Comparison between explicit filterings with smooth and cutoff filters in the large eddy simulation of turbulent channel flows

The Large Eddy Simulation (LES) equations are obtained by applying a low-pass filter to the Navier–Stokes equations. The turbulence modeling in the LES method is affected by the shape of the applied filter. In this paper, two explicit filtering methods are compared during the simulation of fully developed turbulent channel flows. First, a fully developed turbulent channel flow is simulated by explicit filtering, using a smooth Laplace filter. In this case, the subfilter stress term is added to the subgrid model. Good agreement is observed between the calculated results and the available direct numerical simulation results. Second, to evaluate the effects of the explicit filter shape as it relates to the cutoff filter, three kinds of filters are used for the flow simulation. Finally, the ability of each approach to predict turbulence statistics is investigated. Moreover, the boundary layer regions that have the highest effect on each approach are specified.