THE EFFECT OF CONSTRICTION SIZE ON THE PULSATILE FLOW IN A CHANNEL

The effect of the constriction size on the pulsatile flow in a channel is studied by solving the time-dependent incompressible Navier-Stokes equations. A pulsating in coming flow is specified at the upstream bo undary and the flow is investigated for several constriction sizes. La rge flow structures are developed downstream of the constriction even for very small constriction size. The flow structures consist of sever al vor tices that are created in each cycle and propagate downstream u ntil they are washed away with the acceleration of the incoming flow. Additional vortices are created by a vortex multiplication process. Th e strength and total number of vortices generated in each cycle increa se with the severity of the constriction. The maximal size of the vort ices as well as their propagation speed are independent of the constri ction size. These findings may be used for devising noninvasive method s for detecting the severity of stenoses in blood vessels and the pote ntial damage to blood elements and thrombus formation caused by vortic es.