Performance of Subgrid Flamelet Model in LES of Reacting, Turbulent Flows
AEROSPACE RESEARCH CORP STONY BROOK NY
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Large eddy simulation LES with a flamelet-based chemistry model has been evaluated through a priori and a posteriori tests in both decaying homogeneous turbulence and spatially developing mixing layers. The present fiamelet-LES approach involves a series of models, among which are the models for the PDF of mixture-fraction fz and the conditional filtered dissipation rate Chist. We test three models for fz a delta-PDF fz deltaz b beta-PDF, c Gaussian PDF and two models for Chist. The Gaussian PDF model consistently performs almost as well as the beta-PDF, and may provide an alternative approach to the beta-PDF method. This point is important to the LES simulations since the calculation of Gaussian function is much cheaper than that of beta-function. Eurthermore, it may be said from the error analyses that the counterflow model for Chist has average performance in its present form and that a phenomenological model in the form of Eq. 6 exists with an optimum value of a parameter C3 to produce a better result. The a posteriori analysis shows a satisfactory performance of the fiamelet model within the context presented in this paper.
- Fluid Mechanics