Synthesis of test cases TC-2C and TC-2D - Twodimensional incompressible flows past wall-mounted obstacles

A summary and evaluation is given of the computational predictions made by 3 independent teams using a total of 4 different two-equation models and 3 different Reynolds stress models. The results, in terms of mean velocity, turbulent kinetic energy, Reynolds stress and coefficient of skin friction, are compared mutually and to available experimental results obtained by laser Doppler anemometry. Differences in results obtained with the same turbulence model are ascribed to differences in implementation and meshes, while differences between models clearly reveal strengths and deficiencies of models. Results on skin friction, in particular, show surprisingly large differences for the different models. The standard k,epsilon-model with wall functions performs better than the low-Re k,epsilon-model throughout the recirculation region. In general, Reynolds stress models, particularly those for low-Re number, are superior to two-equation models, but all models underpredict the turbulence level in the shear layer over and downstream of the recirculation region. The new q,zeta-model performs roughly as the low-Re k,epsilon-model, which it replaces, but it has an improved computational efficiency.