Numerical study on laminar separation of flow over a backward facing step : on the distribution of pressure gradient near the reattachment point

The present paper was concerned with a part of the series of study on the expansion channel flow by authors. The flow over a backward facing step mounted in a two-dimensional channel was investigated numerically, and was especially examined for the relation between recirculating flow zone length and inflow velocity profile. The Navier-Stokes equation and continuity equation (a stream function-vorticity formulation) were solved by the finite difference method (using the pseudo-unsteady technique). The calculation was performed for the range of Reynolds number Re≦500,and for three cases of different inflow velocity profiles at the step of constant step ratio h/H=0.5 (h and H being step height and channel width respectively). A basic data concerning the effect of inflow velocity profile on the reattachment length has already been reported in our previous paper (1988 and 1993). In this report, relation between the pressure gradient on the wall surface and recirculating flow zone was examined near the reattachment point.