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Using experimental data from a study of flow over a wall-mounted square cylinder (h=4d) as a baseline, three Reynolds-Averaged Navier-Stokes turbulence models are used in a commercial CFD code Star-CCM+ to compare the relative accuracy of the tested models. In virtually every standard of comparison applied in this study, the Realizable κ−ε with a two-layer treatment proved to be far superior to both the κ−ε V2F (All y+ hybrid wall treatment) and the κ−ω models.
To observe mesh dependence for each of the models, all three were run on three different polyhedral mesh cases. Resulting first prism-layer heights of y+≈12, y+≈5, and y+≈1 allowed comparison of results with the mesh resolved to the buffer layer, the buffer layer/viscous sublayer transformation, and into the viscous sublayer, respectively. In all cases, the Realizable κ−ε proved superior.
The mesh study also suggests that applying the two-layer treatment to Realizable κ−ε allows it to operate well into the viscous sublayer, an area in which κ−ε models are traditionally expected to suffer degradation in accuracy. The κ−ω scheme, however, does not show improvements with increased mesh quality. In contradiction to the expected results, mesh independence is reached by y+≈5 for κ−ω in this study.