NUMERICAL STUDY OF A BACKWARD-FACING STEP WITH UNIFORM NORMAL MASS BLEED

This study presents the numerical predictions of the fluid flow charac teristics within the recirculation zone for a backward-facing step wit h uniform normal mass bleed. The turbulent governing equations are sol ved by a control-volume-based finite-difference method with power-law scheme. A new turbulence model is proposed to describe the turbulent s tructure. Non-uniform staggered grids are used. The parameters studied include entrance Reynolds number (Re), and the velocity of the normal mass bleed (V-s). The channel expansion ratio ER = 1.3, and the worki ng medium is air. The numerical results show the uniform normal mass b leed suppresses the reverse horizontal velocity, turbulence intensity, and Reynolds shear stress within the recirculation zone. The attachme nt point extends to downstream. Better computational predictions are o btained with the new turbulence model by the introduction of the Kolmo gorov velocity scale, U-epsilon = (nu epsilon)(1/4) instead of frictio n velocity U-tau . Copyright (C) 1996 Elsevier Science Ltd.