Numerical simulation of transient dynamic behavior of healthy and hardened red blood cells in microcapillary flow.

In a number of human diseases such as diabetes mellitus and sickle cell anemia, variations in mechanical properties of red blood cells (RBCs) occur and cause reduced deformability. Investigating the behavior of such abnormal, hardened RBCs in microcapillary flow is of prime importance because of their effects on oxygen transport process. In the present paper, dynamic response of a RBC to a microcapillary flow is numerically studied at steady and transient conditions, considering the effect of essential parameters including RBC deformability, its initial orientation, velocity, and flow pressure gradient. Simulations are performed using a three-dimensional hybrid method, combining lattice Boltzmann method for plasma flow, finite element method for RBC membrane analysis, and immersed boundary method for their interaction. Quantitative and qualitative validations with the experimental data for different RBC velocities verify the accuracy of applied numerical method. Apart from the initial orientation, RBC experiences a complex shape deformation in which the biconcave discoid shape changes to a parachute-like shape. While deformation index of RBC does not change considerably with RBC deformability at steady state condition, it plays an important role in its shape evolution under transient condition. Copyright © 2016 John Wiley & Sons, Ltd.