A self-adapting turbulence model for flow simulation at any mesh resolution

A two-equation transport model is used to model turbulence at any mesh resolution, from Reynolds-averaged Navier-Stokes (RANS), to large eddy simulations (LES), to direct numerical simulations. The two-equation model used is a slight modification of the standard k/epsilon model that allows the backscatter of energy to resolved scales. A mathematical explanation is provided for why RANS models (such as this two-equation model) are applicable to LES. The model automatically adapts to the mesh resolution provided and no interaction from the user is necessary. This approach is tested on the problem of moderately high Reynolds number isotropic decaying turbulence and gives good predictions at any mesh resolution and with different initial conditions. A detailed analysis shows that at LES resolutions the solution remains fully unsteady and three-dimensional and does not approach a RANS-like solution. (c) 2007 American Institute of Physics. (c) 2007 American Institute of Physics.