Under consideration for publication in J. Fluid Mech. 1 Shear-Improved Smagorinsky Model for Large-Eddy Simulation of Wall-Bounded Turbulent Flows

A shear-improved Smagorinsky model is introduced based on recent results concerning mean-shear effects in wall-bounded turbulence by Toschi et al. (2000). The Smagorinsky eddy-viscosity is modified as νT = (Cs∆) 2(|S | − |〈S〉|): the magnitude of the mean shear |〈S〉 | is subtracted from the magnitude of the instantaneous resolved rate-of-strain tensor |S|; CS is the standard Smagorinsky constant and ∆ denotes the grid spacing. This subgrid-scale model is tested in large-eddy simulations of plane-channel flows at Reynolds numbers Reτ = 395 and Reτ = 590. First comparisons with the dynamic Smagorinsky model and direct numerical simulations for mean velocity, turbulent kinetic energy and Reynolds stress profiles, are shown to be extremely satisfactory. The proposed model, in addition of being physically sound and consistent with the scale-by-scale energy budget of locally homogeneous shear turbulence, has a low computational cost and possesses a high potentiality of generalization to complex non-homogeneous turbulent flows. 1