NON-NEWTONIAN PULSATILE FLOW IN AN ABDOMINAL AORTA − RENAL ARTERY JUNCTION
The effects of non-Newtonian behavior and pulsatility of blood flow on the spatio-temporal distribution of hemodynamic indicators relevant for atherosclerosis are investigated using a rheologically accurate shear-thinning Yeleswarapu model for blood. The propensity of atherosclerosis plaque formation is identified using the CFD predictions of appropriate hemodynamic indicators-low AWSS, High OSI and High RRT. These show that, in the human abdominal aorta-renal artery junction, the upper surface regions of the renal artery downstream of the entrance are most prone to atherosclerosis. We numerically compared flow predictions for the validated shear thinning Yeleswarapu model and Newtonian model under the steady flow conditions (Re = 1000) in a basic 3D geometry whose dimensions are similar to those of human abdominal aorta-renal artery junctions. The result show that the Yeleswarapu model would predict the WSS higher compared to the Newtonian case. Hence, applying an accurate rheological model for blood is crucial to capture the hemodynamic effects, and this has been satisfied by the Yeleswarapu model. The effects of pulsatile flow (ƒ = 1.25 Hz and Re = 1000) on hemodynamic indicators are studied as pulsatility is considered an important atherogenic factor. High OSI and low AWSS develop in the regions of renal artery. Low AWSS (<0.5 Pa) are considered atherogenic, and this can be seen at the top surface of the renal artery. OSI and AWSS are not sufficient parameters as it is not always necessary for them to overlap. RRT describes the residence time of particles. High RRT (>15) is found to coincide with the low AWSS and high OSI on the upper surface of the renal artery downstream of the entrance, indicating that this area is prone to atherosclerosis.