Index of Quality for Large Eddy Simulations

In the light of rapidly increasing applications of large-eddy-simulations (LES) it is deemed necessary to impose some quality assessment measures for such studies. The validation of LES is difficult because of the fact that both the sub-grid scale (sgs) model contribution and numerical discretization errors are functions of the grid resolution. In this study various index of quality measures, here and after referred to as LES_IQ, are proposed and applied to some case studies. The recommended LES_IQ is based on the concept of Richardson’s extrapolation. It is postulated that in practical applications of LES numerical dissipation will always be a significant part of the overall dissipation and it must be accounted for in any assessment of the quality of LES results. It is further suggested that an LES_IQ of 75% to 85% can be considered adequate for most engineering applications that typically occur at high Reynolds numbers; LES-IQ greater than 90% can be classified as DNS.