Development of streak instability modes excited by turbulent fluctuations

[摘要] Development of streak instability modes excited by disturbances whose frequency-spectrum was similar to that of wall turbulence was examined experimentally for a single screen-generated low-speed streak. The disturbances were introduced into the low-speed streak through two small holes made on both the sides of the low-speed streak. The result showed that even when the low-speed streak was forced by turbulent fluctuations with zero spanwise correlation, sinuous instability modes were excited with distinct frequency selectivity around the most unstable frequency of the linear streak instability and dominated streak breakdown in the downstream region. The magnitude of the sinuous modes excited was compared to the case when the anti-symmetric forcing with the same turbulence spectrum was applied.

[发布机构] Department of Aerospace Engineering, Tokyo Metropolitan University, 6-6 Asahigaoka, Hino, Tokyo; 191-0065, Japan^1

[效力级别] 力学 [学科分类] 力学，机械学

[关键词] Downstream region;Frequency selectivity;Frequency spectra;Instability modes;Spanwise correlation;Turbulence spectrum;Turbulent fluctuation;Wall turbulence