves: Laboratory experiments using synchronized PIV and DIC by Wing, Lai; Troolin, Dan; Cheng, Shyuan; Sun, Jiao; Chamorro, Leonardo (2021) - ABSTRACT The unsteady 3D dynamics of various synthetic leaves and the induced turbulence are systematically studied experimentally for representative Cauchy numbers in a wind tunnel under nearly uniform incoming flows. Abstract Submission Template On the unsteady dynamics of synthetic leaves: Laboratory experiments using synchronized PIV and DIC Lai Wing1, Dan Troolin1, Shyuan Cheng,2 Jiao Sun, 2 and Leonardo P. Chamorro2 1 TSI Incorporated, USA. Keywords: force; leaf

• PIV measurements in a turbulent boundary layer overlying a spanwise heterogeneous roughness by Yao, Rongnan; Christensen, Kenneth (2021) - In a particular scenario, when the surface heterogeneity is predominantly in the spanwise direction of the flow, this roughness heterogeneity can generate secondary flow in cross flow plane which is very different from smooth-wall or homogeneous rough-wall boundary layers. References Anderson W, Barros JM, Christensen KT, and Awasthi A (2015) Numerical and experimental study of mech- anisms responsible for turbulent secondary flows in boundary layer flows over spanwise heterogeneous roughness. Keywords: flow; roughness; streamwise

• Experimental investigations of the turbulent/non-turbulent interface over surface with spanwise heterogeneity by Long, Yanguang; Wang, Jinjun; Pan, Chong (2021) - Background colormap: streamwise velocity; black vectors: spanwise and vertical velocity; blue curve: TNTI location. It can be observed that the p.d.f. of TNTI height above LMP shows a negative skewness, while the p.d.f. above HMP skews positively. Keywords: height; layers; spanwise; tnti

• Flow characteristics analysis for flow past the porous spheres: wake structures and drag force coefficients by Ma, Likun; Kashanj, Sina; Xu, Shuliang; Ye, Mao; Nobes, David (2021) - In this study, flow fields of porous spheres with Darcy numbers ranging from [0,10−3] were captured at Re = 400,600,800,1000,1200,1400. However, it’s difficult for numerical simu- lations to determine appropriate fluid-porous interface boundary conditions for porous spheres, which can significantly affect the simulation results. Keywords: flow; sphere; stagnation

• DPTV-based analysis of the flow-structure/wall-shear interplay in open wet clutches by Leister, Robin; Kriegseis, Jochen (2021) - mytitle 14th International Symposium on Particle Image Velocimetry – ISPIV 2021 August 1–5, 2021 DPTV-based analysis of the flow-structure/wall-shear interplay in open wet clutches Robin Leister1∗, Jochen Kriegseis1 1 Institute of Fluids Mechanics (ISTM), Karlsruhe Institute of Technology (KIT) The main interplay between torque and fluid flow in open wet clutches has been analyzed by Leister et al. (2020) in a dimensionless way. Keywords: drag; flow; groove; torque

• An Experimental Study of Unsteady Heat Transfer and Phase Changing Process Upon Impacting of Ice Crystals onto Heated Surfaces Pertinent to Aero-Engine Icing Phenomena by Hu, Haiyang; Tian, Linchuan; Hu, Hui (2021) - Since ice particles were believed to simply bounce off from the exposed surfaces of aero-engine components, ice crystals in the clouds were initially considered not to pose a threat to aviation safety. In the present study, a series of experimental investigations were conducted to elucidate the underlying physics of the dynamic ice accretion process pertinent to ice crystal icing phenomena. Keywords: ice; icing

• Tomographic PIV measurement of a re-entrant jet in a cavitating venturi by Gawandalkar, Udhav Ulhas; Poelma, Christian (2021) - There have been several attempts to measure the velocity of the re-entrant flow to get insight into the physics of re-entrant flow and its contribution to cloud shedding. This in turn provides better insight into the role of re-entrant flow in periodic cloud shedding. Keywords: cavity; figure; flow

