SIMULATION OF THE KOLMOGOROV INERTIAL SUBRANGE USING AN IMPROVED SUBGRID MODEL

A subgrid model is developed and applied to a large-eddy simulation of the Kolmogorov inertial subrange. Currently popular subgrid models are derived from models of the turbulent energy equation, resulting in a significant loss of information as a consequence of the statistical averaging performed in going from the Navier-Stokes equation to the energy equation. The subgrid model developed here is based directly on a model of the Navier-Stokes equation. The improved subgrid model contains two terms: an eddy viscosity and a stochastic force. These terms are computed from the EDQNM stochastic model representation of the momentum equation, and from a fully resolved direct numerical simulation. Use of the subgrid model in a forced large-eddy simulation results in an energy spectrum that exhibits a clear k-5/3 power-law subrange with an approximate value Ko = 2.1 of the Kolmogorov constant.