Boundary element analysis of deformation and movement of a capsule and a red blood cell close to the wall

Abstract

A capsule is defined as a liquid drop enclosed by an elastic membrane. The study of capsule behavior near a stationary surface has a number of biological applications, such as red blood cells in the cardiovascular system. However, near-wall behavior of capsules has not been established well. In this study, we investigate the motion of initially spherical and biconcave capsules in simple shear flow near an infinite plane using a boundary integral method coupled to a finite element method. We find that the deformation of a capsule depends on its initial shape, orientation, and capillary number (Ca). However, the lift velocity of a capsule is dependent on its steady state deformation and distance from the wall. The dependence of lift velocity on deformation may help to explain phenomena such as leukocyte margination.