Subgrid models for large eddy simulation: Scalar flux, scalar dissipation and energy dissipation

This project can be regarded as a continuation of the research done at the Engine Research Center in the fields of Large Eddy Simulation (LES) and Direct Numerical Simulation model development, evaluation and implementation.; New LES models were proposed for (1) subgrid-scale scalar transport; (2) subgrid-scale dissipation of a scalar; (3) subgrid-scale energy dissipation.; The new models belong to the class of Dynamic Structure (DS) models. The DS models rely on the Leonard-type term to provide the structure of the modeled quantity, and then a particular scaling factor is used. The models were evaluated a priori using DNS databases created at the Engine Research Center for channel flow, Couette flow, non-reacting mixing layer and decaying isotropic turbulence with passive scalar.; A DNS code that was used for creating the DNS databases was modified in order to support Large Eddy Simulation techniques for the purpose of a posteriori evaluation of the most successful among the models proposed. The results from LES and DNS runs were compared for the non-reacting spatially developing shear layer and decaying isotropic turbulence. A good agreement between LES and DNS was observed.; Overall, the new models have been found to perform adequately. In a priori tests the DS models perform as good as the popular models from the literature or better. The thorough a posteriori evaluation of the full suit of models is not yet complete but the available results already indicate a good potential.