Flow unsteadiness and stability characteristics of low-Re flow past an inclined triangular cylinder
Flow unsteadiness and stability characteristics of low-Re flow past an inclined triangular cylinder
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倾斜三角柱低稀土流的流动不稳定性和稳定性特性
DOI：
10.1115/1.4037277
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发表时间：
2017
影响因子：
2
通讯作者：
Zhu Zuchao
中科院分区：
文献类型：
--
作者：
Zhang Wei;Yang Hui;Dou Hua-Shu;Zhu Zuchao
本文研究了Re = 100时二维斜三角柱绕流问题。通过数值模拟，研究了圆柱倾斜对气动参数、非定常流态、时均流动特性和流动非定常性的影响。我们还提供了第一个全局线性稳定性分析和敏感性分析的目标物理问题的流量控制的潜在应用。本文的目的是定量地确定圆柱倾斜对特征量和非定常流态的影响，重点是流动的非定常性和不稳定性。数值结果表明，在α→ 60 °时，前角处出现分离，流动的不稳定性更明显。倾斜圆柱减小了近尾流中的速度不足，并且对于α= 30 °圆柱，远尾流中的减小最显著。最大速度亏缺、最大/最小速度脉动等量的横向分布向负方向移动。全局稳定性和敏感性分析表明，当α≤ 30 °时，扰动速度的空间结构非常相似，扰动速度的时间增长率对近尾流敏感;而当α≥ 40 °时，扰动速度的横向扩展和流向伸长显著，扰动速度的时间增长率对远尾流敏感。
The present study investigates the two-dimensional flow past an inclined triangular cylinder at Re = 100. Numerical simulation is performed to explore the effect of cylinder inclination on the aerodynamic quantities, unsteady flow patterns, time-averaged flow characteristics, and flow unsteadiness. We also provide the first global linear stability analysis and sensitivity analysis on the targeted physical problem for the potential application of flow control. The objective of this work is to quantitatively identify the effect of cylinder inclination on the characteristic quantities and unsteady flow patterns, with emphasis on the flow unsteadiness and instability. Numerical results reveal that the flow unsteadiness is generally more pronounced for the base-facing-like cylinders (α→ 60 deg) where separation occurs at the front corners. The inclined cylinder reduces the velocity deficiency in the near-wake, and the reduction in far-wake is the most notable for theα= 30 deg cylinder. The transverse distributions of several quantities are shifted toward the negativey-direction, such as the maximum velocity deficiency and maximum/minimum velocity fluctuation. Finally, the global stability and sensitivity analysis show that the spatial structures of perturbed velocities are quite similar forα≤ 30 deg and the temporal growth rate of perturbation is sensitive to the near-wake flow, while forα≥ 40 deg there are remarkable transverse expansion and streamwise elongation of the perturbed velocities, and the growth rate is sensitive to the far-wake flow.