Transition mechanism behind a backward-facing step in a supersonic flow

Transition mechanism behind a backward-facing step in a supersonic flow

Hu, W. (TU Delft Aerodynamics)
Hickel, S. (TU Delft Aerodynamics)
van Oudheusden, B.W. (TU Delft Aerodynamics)

2019-01-01

The path of laminar-to-turbulent transition behind a backward-facing step (BFS) in the supersonic regime at Ma = 1.7 and Re_δ0 = 13718 is investigated using a very well-resolved large eddy simulation (LES). Five distinct stages are identified in the transition process by the visualisation of instantaneous flow. The transition is initiated by a Kelvin-Helmholtz (K-H) instability of the separated shear layer, followed by secondary modal instabilities of the distorted K-H vortices, leading to Λ-shaped vortices, hair-pin vortices and finally to a fully turbulent state around the reattachment location. Spectral analysis and proper orthogonal decomposition (POD) reveal that the low-frequency breathing dynamics also plays a major role in the transition process.

http://resolver.tudelft.nl/uuid:e4f14269-f632-48da-a3e5-419832c7b825

Proceedings of the 11th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2019: 30/07/19 - 2/08/19 Southampton, United Kingdom

11th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2019, 2019-07-30 → 2019-08-02, Southampton, United Kingdom

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© 2019 W. Hu, S. Hickel, B.W. van Oudheusden