Numerical study of the impact of non-Newtonian blood behavior on flow over a two-dimensional backward facing step.
Endothelial cell (EC) responsiveness to shear stress is essential for vasoregulation and plays a role in atherogenesis. Although blood is a non-Newtonian fluid, EC flow studies in vitro are typically performed using Newtonian fluids. The goal of the present study was to determine the impact of non-Newtonian behavior on the flow field within a model flow chamber capable of producing flow disturbance and whose dimensions permit Reynolds and Womersley numbers comparable to those present in vivo. We performed two-dimensional computational fluid dynamic simulations of steady and pulsatile laminar flow of Newtonian and non-Newtonian fluids over a backward facing step. In the non-Newtonian simulations, the fluid was modeled as a shear-thinning Carreau fluid. Steady flow results demonstrate that for Re in the range 50-400, the flow recirculation zone downstream of the step is 22-63% larger for the Newtonian fluid than for the non-Newtonian fluid, while spatial gradients of shear stress are larger for the non-Newtonian fluid. In pulsatile flow, the temporal gradients of shear stress within the flow recirculation zone are significantly larger for the Newtonian fluid than for the non-Newtonian fluid. These findings raise the possibility that in regions of flow disturbance, EC mechanotransduction pathways stimulated by Newtonian and non-Newtonian fluids may be different.
Choi
Hyo Won
HW
Department of Mechanical and Aeronautical Engineering, University of California, Davis, CA 95616, USA.
Barakat
Abdul I
AI
D050197:Atherosclerosis / Q000097:blood / Q000503:physiopathology; D003198:Computer Simulation; D042783:Endothelial Cells / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000378:metabolism*; D018056:Hemorheology; D006801:Humans; D040542:Mechanotransduction, Cellular; D008955:Models, Cardiovascular; D011673:Pulsatile Flow; D013314:Stress, Mechanical