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PHYSICAL INSIGHT INTO THE UNSTEADY SHOCK-WAVE TURBULENT BOUNDARY LAYER INTERACTION USING LARGE EDDY SIMULATION

G. Aubard
DynFluid Laboratory Arts et Métiers ParisTech 151, boulevard de l'Hopital, 75013 Paris, France

Jean-Christophe Robinet
ENSAM/PARIS SINUMEF Laboratory, 151, Boulevard de I'Hopital 75013 PARIS, France

Xavier Gloerfelt
SINUMEF Laboratory Arts et Metiers ParisTech 151, boulevard de I'Hopital, 75013 Paris, France

Аннотация

Separated flows, characterized by the presence of a recirculation bubble and a shear-layer developping along the bubble, are often the seat of self-sustained low-frequency (LF) dynamics. The case of the shock-wave turbulent boundary layer interaction (SWTBLI) on a flat plate is analysed by means of LES simulations. A recent non-linear modal analysis, based on the 'dynamic mode decomposition' (DMD) is applied to an LES database. The typical LF modes are associated with a cyclic contraction and expansion of the recirculation bubble, taking the form of filling and emptying very close to the description of the mass-budget-based model proposed by Piponniau et al. (2009). The bubble is found to be divided into two zones, an upstream one associated with LF dynamics, and a downstream one associated with high-frequency 'Kelvin- Helmholtz-type' ('KH-type') vortices. When increasing the Strouhal number, the spatial support of the DMD modes moves continuously from the first part of the bubble to the entire bubble and the downstream flow.