Instability and transition of flow past two tandem circular cylinders
Instability and transition of flow past two tandem circular cylinders
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DOI：
10.1063/1.2104689
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发表时间：
2005-10
影响因子：
4.6
通讯作者：
J. Mizushima;Norihisa Suehiro
中科院分区：
文献类型：
--
作者：
J. Mizushima;Norihisa Suehiro
用数值方法研究了两圆柱串列流动的不稳定性和过渡。在小雷诺数下实现稳定的对称流动，但在超过临界雷诺数时，流动变得不稳定，并向振荡流动过渡。对对称流进行了数值模拟，并应用线性稳定性理论分析了对称流的稳定性。通过数值模拟和对平衡解的直接数值计算，得到了不稳定引起的非线性振荡流动，并给出了非线性平衡解的分岔图。我们将注意力集中在两个气缸之间的间隙间距对流动稳定性和过渡的影响上。流动从稳态到振荡状态的转变澄清了由于依赖于间隙间距的超临界或亚临界霍普夫分岔而发生。我们发现，在一定的间隙间距范围内，当间隙间距连续变化时，阻力系数、升力系数和Strouhal数等物理量会发生突变。我们确定了突变的起源是流的多个稳定解的存在。
The instability and transition of flow past two circular cylinders arranged in tandem are investigated numerically. A steady symmetric flow is realized at small Reynolds numbers, but the flow becomes unstable above a critical Reynolds number and makes a transition to an oscillatory flow. We obtained the symmetric flow numerically and analyze its stability by applying linear stability theory. The nonlinear oscillatory flow arising from the instability is obtained not only by numerical simulation but also by direct numerical calculation of the equilibrium solution, and the bifurcation diagram for the nonlinear equilibrium solution is depicted. We focused our attention on the effect of the gap spacing between the two cylinders on the stability and transition of the flow. The transition of the flow from a steady state to an oscillatory state is clarified to occur due to a supercritical or subcritical Hopf bifurcation depending upon the gap spacing. We found that there is a certain range of the gap spacing where physical quantities such as the drag and lift coefficients and the Strouhal number show an abrupt change when the gap spacing is continuously changed. We identified the origin of the abrupt change as the existence of multiple stable solutions for the flow.