Extension at the downstream end of turbulent band in channel flow

In this Letter, the velocity structures and the extension behavior of localized turbulent bands in channel flows are measured by particle image velocimetry in a plane parallel to the walls and are analyzed by comparing with direct numerical simulations at low Reynolds numbers. It is illustrated that...

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Bibliographic Details
Published in:Physics of fluids (1994) 2020-12, Vol.32 (12)
Main Authors: Liu, Jinsheng, Xiao, Yue, Zhang, Linsen, Li, Mogeng, Tao, Jianjun, Xu, Shengjin
Format: Article
Language:English
Subjects:
Banded structure
Channel flow
Computational fluid dynamics
Convection
Direct numerical simulation
Fluid dynamics
Fluid flow
Low speed
Particle image velocimetry
Physics
Solitary waves
Turbulent flow
Velocity
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Summary:In this Letter, the velocity structures and the extension behavior of localized turbulent bands in channel flows are measured by particle image velocimetry in a plane parallel to the walls and are analyzed by comparing with direct numerical simulations at low Reynolds numbers. It is illustrated that the convection velocity of the band head (band’s downstream end) is not determined by the formation and propagation of low-speed streaks but by a high-speed “hat” shaped region near the band head. This “hat” region travels downstream obliquely like a solitary wave and leaves newly generated low-speed streaks to travel slowly in the spanwise direction, leading to the head extension of turbulent bands.
ISSN:1070-6631
1089-7666
DOI:10.1063/5.0032272