Effect of a time-dependent constriction on pulsatile flow of incompressible fluid in a tube

The dynamics of the pulsatile flow field in a tube that has a constriction with a time dependent size is studied. The size and shape of the constriction change in a periodic manner which is nonlinearly related to the periodic changes in the flow. A numerical method is used in order to study the flow field in the vicinity of a time dependent constriction on pulsatile flow in a tube. This analysis is based on a simplified model in which fluid is assumed to be Newtonian, while the flow is laminar and has a simple periodic pulsation. It is farther assumed that the constriction is axially symmetric with a shape that changes periodically in a given way. The presence of the time dependent constriction on the pulsatile flow causes various instabilities to occur. These instabilities and their effects are investigated for a Reynolds number of 200 over a range of dimensionless frequency of 5 less than or equal to a less than or equal to 10 where a is the reduced frequency parameter.