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Sustaining mechanism of Taylor–Görtler-like vortices in a streamwise-rotating channel flow
Physical Review Fluids ( IF 2.7 ) Pub Date : 
Zixuan Yang, Bing-Qing Deng, Bing-Chen Wang, and Lian Shen

Energy transport in the spectral space is analyzed to study the mechanism underlying the Taylor–G"ortler-like (TGL) vortices that appear as two layers of streamwise-elongated roll cells in a turbulent channel flow subjected to fast streamwise system rotation. The transport equation of velocity-spectrum tensor in a rotating frame is derived to study the budget balance of energy spectra at different length scales. Two new terms, namely the rotation-induced redistribution term and rotation-induced wall-normal diffusion term, are defined to reflect the effect of the imposed system rotation on the energy transport process. By analyzing the data obtained from direct numerical simulation, it is discovered that four key processes are responsible for sustaining the motion of the TGL vortices. The first process corresponds to the energy production at the characteristic length scales of the TGL vortices that drains energy from the mean flow to the TGL vortices. The second process is the rotation-induced energy redistribution from the streamwise velocity fluctuations to the wall-normal and spanwise velocity fluctuations that form the vortex structures in a cross-stream plane. The third process is the energy diffusion from the near-wall region to the channel center, which is enhanced due to the occurrence of the TGL vortices and in turn feeds energy to the vortices. The last process is the inverse inter-scale energy transfer, through which the large-scale TGL vortices absorb energy from small-scale eddies.

中文翻译:

泰勒-戈特勒样涡在流向旋转通道中的维持机理

第一个过程对应于在TGL涡旋的特征长度尺度上产生的能量,该能量从平均流向TGL涡旋排放能量。第二个过程是旋转引起的能量从流向速度波动到壁面法向和跨向速度波动的再分布,后者在横流平面内形成涡流结构。第三个过程是能量从近壁区域到通道中心的扩散,这是由于TGL涡流的出现而增强的,进而将能量馈送到涡流。最后一个过程是逆尺度间的能量传递,大规模的TGL涡流通过逆向的能量传递来吸收小尺度涡流的能量。第二个过程是旋转引起的能量从流向速度波动到壁面法向和跨向速度波动的再分布,后者在横流平面内形成涡流结构。第三个过程是能量从近壁区域到通道中心的扩散,这是由于TGL涡流的出现而增强的,进而将能量馈送到涡流。最后一个过程是逆尺度间的能量传递,大规模的TGL涡流通过逆向的能量传递来吸收小尺度涡流的能量。第二个过程是旋转引起的能量从流向速度波动到壁面法向和跨向速度波动的再分布,后者在横流平面内形成涡流结构。第三个过程是能量从近壁区域到通道中心的扩散,这是由于TGL涡流的出现而增强的,进而将能量馈送到涡流。最后一个过程是逆尺度间的能量传递,大规模的TGL涡流通过逆向的能量传递来吸收小尺度涡流的能量。由于TGL涡流的出现,它得到了增强,从而又向涡流提供能量。最后一个过程是逆尺度间的能量传递,大规模的TGL涡流通过逆向的能量传递来吸收小尺度涡流的能量。由于TGL涡流的出现,它得到了增强,从而又向涡流提供能量。最后一个过程是逆尺度间的能量传递,大规模的TGL涡流通过逆向的能量传递来吸收小尺度涡流的能量。
更新日期:2020-03-21
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