• Towards capturing a database of respiratory exhalations from flow visualisations by Bahl, Prateek; de Silva, Charitha; MacIntyre, C Raina; Chughtai, Abrar Ahmad; Doolan, Con (2021) - Studies in the past have utilised flow visualisation techniques to understand the dynamics of res- piratory flows but most of them provide only qualitative data on respiratory droplets and do not provide sufficient detail to estimate accurate flow velocities (Bourouiba et al., 2014; Vansciver et al., 2011; Scharf- man et al., 2016). Journal of Fluid Mechanics 745:537–563 Scharfman B, Techet A, Bush J, and Bourouiba L (2016) Visualization of sneeze ejecta: steps of fluid fragmentation leading to respiratory droplets. Keywords: droplets; exhalations; sydney

• Bubble PIV technique to measure the velocity field of a free-swimming California sea lion by Leftwich, Megan Clare ; Perrotta, Gino ; Fish, Frank E (2021) - 4 Conclusions The flowfield of swimming California sea lions was measured by adapting and advancing bubble PIV tech- niques. 2 Methods Data collection: Measurements were taken at Science Learning and Exploration With The Help of Sea lions (SLEWTHS) in Moss Landing, California. Keywords: fig; flow; sea

• PIV measurement of complex flow characteristics in open-cell metal foam replica by Kim, Minsin; Kim, Youngwoo; Hosseini, Sajjad; Kim, Kyung Chun (2021) - Uniform upstream flow is divided by the pore network of metal foam and it is found that there are flow disturbances induced by metal foam structure even at a laminar inlet condition. The characteristics of metal foam internal flow with a laminar flow inlet condition were studied by Moon et al. (2018). Keywords: flow; foam; metal

• Particle Image Velocimetry Measurements of a Dry Powder Inhaler Flow by Chaugule, Vishal; dos Reis, Larissa Gomes; Fletcher, David F.; Young, Paul M.; Traini, Daniela; Soria, Julio (2021) - Figure 1: DPI model examined and schematic of the experimental set-up A common design feature in several DPI devices is the provision of tangential inlets to generate a swirling inhalation flow for the entrainment and de-agglomeration of the drug powder. These flow mechanisms are complex as they depend on the device design, inhalation flow rate, and the properties of the dry powder formulation used. Keywords: dpi; flow; mouthpiece; outside

• Cross-plane stereo-PIV measurements in a refractive-index-matched environment of flow associated with barchan dunes immersed in a turbulent boundary layer by Bristow, Nathaniel; Blois, Gianluca; Best, James; Christensen, Kenneth (2021) - 14th International Symposium on Particle Image Velocimetry – ISPIV 2021 August 1–5, 2021 Cross-plane stereo-PIV measurements in a refractive-index-matched environment of flow associated with barchan dunes immersed in a turbulent boundary layer N. R. Bristow1, G. Blois1, J.L. Best2, K. T. Christensen1,3∗ 1 University of Notre Dame, Department of Aerospace and Mechanical Engineering, Notre Dame, IN, USA 2 University of Illinois at Urbana-Champaign, Departments of Geology, Geography and GIS, Mechanical Science and Engineering and Ven Te Chow Hydrosystems Laboratory, Urbana-Champaign, IL, USA 3 Illinois Institute of Technology, Department of Mechanical, Materials, and Aerospace Engineering, Chicago, IL, USA ∗ Kenneth.Christensen@iit.edu 1 Introduction Barchan dunes are crescent-shaped bedforms that form in aeolian (i.e., wind-driven) environments (includ- ing both Earth and other planets, such as Mars) as well as subaqueous environments. In this study, the coherent structures formed in the wakes of barchan dunes are investigated using mea- surements of the flow over fixed-bed (i.e., solid) barchan models, both in the wake of an isolated barchan and the interdune region between interacting barchans (Fig. 1(a)). Keywords: barchan; dunes; flow

• Flow Field around the Badminton Shuttlecock during Flipping Motion by Sakurai, Yuki; Nakagawa, Kenichi ; Hasegawa, Hiroaki (2021) - Figure 2: Angular response of shuttlecock in turnover process O.S. angle 0 10 velocity[m/s] (b) α = -24.4° t = 0.081 s (c) α Calvin S.H. Lin., C. K. Chua and J. H. Yeo, Turnover stability of shuttlecocks – Transient angular response and impact deformation of feather and synthetic shuttlecocks. Keywords: flow; shuttlecock

Epilogue

For more detail, about this study carrel, see the computed home page. For more detail about study carrels in general, see the read me file.

Created: 2025-12-23