Influence of spatial discretization schemes on accuracy of explicit LES: Canonical problems to engine-like geometries

Abstract

The choice of the spatial discretization scheme and the subgrid-scale (SGS) model can have a significant impact on the accuracy of Large Eddy Simulations (LES). A systematic study of the influence of the advection term discretization scheme, namely (CDS, LUST) and the SGS model (σ-model, WALE and dynamic Smagorinsky) on the accuracy of the solution is presented in this work. Three canonical cases with increasing complexity are considered in this study, namely, a fully developed turbulent channel flow with Reτ=395, a backward facing step and a wall-mounted hump. Mean errors with respect to DNS or experimental data are quantified in order to compare the relative accuracy of each combination of scheme/model. Detailed comparison of the numerical simulations performed by the open-source CFD code OpenFOAM® shows that the σ-model with the LUST discretization scheme yields the best results. This combination of σ-model with LUST discretization scheme has hence been used to study the turbulent flow characteristics in an engine-like geometry. Results show good agreement with experimental data.