Explicit vs. implicit subgrid-scale modelling for les

Abstract eng:
This study compares explicit and implicit subgrid-scale modelling for large eddy simulation. The implicit modelling is based on a targeted numerical dissipation introduced by the discretization of the viscous term. The flexibility of the method ensures high-order accuracy while controlling the level and spectral features of the resulting numerical viscosity. A spectral closure can be used to scale it a priori. This relaxation strategy is found more efficient and accurate than the extremely popular Smagorinsky model in standard as well as in dynamic version. Its main advantage is the ability to regularise the solution at the mesh scale, a property that cannot be reached with any of the two versions of the Smagorinsky model that show a strong sensitivity to numerical errors. Despite its purely numerical nature, the present approach can also be viewed as explicit subgrid-scale modelling because of the equivalence with spectral viscosity prescribed on a physical basis.

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