A NUMERICAL ANALYSIS OF THE LATERAL MIGRATION OF FLOWING CELLS
Stephanie Nix1, Yohsuke Imai2, Takuji Ishikawa
1Akita Prefectural University, Japan;
2Tohoku University, Japan
Cells in the blood exhibit varying behavior depending on their mechanical properties. For example, red blood cells, which are quite deformable, are found to flow in the center of blood vessels, leading to the formation of a cell-free layer near the vessel wall. On the other hand, white blood cells, which are much stiffer than red blood cells, and platelets, which are much smaller, are disproportionately found to flow in the region near the wall. As white blood cells and platelets must interact with the vessel wall to perform their intended functions, it is physiologically advantageous for these cells to flow near the wall, but the factors leading to this flow behavior have not been sufficiently clarified. In this study, we investigate the hydrodynamic factors that affect the cell velocity in the direction perpendicular to the flow direction. By neglecting the effect of inertia, which is negligible in the microcirculation, the problem is reduced to a combination of two factors: the curvature of the flow and the presence of a wall. We show how these factors depend on hydrodynamic properties such as the shear rate and the viscosity ratio between the fluids inside and outside the cell, and we describe the relative effects of these factors as a function of the shape of the enclosing container.