Large-Eddy Simulations of an Oblique Shock Impinging on a Turbulent Boundary Layer: Effect of the Spanwise Confinement on the Low-Frequency Oscillations
The low-frequency motions found in two large-eddy simulations of the same oblique-shock/turbulent-boundary-layer interaction with significantly different domain widths are investigated. The narrow domain artificially confines the shock-induced separation bubble, which is seen to grow significantly. In addition, the low-frequency/large-amplitude shock oscillations are found to be enhanced, therefore suggesting that they originate from an intrinsic two-dimensional mechanism. By reducing the spanwise confinement, large coherent structures as wide as one separation-bubble length are found to develop inside the interaction. Those structures can move sideways and survive for extended periods of time. Their proper resolution is therefore challenging in terms of computational cost and their meandering motions can significantly bias the interpretation of a spectral analysis performed at a fixed point.
KeywordsTurbulent Boundary Layer Separation Bubble Oblique Shock Supersonic Boundary Layer Shock Oscillation
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