14th International Symposium on Particle Image Velocimetry – ISPIV 2021
August 1–5, 2021

Measurement of Lagrangian Tracks in a 3 L Stirred
Tank Reactor using 4D Particle Tracking Velocimetry

with Shake-the-Box
J. Fitschen1∗, A.v. Kameke2, S. Hofmann1, M. Hoffmann1, M. Schlüter1

1 Hamburg University of Technology, Institute of Multiphase Flows, Hamburg, Germany
2 Hamburg University of Applied Science, Department of Mechanical Engineering and Production,

Hamburg, Germany
∗ corresponding: juergen.fitschen@tuhh.de

Abstract
Stirred tank reactors are widely used in the chemical industry and bioprocess engineering and, consequently,
a large number of scientific publications deal with the characterization of those apparatuses. However, there
is very little information about the flow conditions. This is mostly due to the fact that these apparatuses
are generally made of stainless steel, which restricts optical access. Furthermore, three-dimensional flow
field measurements are still not trivial and involve costly equipment, therefore, investigations often reduce
to two-dimensional PIV measurements. Nevertheless, recent works (Rosseburg et al., 2018; Taghavi and
Moghaddas, 2020; Kuschel et al., 2021) impressively show the formation of compartments which hinder
and delay mixing. However, these measurements are based either on instantaneous concentration profiles
by means of pLIF measurements or on a two-dimensional projection of the system and thus do not allow
conclusions about the development of the three dimensional compartments and the exchange rates between
the compartments. 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. The highly resolved particle trajectories further allow detailed Lagrangian analysis of
the mixing dynamics inside the reactor, data that was previously inaccessible.

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. This measurement method allows not only the analysis of the three dimensional flow fields but also
the analysis of the Lagrangian trajectories, and thus, the material transport in the reactor. Fluorescent and

i ii iii

Figure 1: Exemplary representation ( i) front view (1:5), ii) calibration target, iii) top view (1:10) ) of the
stirred tank setup : a) reactor lid, b) bearing box, c) baffle and baffle holder, d) octahedral glycerol basin, e)
stirrer shaft, f) Rushton turbine



buoyancy-neutral particles with a diameter of 150-180 µm are dispersed in the reactor and illuminated with
four customized light sources build in-house using high power LEDs (OSRAM). To track the particles, a
camera setup consisting of four high-speed cameras as well as a recording and synchronization system from
LaVision (Göttingen, Germany) is used. Two identical camera models are installed one above the other at
angles of 30◦, while the two camera pairs are mounted at an angle of 45◦ to each other (see Figure 1 (c)). The
”Shake-The-Box” method is used to determine the Lagrangian tracks, which is currently the most efficient
particle tracking algorithm available (Schanz et al. (2016)). The acquisition of the images as well as the
application of the 4D-PTV algorithms are performed with the commercial DaVis software and the Flow-
Master module from LaVision (Göttingen, Germany). The images are recorded with a spatial resolution of
148 µm/px and a temporal resolution of up to 800 Hz.
In Figure 2 first results are depicted. The instantaneous and time-averaged flow fields for a baffled and an
unbaffled 3L stirred tank reactor (see i) are presented. In the oral presentation a first analysis of the measured
Lagrangian tracks (see Figure 2 ii), but also the mixing dynamics will be discussed.

i ii

Figure 2: i) Time-averaged flow field on a sectional plane through the stirrer shaft. (left: without baffles,
right: with baffles). ii) Selection of 1% of total trajectories in the system (modified velocity magnitude
indicates up- or downwards motion, red: movement upwards; blue: movement downwards).

References
Kuschel M, Fitschen J, Hoffmann M, von Kameke A, Schlüter M, and Wucherpfennig T (2021) Validation

of novel lattice boltzmann large eddy simulations (lb les) for equipment characterization in biopharma.
Processes 9

Rosseburg A, Fitschen J, Wutz J, Wucherpfennig T, and Schlüter M (2018) Hydrodynamic inhomogeneities
in large scale stirred tanks - influence on mixing time. Chemical Engineering Science 188:208 – 220

Schanz D, Gesemann S, and Schroeder A (2016) Shake-the-box: Lagrangian particle tracking at high parti-
cle image densities. Experiments in Fluids volume 70

Taghavi M and Moghaddas J (2020) Flow characteristics of the rushton and pitched blade turbines in turbu-
lent and laminar mixing. International Journal of Chemical Reactor Engineering 18


	Experimental Method and First Results