arXiv 2003.132522020-03physics.ed-phphysics.ao-phphysics.flu-dyn

剪切流不稳定性的简单演示

A simple demonstration of shear-flow instability

Tom Howard, Ana Barbosa Aguiar

备注：: 22 pages, 8 figures. This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in American Journal of Physics 88, Issue 12, 1041 (2020) and may be found at https://doi.org/10.1119/10.0002438
发表信息：: American Journal of Physics 88, 1041 (2020)
DOI：: 10.1119/10.0002438

摘要：

我们描述了一个简单的课堂演示的流体动力学不稳定性。演示只需要一桶水，一根绳子和一些用过的茶叶或咖啡渣。我们认为，不稳定的机制，至少在其后期阶段，是二维正压（剪切流）不稳定，我们提出的证据支持这一点。我们展示了一个等效的基本二维数值非线性模型的结果，该模型模拟的行为与桶演示中观察到的行为相当。修正的模拟表明，不稳定性不依赖于域的曲率，而是在速度剖面。

英文摘要：

We describe a simple classroom demonstration of a fluid-dynamic instability. The demonstration requires only a bucket of water, a piece of string and some used tealeaves or coffee grounds. We argue that the mechanism for the instability, at least in its later stages, is two-dimensional barotropic (shear-flow) instability and we present evidence in support of this. We show results of an equivalent basic two-dimensional numerical non-linear model, which simulates behavior comparable to that observed in the bucket demonstration. Modified simulations show that the instability does not depend on the curvature of the domain, but rather on the velocity profile.

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