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arXiv 2310.11642physics.flu-dyn
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具有垂直不对称粗糙壁面的Taylor-Couette流动的直接数值模拟

Direct numerical simulation of Taylor-Couette flow with vertical asymmetric rough walls

Fan Xu, Jinghong Su, Bin Lan, Peng Zhao, Yurong He, Chao Sun, Junwu Wang

AI总结:

本文通过直接数值模拟研究了垂直不对称粗糙壁面旋转方向对Taylor-Couette流动输运特性的影响,发现高Taylor数下顺时针旋转因更强的壁面-体相耦合、湍流强度和压力贡献而产生显著更大的扭矩增强。

摘要:

进行了直接数值模拟,以探究垂直不对称粗糙壁面旋转方向对Taylor-Couette(TC)流动输运特性的影响,Taylor数最高达到Ta = 2.39 × 10^7。结果表明,与光滑壁面相比,带有垂直不对称条纹的粗糙壁面可以增强无量纲扭矩Nu_ω;更重要的是,在高Ta下,内粗糙壁面顺时针旋转(流体受条纹较陡坡度侧剪切)相比于逆时针旋转(流体受条纹较小坡度侧剪切)产生了显著更大的扭矩增强,这是由于对角速度通量的对流贡献更大,尽管在低Ta下旋转方向对扭矩的影响可以忽略不计。高Ta下垂直不对称粗糙壁面顺时针旋转引起的更大扭矩增强,随后通过以下机制进行了解释:由于TC系统中部间隙处偏向粗糙壁面的更大方位角速度,粗糙壁面与体相之间更强的耦合;以更大雷诺应力和更薄边界层表现出的湍流强度增加;以及粗糙壁面表面的压力对扭矩更显著的贡献。

英文摘要:

Direct numerical simulations are performed to explore the effects of rotating direction of the vertical asymmetric rough wall on the transport properties of Taylor-Couette (TC) flow up to a Taylor number of $\textit{Ta} = 2.39 \times 10^7$. It is shown that compared to the smooth wall, the rough wall with vertical asymmetric strips can enhance the dimensionless torque \textit{Nu}$_ω$, and more importantly, at high \textit{Ta} clockwise rotation of the inner rough wall (the fluid is sheared by the steeper slope side of the strips) results in a significantly bigger torque enhancement as compared to the counter-clockwise rotation (the fluid is sheared by the smaller slope side of the strips) due to the larger convective contribution to the angular velocity flux, although the rotating direction has a negligible effect on the torque at low \textit{Ta}. The larger torque enhancement caused by the clockwise rotation of vertical asymmetric rough wall at high \textit{Ta} is then explained by the stronger coupling between the rough wall and the bulk due to the larger biased azimuthal velocity towards the rough wall at the mid-gap of TC system, the increased intensity of turbulence manifesting by larger Reynolds stress and thinner boundary layer, and the more significant contribution of the pressure force on the surface of rough wall to the torque.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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