Reynolds-Stress Model Prediction of 3-D Duct Flows

The paper examines the impact of different modelling choices in second-moment closures by assessing model performance in predicting 3-D duct flows. The test-cases (developing flow in a square duct (Gessner and Emery, ASME J. Fluids Eng. 103, 445–455, 1981), circular-to-rectangular transition-duct (Davis and Gessner, AIAA J. 30, 367–375, 1992), and s-duct with large separation (Wellborn et al., J. Prop. Power 10, 668–675 1994) include progressively more complex strains. Comparison of experimental data with selected 7-equation models (6 Reynolds-stress-transport and 1 scale-determining equations), which differ in the closure of the velocity/pressure-gradient tensor πij, suggests that rapid redistribution controls separation and secondary-flow prediction, whereas, inclusion of pressure-diffusion modelling improves reattachment and relaxation behaviour.