Flow properties of Newtonian and non-Newtonian fluid downstream of stenosis

Blood now behavior around the arteriosclerosis region, which is often recognized as stenosis of the blood vessel, has been paid much attention of late. In this study, the flow properties of Newtonian and non-New-tonian blood analogous fluid are investigated in a straight pipe with sudden construction and expansion, which is a model of arterial stenosis. It is found that introducing pulsation is more effective for the recover of velocity profile downstream of stenosis rather than increasing the Reynolds number in laminar flow range for both fluids. It is distinctive that the velocity profile is not sensitive to Reynolds number for both steady and pulsating flow regimes of non-Newtonian fluid. Since the recovery of velocity profile means momentum transport by convection in the radial direction, mass transport is also expected to be enhanced by pulsation rather than by the increase of Reynolds number. For Newtonian fluid, however, Reynolds number should be higher than for non-Newtonian to achieve sufficient mixing because of the higher sensitivity. Further, it is elucidated by wavelet analysis that the structure of momentum transport is substantially different in spite of the similarity of velocity profile at Reynolds number around 500. This analysis also suggests the superiority of pulsating flow of blood.