On the spiking stages in deep transition and unsteady separation
On the spiking stages in deep transition and unsteady separation
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DOI：
10.1023/a:1022677807035
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发表时间：
2003-04-01
影响因子：
1.3
通讯作者：
Smith, FT
中科院分区：
文献类型：
--
作者：
Bowles, RI;Davies, C;Smith, FT
数值模拟的一个大振幅的非线性二维列车的Tollmien-Schlichting波进行第一次和显示的发展短尺度结构或尖峰。详细描述的尖峰过程及其随后的发展给出描述本地化的最大值的产生在流向的压力分布和相关的涡流，尖峰在扰动速度跟踪和出现强壁法向压力梯度。一个高雷诺数的渐近理论以前已经开发了两个作者，其目的是描述这个尖峰过程。目前的工作是第一个给出这个理论和平面Navier-Stokes计算之间的比较。我们给出了一个简单的描述的理论，显示正常的压力梯度如何变得活跃和他们的作用，在产生的流向压力分布和随后的影响，如涡流的产生和壁层涡爆发。演示文稿给出了密切的定性参考的模拟，因此给予信任的相关性的理论帐户和解释该帐户的物理条件。比较，虽然主要是定性的，是成功的，因为它是可以识别的物理过程中强调的理论在计算中，从而澄清复杂的流体运动，并提出进一步的研究方向。本文的结论与第一个讨论的模拟和理论的结果可以用来了解类似的过程中看到的非定常平面分离，其次，他们的相关性强的三维过程中工作的深过渡实验。
Numerical simulations of a large-amplitude nonlinear two-dimensional train of Tollmien-Schlichting waves are performed first and show the development of short-scaled structures or spikes. A careful description of the spiking process and its subsequent development is given describing the generation of localized maxima in the streamwise pressure distribution and associated vortices, spikes in a perturbation velocity trace and the emergence of strong wall-normal pressure gradients. A high-Reynolds-number asymptotic theory has previously been developed by two of the authors which aims to describe this spiking process. The current work is the first to give a comparison between this theory and planar Navier-Stokes computations. We give a brief description of the theory showing how normal pressure gradients become active and their role in the generation of the streamwise pressure distribution and its subsequent effects such as vortex generation and wall-layer vorticity eruptions. The presentation is given with close qualitative reference to the simulations, so giving credence to the relevance of the theoretical account and an interpretation of that account in physical terms. The comparison, although primarily qualitative, is successful in that it is possible to identify the physical processes highlighted by the theory in the computations, so clarifying the complex fluid motions and suggesting directions for further research. The paper concludes with firstly a discussion of how the results of the simulations and the theory could be used to give an understanding of similar processes seen in unsteady planar separation and secondly their relevance to the strongly three-dimensional processes at work in deep transition experiments.