Simulation of blood flow in human aorta with emphasis on outlet boundary conditions

Blood flow in human aorta and its major branches is analyzed by computational fluid dynamics, for physiologic and extracorporeal circulation, the latter being the main focus. Mainly, a steady-state analysis is applied corresponding to extracorporeal circulation conditions. For physiologic circulation, pulsatile flow is also investigated. Distensibility of aorta walls is neglected. Blood is modeled as Newtonian fluid. The SST model is employed for turbulence in all cases, for a coherent treatment of the flows exhibiting Reynolds numbers encompassing the transitional regime. For modeling outlet boundary conditions, a simple model based on the prescription of loss coefficients is proposed, which is believed to be more favorable than some more straightforward techniques such as the prescription of an outlet pressure. For physiologic circulation, it is observed that the time-averaged velocity field of pulsatile flow does not show remarkable differences to steady-state results. For extracorporeal circulation, two cases, namely an antegrade and a retrograde perfusion are investigated. Flow patterns observed for the physiologic circulation and the extracorporeal circulation techniques show considerable differences. For extracorporeal circulation, much larger wall shear stress values are predicted. This indicates that mobilization of arteriosclerotic plaques needs to be considered as a very important issue for the extracorporeal circulation.