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用作者提出的区域分解、杂交数值模拟方法研究Re数在3000～10000圆柱绕流近尾迹流动转捩特征及旋涡脱落与转捩波这两类不稳定性的时空发展与相互作用。高分辨率速度功率谱分析得到了转捩波频率比随Re数变化新的理论结果,即f_t/f_s～Re~(0.87),符合Wei-Smith的实验规律,与Braza的数值预计及Bloor等的早期实验结果f_t/f_s～Re~(0.5)不同。数值显示了存在于两类旋涡间的多重相互作用现象。理论和数值分析预计了两种独立频率(f_t,f_s)的强非线性相互作用及由此产生的频谱拓宽并形成小涡、耦合频率,揭示了流动的转捩特征。首次给出了转捩波与耦合频率强度沿尾迹下游的变化规律。描述了近尾迹在出现三维变化前流动的转捩特征。
Using the method of regional decomposition and hybridization proposed by the author, the characteristics of the flow around a circular Reynolds number Reynolds number ranging from 3000 to 10000 and the spatiotemporal development and interaction of the vortex shedding and the transition wave are studied. The new theoretical result of the frequency ratio of transition wave with Re number is obtained by high resolution velocity power spectrum analysis, that is, f_t / f_s ~ Re ~ (0.87), which accords with the experimental rule of Wei-Smith, the numerical prediction of Braza and Bloor et al The early experimental results f_t / f_s ~ Re ~ (0.5) are different. The numerical results show the multiple interactions existing between two types of vortices. Theoretical and numerical analysis predict the strong non-linear interaction between the two independent frequencies (f_t, f_s) and the resultant spectrum broadening and the formation of small vortices and coupling frequencies, revealing the transition characteristics of the flow. For the first time, the variation of the transitional wave and the coupling frequency along the downstream of the wake is given. A description of the swirling feature of the near-wake flow before it appears three-dimensional changes.