Red blood cell dynamics in fluid flow using a mesoscopic membrane model and immersed boundary method

Blood is a suspension of different types of cells in plasma, with RBCs constituting the major portion measuring around 45% of the total volume of the blood. When floating freely in plasma, RBCs have a biconcave shape, however they are flexible and easily deform under stress, which gives them ability to squeeze through narrow capillaries where oxygen and carbon dioxide are exchanged with the surrounding tissues. These factors indicate that RBCs have a significant influence on the dynamics of blood flow in the vasculature. Thus, the need of understanding the RBC dynamics, coupled with the challenges associated in-vivo studies, has driven us to develop an in-silico model to accurately simulate the dynamics of the RBCs in the capillary blood flow. A computational technique is developed where the viscoelastic RBC membranes are modelled using a mesoscopic coarse-grained model whereas the blood plasma is modelled with a finite volume Navier-Stokes solver. Immersed Body Method (IBM) is used to model the fluid-RBC interactions. The model is validated by analyzing its ability to describe RBC deformation in optical tweezers stretching tests, shape development in Poiseuille flow, and dynamics in simple shear flow.