Multiscale, Cell-Resolved Simulations of Red Blood Cells in Macroscale Flows with Cell-Cell Interactions

Hemolysis, or the rupture of red blood cells (RBCs), is a common issue in many blood flow problems, particularly in implanted medical devices, which often expose the RBCs to non-physically large shear stresses. While hemolysis is often estimated using empirical methods that are not generalizable to arbitrary flows, if the behavior of the actual RBCs can be accurately resolved, the results should be suitable for any flow or geometry. The purpose of this work is to construct a computational framework for accurately resolving the response of RBCs in macroscale flows. The large difference in scale between the RBCs and the macroscale flows makes direct simulations computationally infeasible; however, it is assumed that the effects of the RBCs can be modeled in the macroscale flow, for example by using a shear-thinning viscosity, leaving only the effect of the flow on the RBC. The RBCs are advected through the flow as Lagrangian tracers. At each time step, the velocity field around the cell, along with its current deformation, is used as in input into a boundary integral solver to obtain the cell's velocity. Additionally, cell-cell interactions, constituting an essential component of the motion of the cells, are especially difficult to resolve, and potential solutions are discussed.