A seamless hybrid RANS/LES model with Dynamic Reynolds-Stress Correction for high Reynolds number flows on coarse grids

To enable economic hybrid RANS/LES of wall-bounded flows at very high Reynolds numbers, two separate RANS and LES velocity and temperature fields are computed in parallel and are dynamically coupled. Both simulations are performed on proprietary grids, each with an optimal, model-adapted topology: a quasi-homogeneous grid for the LES, and a wall-refined high aspect-ratio grid for the RANS simulation. The model automatically governs the blending of RANS and LES stresses on the subgrid-scale level. First, a blending function, based on comparing LES grid quality with integral length scale, automatically determines the mutual correction of RANS and LES solutions. Then, the additional near-wall Reynolds stress correction improves the RANS/LES transitioning behaviour in the viscous and buffer layer. The proposed model ensures consistency, frame invariance and shall increase numerical stability. Overall, this method incorporates ideas from three strands of hybrid modelling, covers heat transfer modelling, also works with second moment closures, is applicable to unstructured grids, requires little user input, and can also be used in an embedded LES mode with even coarser LES grids as outside the local zooming down region only the RANS model drives all the fields.