Bypass transition and spot nucleation in boundary layers
Bypass transition and spot nucleation in boundary layers
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DOI：
10.1103/physrevfluids.1.043602
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发表时间：
2016-08-01
影响因子：
2.7
通讯作者：
Eckhardt, Bruno
中科院分区：
文献类型：
--
作者：
Kreilos, Tobias;Khapko, Taras;Eckhardt, Bruno
时空方面的过渡到湍流被认为是在一个边界层流动的情况下，上面的平板暴露于自由流湍流发展。结合结果的感受性自由流湍流的非线性概念的过渡阈值，一个物理动机的模型表明，点成核事件的空间分布。为了描述湍流斑的演化，引入了概率元胞自动机，所有参数直接从边界层的数值模拟获得。然后结合成核率与元胞自动机模型，产生良好的定量协议的统计特性，不同的自由流湍流水平。因此，我们展示了如何过渡壁有界流动的最新理论进展，可以扩展到更广泛的一类空间发展的边界层流动。
The spatiotemporal aspects of the transition to turbulence are considered in the case of a boundary-layer flow developing above a flat plate exposed to free-stream turbulence. Combining results on the receptivity to free-stream turbulence with the nonlinear concept of a transition threshold, a physically motivated model suggests a spatial distribution of spot nucleation events. To describe the evolution of turbulent spots a probabilistic cellular automaton is introduced, with all parameters directly obtained from numerical simulations of the boundary layer. The nucleation rates are then combined with the cellular automaton model, yielding excellent quantitative agreement with the statistical characteristics for different free-stream turbulence levels. We thus show how the recent theoretical progress on transitional wall-bounded flows can be extended to the much wider class of spatially developing boundary-layer flows.