Computational Approach

The MEGAFLOW development includes two different Finite-Volume flow solvers, viz. the block-structured FLOWer and and the unstructured TAU code, both mainly devised at DLR. They will be introduced in brief here, however, only the features relevant for this work will be given. FLOWer is is a density-based solver with different metric schemes on block-structured grids. For the purpose of the work reported, a cell-vertex scheme is used. Spatial discretization is based on central differences with added artificial dissipation, an explicit Runge-Kutta scheme being employed to integrate in time. The code is second-order accurate in space and time and uses multigrid acceleration in conjunction with a multiblock formulation. TAU has very similar features, however, as the solver is unstructured, a dual-mesh approach is used, rendering the solver independent of the element type used in the primary mesh. Both solvers run on various computer systems, including vector and massively parallel architectures.

In the framework of the MEGAFLOW project, six different linear models were implemented and validated in FLOWer at TU Berlin, viz. LLR $k$-$\omega$, Menter SST $k$-$\omega$, LEA $k$-$\omega$, L-EARSM + Wilcox $k$-$\omega$, SA and SALSA. All models were integrated in conjunction with low-Reynolds boundary conditions. More recently, under the umbrella of the ongoing EU $5^{th}$ Framework Programme TAURUS, the two non-linear EASM, viz. RQEVM + Wilcox $k$-$\omega$ and EARSM + Kok $k$-$\omega$, were implemented in the TAU solver. This work is included here, as it forms a natural continuation of the MEGAFLOW efforts.