Abstract

Results are presented for nonlinear equilibrium solutions of the Navier–Stokes equations in the boundary layer set up by a flat plate started impulsively from rest. The solutions take the form of a wave–roll–streak interaction, which takes place in a layer located at the edge of the boundary layer. This extends previous results for similar nonlinear equilibrium solutions in steady 2D boundary layers. The results are derived asymptotically and then compared to numerical results obtained by marching the reduced boundary-region disturbance equations forward in time. It is concluded that the previously found canonical free-stream coherent structures in steady boundary layers can be embedded in unbounded, unsteady shear flows.

中文翻译：

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非稳态瑞利边界层中的自由流相干结构

摘要

给出了由静止冲动开始的由平板建立的边界层中Navier–Stokes方程的非线性平衡解的结果。这些解决方案采取波浪-滚动-条纹相互作用的形式，该相互作用发生在边界层边缘的一层中。这扩展了先前在稳定2D边界层中类似非线性平衡解的结果。渐近地得出结果，然后将其与通过将缩减的边界区域扰动方程及时向前行进而获得的数值结果进行比较。结论是，先前在稳定边界层中发现的规范自由流相干结构可以嵌入无界，不稳定的剪切流中。