{\it A Priori} Assessment of the FDF Sub-Closures in Compressible Turbulence

Results are presented of {\it a priori} assessment of some of the sub-closures required in LES via FDF in compressible turbulent flows. This is done via assessment of DNS of several turbulent flow configurations at varying compressibility levels and Reynolds numbers. Optimum model parameters are calculated by maximizing the correlation coefficients between the SGS exact and modelled terms. The effects of the filter width are also assessed for some of the sub-closures.