On the Spectral Eddy Viscosity in Isotropic Turbulence

The spectral eddy viscosity model is investigated through the large eddy simulation of the decaying and forced isotropic turbulence. It is shown that the widely accepted 'plateau and cusp' model overpredicts resolved kinetic energy due to the amplification of energy at intermediate wavenumbers. Whereas, the simple plateau model reproduces a correct energy spectrum. This result overshadows a priori tests based on the filtered DNS or experimental data. An alternative method for the validation of subgrid-scale model is discussed.