Investigation of high-order methods in large-eddy simulation of separated flow in a channel with periodic constrictions

Abstract

In large-eddy simulations (LES), only the dynamics of large scales is computed and the effect of smaller scales is modelled. Scale separation is however difficult to establish since the low-pass filtering arises from a complex combination of implicit filtering by the grid and the discretization schemes. Evenwhen explicit filtering is performed, the implicit filtering due to the application of discretizationmethods changes the shape of the filter function. The principal objective of the current study is to identify the sensitivity of the predictive accuracy to resolution and modelling issues. Simulations were performed for six different finite-difference schemes, six explicit filters and five subgrid-scalemodels on a coarse grid. It is shown in particular that the dissipative part of the discretization scheme plays a determinant role and overwhelms the choice of a SGS closure.