4 research outputs found
Red blood cells tracking and cell-free layer formation in a microchannel with hyperbolic contraction: a CFD model validation
Background and Objective: In recent years, progress in microfabrication technologies has attracted the
attention of researchers across disciplines. Microfluidic devices have the potential to be developed into
powerful tools that can elucidate the biophysical behavior of blood flow in microvessels. Such devices
can also be used to separate the suspended physiological fluid from whole in vitro blood, which includes
cells. Therefore, it is essential to acquire a detailed description of the complex interaction between erythrocytes (red blood cells; RBCs) and plasma. RBCs tend to undergo axial migration caused by occurrence
of the Fåhræus-Lindqvist effect. These dynamics result in a cell-free layer (CFL), or a low volume fraction
of cells, near the vessel wall. The aim of the paper is to develop a numerical model capable of reproducing the behavior of multiphase flow in a microchannel obtained under laboratory conditions and to
compare two multiphase modelling techniques Euler-Euler and Euler-Lagrange.
Methods: In this work, we employed a numerical Computational Fluid Dynamics (CFD) model of the
blood flow within microchannels with two hyperbolic contraction shapes. The simulation was used to
reproduce the blood flow behavior in a microchannel under laboratory conditions, where the CFL formation is visible downstream of the hyperbolic contraction. The multiphase numerical model was developed
using Euler-Euler and hybrid Euler-Lagrange approaches. The hybrid CFD simulation of the RBC transport
model was performed using a Discrete Phase Model. Blood was assumed to be a nonhomogeneous mixture of two components: dextran, whose properties are consistent with plasma, and RBCs, at a hematocrit
of 5% (percent by volume of RBCs).
Results: The results show a 5 μm thick CFL in a microchannel with a broader contraction and a 35 μm
thick CFL in a microchannel with a narrower contraction. The RBC volume fraction in the CFL is less
than 2%, compared to 7–8% in the core flow. The results are consistent for both multiphase simulation
techniques used. The simulation results were then validated against the experimentally-measured CFL in
each of the studied microchannel geometries.
Conclusions: Reasonable agreement between experiments and simulations was achieved. A validated
model such as the one tested in this study can expedite the microchannel design process by minimizing
the need to prefabricate prototypes and test them under laboratory conditions.The work was partially supported by the Faculty of Energy and
Environmental Engineering, Silesian University of Technology (SUT)
within Ministry of Education and Science (Poland) statutory research funding scheme (MG, ZO) and by the Silesian University
of Technology rector’s pro-quality grants No. 02/040/RGJ21/1011
(SS) and 08/060/RGJ21/1017 (ZO) and National Center of Science
(Poland) No. 2017/27/B/ST8/01046 (BM). Rui Lima and João M.
Miranda were partially funded by Portuguese national funds of
FCT/MCTES (PIDDAC) through the base funding from the following
research units: UIDB/00532/2020 (Transport Phenomena Research
Center CEFT) and UIDB/04077/2020 (MEtRICs)