Backflow structures in turbulent pipe flows at low to moderate Reynolds numbers
Backflow structures in turbulent pipe flows at low to moderate Reynolds numbers
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低到中等雷诺数的湍流管流中的回流结构
DOI：
10.1017/jfm.2023.461
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发表时间：
2023
影响因子：
3.7
通讯作者：
Chen X
中科院分区：
文献类型：
--
作者：
Chen X
研究了雷诺数小于或等于时，壁面有界流动中回流结构的统计特性和演化规律。回流是由壁面附近的大型高速和低速结构连接引起的，并在低速结构的尾部形成。随着雷诺数的增加，回流结构的分布密度和壁上回流区的面积百分比均增大。回流结构的平均寿命为8个壁单位，在管道中被发现略长于渠道，并且它们以大约10个壁单位的缓冲区的平均速度向下游对流，类似于Cardesa等人。(《流体机械》，第880卷，2019年，R3)。回流结构偶尔会分裂和合并，并可形成与壁面分离的结构。证据表明，裂解、合并和壁分离回流结构是由近壁结构引起的。裂解回流结构平均较大，跨向拉长较多，由于近壁条纹的跨向剪切而分裂。当其载体低速结构的尾端‘坐’在近壁高速条纹上时，形成与壁面分离的回流结构。当经历与具有跨向伸长的正常增长和衰退的回流相似的生命周期时，壁分离的回流结构往往通过接近壁面而变得附壁，这是因为在缓冲区中由持续的涡流结构驱动的高速结构将位于低速结构尾部的回流区持续向下压向壁面。
The statistical characteristics and the evolution of the backflow structures are investigated in wall-bounded flows at Reynolds numbers up to . The backflow is caused by the joining of large-scale high- and low-speed structures in the vicinity of the wall and is formed at the tail tip of the low-speed structure. The distribution density of the backflow structures and the percentage area of the backflow region on the wall both increase with the Reynolds number. The backflow structures have an average lifespan of 8 wall units which is found to be slightly longer in the pipe than the channel, and they are convected downstream at the average velocities of the buffer region of approximately 10 wall units, similar to Cardesa et al. (J. Fluid Mech., vol. 880, 2019, R3). The backflow structures occasionally split and merge, and can form detached from the wall. Evidence shows that the split, merged and wall-detached backflow structures are caused by the near-wall structures. The split backflow structures are on average, larger and more spanwise-elongated which are split due to the spanwise shearing of the near-wall streaks. A backflow structure is formed detached from the wall when the trailing end of its carrier low-speed structure ‘sits’ on the near-wall high-speed streaks. The wall-detached backflow structures tend to become wall-attached by approaching the wall when undergoing a similar life cycle to the normal backflow of growth and decay with spanwise elongation because the backflow region at the tail of the low-speed structure is continuously pressed down to the wall by the high-speed structure driven by persistent vortical structures in the buffer region.
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DOI：
10.1016/j.ijheatfluidflow.2021.108817
发表时间：
2021-08
影响因子：
2.6
作者：
Xue Chen;Yongmann M. Chung;M. Wan
通讯作者：
Xue Chen;Yongmann M. Chung;M. Wan
影响因子：
3.7
作者：
L. Hellström;B. Ganapathisubramani;A. Smits
通讯作者：
L. Hellström;B. Ganapathisubramani;A. Smits
影响因子：
1.9
作者：
R. Vinuesa;R. Örlü;P. Schlatter
通讯作者：
P. Schlatter
影响因子：
3.7
作者：
M. Bross;T. Fuchs;C. Kähler
通讯作者：
M. Bross;T. Fuchs;C. Kähler
零压力梯度平板边界层以及具有滑移和无滑移边界条件的管流中过渡期间的负表面摩擦
影响因子：
3.7
作者：
Xiaohua Wu;Michael C. Cruickshank;S. Ghaemi
通讯作者：
S. Ghaemi