TERM-BY-TERM TESTS OF STRESS-TRANSPORT TURBULENCE MODELS IN A 3-DIMENSIONAL BOUNDARY-LAYER

Current Reynolds-averaged turbulence models for use in three-dimension al flows have mostly been derived by straightforward generalization of two-dimensional models; the results are rather unsatisfactory. Reynol ds-stress transport methods perform better than methods based on an (i sotropic) eddy viscosity. One approach to the problem is a term-by-ter m check of Reynolds-stress transport models against experiments or sim ulation data in representative three-dimensional flows. In this paper a comparison of four models for the turbulent-transport ''diffusion'' terms, and four models for the pressure-strain ''redistribution'' term s, with measurements (including all six Reynolds stresses and all ten triple products) in the thin boundary layer on the flat floor of a duc t with a 30-degrees bend in the horizontal plane is presented. The con clusion is that the pressure-strain models perform remarkably well, an d that although the triple-product models often perform badly, they re present rather small terms and therefore do not cause large errors in Reynolds-stress predictions. The implication is that inadequate modeli ng of the dissipation must be the main cause of errors in predictions of three-dimensional boundary layers.