A new form of the elliptic relaxation equation to account for wall effectsin RANS modeling

Different methods for improving the behavior in the logarithmic layer of th e elliptic relaxation equation, which enable the extension of Reynolds stre ss models or eddy viscosity models down to the wall, are tested in a channe l flow at Re-tau=590 and compared with direct numerical simulation (DNS) da ta. First, a priori tests are performed in order to confirm the improvement predicted by the theory, either with the Rotta+IP (isotropization of produ ction) model or the Speziale-Sarkar-Gatski (SSG) model as the source term o f the elliptic relaxation equation. The best form of the model is then used for full simulations, in Durbin second moment closure or in the frame of t he <(v(2))over bar>-f model. It is shown that the results can be significan tly improved, in particular by using a formulation based on the refinement of the modeling of the two-point correlations involved in the redistributio n term. (C) 2000 American Institute of Physics. [S1070-6631(00)50709-0].