A New Approach to Validate Subgrid Models in Complex High Reynolds Number Flows

Abstract

Abstract : This second semi-annual report summarizes the progress made in the last six months. The overall objectives of this research are to develop new methods to evaluate subgrid models and then to utilize these methods to improve the chosen subgrid models. The subgrid models investigated in this research are chosen primarily for application in high Reynolds number complex flows. Preliminary studies of these models have been completed. A priori analysis using data from direct numerical simulations (DNS) homogeneous isotropic flows was carried out, and then the models were implemented in large-eddy simulation (LES) codes and further evaluated. Two types of analysis methods have been developed so far. The first method uses information in Fourier (spectral) space and evaluates the interscale energy transfer as a function of the wavenumbers resolved in the LES. The second, uses information in the physical space and uses cross correlation analysis to investigate the behavior of subgrid models. The physical space analysis method will be the primary analysis tool for the next year's study, since the next phase of research will focus on complex flows such as flows past rearward facing steps and swirling flows.