MODELLING OF COMPRESSIBILITY EFFECTS IN MIXING LAYER
The ability of turbulence models to predict self-similar mixing layers is investigated. The influence of velocity ratio is well captured but no model reproduces the sensitivity of the mixing layer to density differences. A correction proposed for boundary layer flows hardly affects mixing layer predictions. A correction accounting for baroclinic effect is derived but is not satisfactory. At last, compressible turbulence effects are investigated. Without corrections, models cannot predict the spreading rate reduction. Standard corrections, based upon dilatational terms, predict too weak a reduction. The sonic eddy concept is validated whatever the turbulence model. A form suitable for Navier-Stokes codes is proposed.
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