Unsteady laminar separated flow through constricted channel

Abstract

In the present paper unsteady Navier–Stokes equations have been solved numerically by finite-difference technique in staggered grid distribution for a flow through a channel with locally symmetric and asymmetric constrictions. A coordinate stretching has been made to map the infinite irregular geometry into a finite regular computational domain. Pressure and pressure–velocity corrections scheme have been developed. Convergence criteria (in terms of continuity equation) has been achieved after few time iterations. The critical Reynolds number for asymmetric flow through a symmetric constriction has been found. Critical values depend on the area reduction and the length of the constriction. The increment of Reynolds number grows the asymmetry of the flow. The root mean square (r.m.s.) centreline vertical velocity for asymmetric flow through a symmetric constriction has been drawn at different Reynolds numbers. For flow through symmetric constriction the centreline vertical velocity shows finite oscillation behind the constriction at high Reynolds number.