Microbubble effect on friction drag reduction in a turbulent boundary layer
Microbubble effect on friction drag reduction in a turbulent boundary layer
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微气泡对湍流边界层摩擦阻力减少的影响
DOI：
10.1016/j.oceaneng.2020.107583
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发表时间：
2020-09
影响因子：
5
通讯作者：
Yu Zhou
中科院分区：
文献类型：
--
作者：
Yan-Yan Feng;Hong Hu;Guo-Yi Peng;Yu Zhou
采用大涡模拟方法研究了微气泡对湍流边界层摩擦阻力的影响。通过引入扰动，在来流近距离内产生雷诺数Re θ= 1430的平板湍流边界层。研究的参数包括重力，注射高度，和微泡的体积分数。结果表明，微气泡的减阻机理有三个方面，即微气泡的浮力作用、拟序结构的改变和近壁流体动力学粘性。在不同的条件下，减阻的主导机制是不同的。随着微气泡在平板上方注入，主要机制是相干结构从壁面的升力和流向涡的尺寸和涡度的减小。当微气泡体积分数增加时，作用在微气泡上的浮力越大，共格结构越远离壁面，减阻效果越好。随着微气泡注入平板下方，主要机制是流体动力学粘度显著降低，因为浮力推动微气泡聚集在壁附近并形成薄空气层。减阻率高于在平板上方注入的微气泡。
Effects of microbubbles injection on friction drag in a turbulent boundary layer are studied using large-eddy simulation. A flat-plate turbulent boundary layer with a Reynolds numberReθ= 1430 is generated within a short distance of inflow by introducing disturbances. The parameters investigated include the gravity, the injection height, and the volume fraction of microbubbles. It is found that the mechanism for drag reduction is threefold, that is, buoyancy acting on microbubbles, the change of coherent structures, and hydrodynamic viscosity near the wall. Under different conditions, the dominant mechanism for drag reduction varies among them. With microbubbles injected above the flat plate, the primary mechanism is the lift of coherent structures from the wall and the decrease in the size and vorticity of the streamwise vortices. When microbubble volume fraction increases, the larger buoyancy acting on microbubbles leads to coherent structures shifted further away from the wall, resulting in higher drag reduction. With microbubbles injected beneath the flat plate, the dominant mechanism is a significant decrease in hydrodynamic viscosity as buoyancy pushes microbubbles gathering near the wall and forming a thin air layer. The drag reduction is higher than that of microbubbles injected above the flat plate.
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影响因子：
2.6
作者：
N. Sandham;Yufeng Yao;A. Lawal
通讯作者：
N. Sandham;Yufeng Yao;A. Lawal
DOI：
--
发表时间：
2015
期刊：
--
影响因子：
--
作者：
J. Jiménez
通讯作者：
J. Jiménez
影响因子：
2.6
作者：
M. M. Guin-M.;H. Kato;H. Yamaguchi;M. Maeda;M. Miyanaga
通讯作者：
M. M. Guin-M.;H. Kato;H. Yamaguchi;M. Maeda;M. Miyanaga
影响因子：
2.6
作者：
Yasuhiro Moriguchi;H. Kato
通讯作者：
Yasuhiro Moriguchi;H. Kato
影响因子：
2.5
作者：
Cheng-sheng Wu;Shu-long He;De-xiang Zhu;Mingzhou Gu
通讯作者：
Cheng-sheng Wu;Shu-long He;De-xiang Zhu;Mingzhou Gu