Preliminary verification, validation and stabilization of Reynolds stress models using the CFD Software by ONERA, DLR, Airbus (CODA)

Kurzfassung

This work presents the preliminary verification and validation of the SSG/LRR-ln$(\omega)$ Reynolds stress model (RSM) in the flow solver CODA. The verification of the implementation and the model validation are described for turbulent boundary layer and airfoil flows. Then the robustness within the implicit numerical solution scheme in CODA and the convergence behaviour are analysed. Different convergence criteria are considered, i.e., convergence of the residual and Cauchy-convergence of surface quantities like C_p and C_f and of integral coefficients. Violation of realizability constraints for the Reynolds stresses is found to cause robustness issues. In the present context of an implicit solution scheme, classical clipping strategies cannot be applied, and hence different alternative methods to ensure realizability are studied. Best robustness improvement is found by non-linear positivity filters, which are used during the transient phase for steady state problem and then deactivated to achieve full residual convergence.