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

PIV measurement of complex flow characteristics in
open-cell metal foam replica

Minsin Kim1, Youngwoo Kim1, Sajjad Hosseini1, Kyung Chun Kim1∗

1 Pusan National University, School of Mechanical Engineering, Busan, South Korea
∗ kckim@pusan.ac.kr

Abstract
Time-resolved 2-D particle image velocimetry was used to study on turbulent flow characteristics inside an
open-cell metal foam under the laminar and turbulent inlet conditions. A study on the effect of Reynolds
number was conducted with different three channel Reynolds numbers, 1000, 5000 and 10000. 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. It is confirmed that there is a similarity
of the preferred flow path flows take regardless of Reynolds number.

1 Introduction
Metal foam is a metallic sponge which consists of many ligaments and nodes interconnect the struts. Metal
foam structures have been of interest because their geometrical characteristics like high porosity, large spe-
cific surface area. Due to the great potential of applications, various studies have been conducted to under-
stand the flow inside metal foam. However, flow characteristics inside metal foam are not fully understood
because highly complex geometry of metal foam makes us difficult to observe flow inside metal foam. The
characteristics of metal foam internal flow with a laminar flow inlet condition were studied by Moon et al.
(2018). In the present study, however, particle image velocimetry (PIV) measurement was conducted to ob-
serve the turbulent characteristics of inside metal foam in detail when turbulent flow or laminar flow enters
the metal foam replica.

Figure 1: Experimental setup

Figure 2: Contours of mean velocity magnitude of 6 view (a) Re = 10,000 (b) Re = 5,000 (c) Re = 1,000



Figure 3: Contours of root-mean-squared temporal fluctuation velocities of streamwise component (upper
row) and transverse component (lower row) (a),(d) Re = 10,000 (b),(e) Re = 5,000 (c),(f) Re = 1,000

2 Method
The size of the replica is 80 mm × 80 mm × 200 mm and the cell diameter, pore diameter, strut diameter,
and porosity of the replica are 36.08 ± 4.24 mm, 15.6 ± 1.32 mm, 3.2 ± 0.24 mm, and 0.92, respectively.
The transparent metal foam model was placed inside a vertical water channel with same dimension. The
experimental loop containing the test section is shown in Fig. 1.

3 Results and Discussion
Fig. 2 shows the velocity magnitude fields. Refractive index of metal foam and fluid could not be matched,
however, it was possible to observe the flow in part due to the large size of the pore. It is found that there
is similarity in the flow path regardless of Reynolds number. This indicates that the preferred path the fluid
takes through the metal foam structure is not different in the different flow regimes. This is similar result
from Lu et al. (2020). Fig. 3 shows contours of the fluctuation velocities. When a turbulent flow with a
turbulence intensity of 10% enters the metal foam, the turbulent intensity increases while passing through
the metal foam replica. In the case of laminar inlet condition, the value of u

′

rms/Ub of the upstream are near
zero, but they increase to 0.1-1.4 inside the metal foam structure. This indicates there are flow disturbances
induced by metal foam structure even at a laminar inlet condition. After passing through the metal foam
structure, turbulent decays due to the shear-free uniform flow and all the enhanced turbulence recover to
initial state.

4 Conclusions
Further discussion about the turbulent characteristics such as vorticity and turbulent kinetic energy inside
metal foam will be provided at the conference.

Acknowledgements
This work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea
government(MSIT) (No. 2020R1A5A8018822).

References
Lu X, Zhao Y, and Dennis DJ (2020) Fluid flow characterisation in randomly packed microscale porous

beds with different sphere sizes using micro-particle image velocimetry. Experimental Thermal and Fluid
Science 118:110136

Moon C, Kim HD, and Kim KC (2018) Kelvin-cell-based metal foam heat exchanger with elliptical struts
for low energy consumption. Applied Thermal Engineering 144:540–550


	Introduction
	Method
	Results and Discussion
	Conclusions