INFLUENCE OF NON-NEWTONIAN BEHAVIOR OF BLOOD ON FLOW IN AN ELASTIC ARTERY MODEL

Two different non-Newtonian models for blood, one a simple power law m odel exhibiting shear thinning viscosity, and another a generalized Ma xwell model displaying both shear thinning viscosity and oscillatory f low viscoelasticity, were used along with a Newtonian model to simulat e sinusoidal flow of blood in rigid and elastic straight arteries. Whe n the spring elements were removed from the viscoelastic model resulti ng in a purely viscous shear thinning fluid the predictions of flow ra te and WSS were virtually unaltered Hence, elasticity of blood does no t appear to influence its flow behavior under physiological conditions in large arteries, and a purely viscous shear thinning model should b e quite realistic for simulating blood flow under these conditions. Wh en a power law model with a high shear rate Newtonian cutoff was used for sinusoidal flow simulation in elastic arteries, the mean and ampli tude of the flow rate were found to be lower for a power law fluid com pared to a Newtonian fluid experiencing the same pressure gradient. Th e wall shear stress was found to be relatively insensitive to fluid rh eology but strongly dependent on vessel wall motion for flows driven b y the same pressure gradient. The effect of wall motion on wall shear stress could be greatly reduced by matching flow rate rather than pres sure gradient. For physiological flow simulation in the aorta, an incr ease in mean WSS but a reduction in peak WSS were observed for the pow er law model compared to a Newtonian fluid model for a matched flow ra te waveform.