COMPUTATION OF BACKWARD-FACING STEP FLOWS BY A 2ND-ORDER REYNOLDS STRESS CLOSURE-MODEL

This paper scrutinizes the predictive ability of the differential stre ss equation model in complex shear flows. Two backward-facing step flo ws with different expansion ratios are solved by the LRR turbulence mo del with an anisotropic dissipation model and the near-wall regions of the separated side reserved by a near-wall model. The computer code d eveloped for solving the transport equations is based on the finite-vo lume-finite-difference method. In the numerical solution of the time-a veraged memenum equations the Reynolds stresses are treated partially as a diffusion term and partially as a source term to avoid numerical instability. Computational results are compared with experimental data . It is found that the near-wall region of the separated side resolved by the near-wall model, the LRR model with a simple modification of a n anisotropic dissipation model can predict backward step flows well.