FORCES ON AN ADHERING CELL

Summary A basic 2D numerical model has been developed to gain insight into the surface deformations and forces experienced by an adhering, elastic cell in flows with negligible inertial effects. When adhering in unbounded uniform flow, the cell experiences a drag force that increases non-linearly with dimensionless velocity. When adhered to a plane wall in linear shear flow, the cell experiences a drag force that increases linearly, and a lift force that increases non-linearly, with dimensionless shear rate. RESULTS A critical function of certain blood cells is the ability to adhere to vessel walls. The bonds that form between the cell surface and the vessel wall allow the cell to decelerate from the blood flow and stably attach. Recent studies have utilised volume-of-fluid models or rigid models to study cell adhesion [1],[2]. These methods do not provide accurate representations of surface deformation and surface forces. The present study aims to provide some understanding of these properties during cell adhesion, and to determine the effect of the elasticity of the cell membrane. As a first approximation, a blood cell is modelled as a neutrally buoyant, two-dimensional, elastic capsule of Newtonian fluid, suspended in a fluid of identical viscosity. In many blood vessels the inertial forces experienced by cells are very small. In this study the inertial effects are assumed to be negligible, facilitating the use of the boundary integral method. The numerical method used in this study is almost identical to that in [3]. The deformation of an initially circular cell is considered, both in uniform unbounded flow and in bounded linear shear flow. The cell is subjected to sudden flow at t = 0, with one node fixed to represent the formation of a bond. The cell then deforms until a steady state solution is reached