Numerical study on the stabilisation of Tollmien-Schlichting waves by finite amplitude streaks

Authors: Schlatter, P., Brandt, L.B., De Lange, H. C.
Document Type: Conference
Pubstate: Published
Journal: Turbulence and Shear Flow Phenomena - 5
Volume: 2   849-854
Year: 2007


Large-eddy simulations of laminar-turbulent transition due to Tollmien-Schlichting (TS) waves and their control by steady boundary-layer streaks are performed. The streaks are forced at the inflow as optimal solutions to the linear parabolic stability equations (PSE), and the TS-waves are excited via a harmonic volume force (together with small-amplitude noise) within the computational domain . The results show, in agreement with recent experimental and theoretical studies, that significant damping of unstable two-dimensional TS-waves of various frequencies can be obtained. The damping characteristics are mainly dependent on the streak amplitude. A new phenomena is also identified which is characterised by the strong amplification via nonlinear interactions of the second spanwise harmonic of the streak when the streak amplitude is comparable to the TS amplitude. Moreover, visualisations of the flow field are used to highlight the different vortical structures and their interactions that are relevant to this flow case.