DOI: 10.1615/TSFP7
PHYSICAL INSIGHT INTO THE UNSTEADY SHOCK-WAVE TURBULENT BOUNDARY LAYER INTERACTION USING LARGE EDDY SIMULATION
SINOPSIS
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.