Removal of the highest energy POD mode for optimal construction of subgrid-scale parameters in a SPIV-measured turbulent mixing layer flow

Abstract

Large eddy simulation is based on decomposition of turbulent flow structures to large energy-containing scales and small subgrid-scale (SGS) structures. The present study analyzes the effect of removing high-energy modes of flow to find the optimal construction of SGS parameters using the a priori approach. The data belong to a shear layer flow measured by stereoscopic particle image velocimetry (SPIV). The proper orthogonal decomposition (POD) method is used to capture all energy modes of the acquired velocity field. The missing/erroneous data are reconstructed using the gappy POD method. Particularly, similarity and mixed models are used to evaluate the SGS parameters. The results of the mixed model are compared via the a priori approach, before and after removing the high-energy modes. For the present flow, it is found that removal of just the first POD mode (as a representative of the mean flow) leads to the best SGS reconstruction, and this results in one order of magnitude higher precision of the average SGS stresses.