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首页> 外文期刊>International Journal of Heat and Fluid Flow >Shearless and sheared flow past a circular cylinder: Comparative analysis by means of LES
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Shearless and sheared flow past a circular cylinder: Comparative analysis by means of LES

机译：通过圆柱的无剪切流和剪切流：借助LES的比较分析

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Large eddy simulation (LES) of the uniform shear flow past a circular cylinder at Reynolds number Re_D = 3900 with increasingly enhanced mean shear magnitude |du_F/dy| corresponding to the shear rate (SR = |du_F/dy|D/u_F) range between 0 (shearless flow) and 0.177 have been performed in order to provide a basis for comparative analysis of the shear-induced effects with respect to the structural characterization of the cylinder wake. The case characterized by the velocity gradient being perpendicular to the cylinder axis was considered. In addition to the direct comparison of the present computational results with the reference database (mean velocity and Reynolds stress profiles at selected locations in the near and the far wake), the results presentation includes pressure field around the cylinder, mean pathlines inside and outside the separation bubble, vortex structure visualization by the pressure fluctuations and Q-cri-terion as well as the Reynolds stress anisotropy evolution and energy budgets of the Reynolds stress components and the kinetic energy of turbulence. An important outcome arising from the present computational study relates to the asymmetric shape of the mean quantity profiles with the local maxima/minima shifted to the high velocity side, indicating a strong modulation of the large-scale structures in the wake due to the imposed mean shear. It applies especially to the far wake region. Here, the structures illustrated by the fluctuating pressure field clearly show their existence only on the high velocity side. In contrast, the small-scale structures remain almost unaffected by the mean shear. Evaluation of the lift forces from the velocity and pressure fields illustrate an increasing magnitude with the shear rate towards the lower velocity side, in good agreement with corresponding experiments.
机译：通过雷诺数Re_D = 3900的圆柱体的均匀剪切流的大涡模拟（LES），平均剪切强度| du_F / dy |逐渐增大对应于剪切速率（SR = | du_F / dy | D / u_F）的范围在0（无剪切流）和0.177之间，以便为比较分析结构特性引起的剪切诱导效应提供基础圆柱唤醒。考虑了以速度梯度垂直于圆柱轴为特征的情况。除了将当前计算结果与参考数据库（在近尾和远尾选定位置的平均速度和雷诺应力分布图）进行直接比较之外，结果显示还包括圆柱体周围的压力场，圆柱体内部和外部的平均路径。分离气泡，通过压力波动和Q准则以及雷诺应力各向异性演化和雷诺应力分量的能量收支以及湍流动能的能量平衡可视化涡流结构。当前计算研究的一个重要结果涉及平均量轮廓的不对称形状，局部最大值/最小值移到了高速侧，这表明由于强加了平均值，尾流中大型结构的强烈调制剪。它尤其适用于遥远地区。在此，由波动的压力场表示的结构仅在高速侧清楚地显示出它们的存在。相反，小规模结构几乎不受平均剪切力的影响。从速度场和压力场对升力的评估表明，随着剪切速率朝着较低的速度侧，幅度增大，这与相应的实验非常吻合。

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