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 incoming flow is specified at the upstream boundary and the flow is investigated for several constriction sizes. Large flow structures are developed downstream of the constriction even for very small constriction size. The flow structures consist of several vortices that are created in each cycle and propagate downstream until they are washed away with the acceleration of the incoming flow. Additional vortices are created by a vortex multiplication process. The strength and total number of vortices generated in each cycle increase with the severity of the constriction. The maximal size of the vortices as well as their propagation speed are independent of the constriction size. These findings may be used for devising noninvasive methods for detecting the severity of stenoses in blood vessels and the potential damage to blood elements and thrombus formation caused by vortices.