Numerical Simulation of Tank-Treading and Tumbling Motion of Red Blood Cell in the Poiseuille Flow in a Microchannel With and Without Obstacle

Abstract

In the present study, the dynamics of a red blood cell (RBC) in a simple microchannel and in a microchannel with obstacle is simulated using combined lattice Boltzmann-immersed boundary method. The fluid flow field is solved for using LBM and the interaction between the fluid and the RBC is simulated using the IBM. The RBC is considered as a deformable boundary immersed in the fluid flow. When the RBC is stiffer, the flow passage is further blocked due to the lack of flexibility of the RBC causing the flow velocity to decrease and greater drag force (resistance force against the motion of cell) from the fluid to be exerted on it. As a result, the pressure around the RBC increases and becomes even higher than the inlet pressure of microchannel. This increased pressure is thought to be the reason of many serious diseases including cardiovascular diseases. If the number of RBCs used in the simulation increases, the pressure increase would be more appreciable. In addition, the high-flexibility RBC experienced tank-treading motion due to its low elastic and bending coefficients whereas for the low-flexibility RBC the tumbling motion took place. The mechanical properties of RBCs are the determining factor in the distribution of hematocrit in microcirculation. The current results showed good agreement with the available results.