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LOW-ORDER MODEL FOR THE LOW-FREQUENCY UNSTEADINESS IN OBLIQUE-SHOCK/TURBULENT-BOUNDARY-LAYER INTERACTIONS

Emile Touber
Department of Aeronautics, Imperial College London, South Kensington Campus, London SW7 2AZ, U.K.

Neil D. Sandham
Aerodynamics and Flight Mechanics Group Faculty of Engineering and the Environment, University of Southampton Southampton SO17 1BJ, UK

Résumé

The interaction between a turbulent supersonic boundary layer and an impinging shock wave is investigated numerically and analytically. The reflected-shock low-frequency motions are well captured even when using a narrow simulation domain, supporting the argument that one underlying key mechanism for the low-frequency shock motions is two dimensional. Based on a two-dimensional approach, a stochastic ordinary differential equation for the low-frequency coupling between the reflected shock and the boundary layer is obtained. The system is closed and applied to a wide range of input parameters. It is argued that the low-frequency shock motions are not necessarily a property of the forcing, either from upstream or downstream of the shock, but are simply an intrinsic property of the coupled dynamical system.