PULSATILE ALBUMIN TRANSPORT IN LARGE ARTERIES - A NUMERICAL-SIMULATION STUDY

Albumin transport in a stenosed artery configuration is analyzed numer ically under steady and pulsatile flow conditions. The flow dynamics i s described applying the incompressible Navier-Stokes equations for Ne wtonian fluids, the mass transport is modelled using the convection di ffusion equation. The boundary conditions describing the solute wall f lux take into account the concept of endothelial resistance to albumin flux by means of a shear dependent permeability model based on experi mental data. The study concentrates on the influence of steady and pul satile flow patterns and of regional variations in vascular geometry o n the solute wall flux and on the ratio of endothelial resistance to c oncentration boundary layer resistance. The numerical solution of the Navier-Stokes equations and of the transport equation applies the fini te element method where stability of the convection dominated transpor t process is achieved by using an upwind procedure and a special subel ement technique. Numerical simulations are carried out for albumin tra nsport iii a stenosed artery segment with 75 percent area reduction re presenting a late stage in the progression of an atherosclerotic disea se. It is shown that albumin wall flux varies significantly along the arterial section, is strongly dependent upon the different flow regime s and varies considerably during a cardiac cycle. The comparison of st eady results and pulsatile results shows differences rep to 30 percent between time-averaged flux and steady flux in the separated flow regi on downstream the stenosis.