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

摘要

This paper scrutinizes the predictive ability of the differential stress equation model in complex shear flows. Two backward-facing step llows with different expansion ratios are solved by the LRR turbulence model with an anisotropic dissipation model ami the near-wall region of the separated side resolved by a near-wall model. The computer code developed for solving the transport equations is based on the finite-volume-finite-difference method. In the numerical solution of the time-averaged momeiium 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 an anisotropic dissipation model can predict backward step flows well.