On the Role of Low Energy Modes of the Flow on Sub-Grid Scale Parameter Prediction

Abstract: Large Eddy Simulation is based on decomposition of turbulent flow structures to large energy containing scales and small subgrid scales. The present study captures all flow low energy modes of a sample shear layer using the proper orthogonal decomposition (POD) method. In order to analyze the role of flow low energy modes on subgrid scale parameter prediction, the a-priori approach is chosen on a stereoscopic particle image velocimetry (SPIV) data that its missing/erroneous data is 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, before and after removing the high energy modes. It is shown that SGS stress is predicted more accurately in the mixed model after removing the highest energy mode.