The shear stress of flowing blood on artery walls and the surfaces of prosthetic devices has a significant influence on the integrity of blood components, the coagulation of blood and formation of thrombi, the production of biochemicals by endothelial cells, the permeability of artery walls to macromolecules and the hydraulic resistance of artery walls to transmural water flux. Our knowledge of wall shear stress magnitudes and spatial variations in the circulation comes primarily from in vitro experiments in rigid models of arterial segments employing Newtonian blood analog fluids. Wall shear stresses have usually been estimated from velocity profile measurements in the near wall region, a method of questionable accuracy which cannot be employed with elastic models or in vivo. In the proposed research we will: 1. Further develop the technique of flush mounted hot film anemometry for application in pulsatile flows with reversal of wall shear stress direction. The proposed technique is based on a pulsed mode of anemometer bridge operation. 2. Determine experimentally the effect of elastic walls and non-Newtonian rheology on the spatial and temporal distribution of wall shear stress in pulsatile flows through curved artery models. We will measure wall shear stresses by flush mounted hot film anemometry techniques in pulsatile flows through both rigid and elastic curved artery models with glycerol/water and Separan/water solutions as well as blood. 3. Determine through numerical simulations the effect of elastic walls and non-Newtonian rheology on the fluid mechanics of pulsatile flows through curved artery models. We will first extend our rigid tube, Newtonian fluid simulations to include elastic walls. Ultimately we will include non-Newtonian rheology.
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