Computation of backward‐facing step flows by a second‐order Reynolds stress closure model

Abstract

AbstractThis paper scrutinizes the predictive ability of the differential stress equation model in complex shear flows. Two backward‐facing step flows with different expansion ratios are solved by the LRR turbulence model with an anisotropic dissipation model and the near‐wall regions 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 momenum 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.