Volume 9, Issue 2
On the Generation of Instability Tollmien-Schlichting Waves by Free-Stream Turbulence

Luyu Shen and Changgen Lu

10.4208/aamm.2015.m998

Adv. Appl. Math. Mech., 9 (2017), pp. 429-438.

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  • Abstract

The beginning of the transition from the laminar to a turbulent flow is usually the generation of instability Tollmien-Schlichting (T-S) waves in the boundary layer. Previously, most numerical and experimental researches focused on generating instability T-S waves through the external disturbances such as acoustic waves and vortical disturbances interacting with wall roughness or at the leading-edge of flatplate, whereas only a few paid attention to the excitation of the T-S waves directly by free-stream turbulence (FST). In this study, the generating mechanism of the temporal mode T-S waves under free-stream turbulence is investigated by using direct numerical simulation (DNS) and fast Fourier transform. Wave packets superposed by a group of stability, neutral and instability T-S waves are discovered in the boundary layer. In addition, the relation between the amplitude of the imposed free-stream turbulence and the amplitude of the excited T-S wave is also obtained.

  • History

Published online: 2018-05

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