Flow Studies in True-to-Scale Models of Human Renal Arteries

Abstract

The flow behavior in rigid and elastic models of human renal arteries have been studied using glycerol-water and a blood-like viscoelastic fluid. The studies were done at steady and pulsatile flow. The differences between Newtonian and non-Newtonian blood-like fluids were especially visible at unsteady flow in the flow separation zones. Here the flow consists of high local convective parts. The studies were limited to the abdominal aorta downstream of the renal arteries where most sclerotic plaques are formed. The flow was visualized by using dyes and a birefringent solution. The disturbed flow can easily be localized with these methods. The velocity profiles were measured with a laser-Doppler-anemometer. The velocity gradients increased in the pulsatile flow between the main forward and reverse flow. These lead to higher shear stresses which can activate blood platelets and change the surface of the membrane of red cells. We found about a 15% flow increase during pulsatile flow with a representative Reynolds number of 250 for the Polyacrylamide mixture compared to glycerol-water.