numerical investigation of angulation effects in stenosed renal arteries

background: numerical study of angulation effects of renal arteries on blood flow has been of great interest for many researchers. objective: this paper aims at numerically determining the angulation effects of stenosed renal arteries on blood flow velocity and renal mass flow. method: an anatomically realistic model of abdominal aorta and renal arteries is reconstructed from ct-scan images and used to conduct numerical simulation of pulsatile non-newtonian blood flow incorporating fluid-structure interaction. the renal arteries in the realistic model have left and right branch angles of 53° and 45°, respectively. atrapezium shape stenosis is considered in the entrance of right renal artery. two other branch angles, i.e. 90° and 135°, are also considered for right renal artery to study the angulation effects. results: comparison between models with right renal branch angles of 45°, 90° and 135° reveals that high curvature of streamlines in the entrance of the renal artery with the angle of 135˚ causes the flow velocity and renal mass flow to be less than those of 45˚and 90˚. conclusion: it is concluded that large renal branch angles cause the arteries to be unable to deliver blood in the requisite amounts to kidney. kidney responds to counteract low blood flow by activating the renin-angiotension system which leads to severe hypertension.