• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文OA文献 >Oblique and parallel modes of vortex shedding in the wake of a circular cylinder at low Reynolds numbers
【2h】

Oblique and parallel modes of vortex shedding in the wake of a circular cylinder at low Reynolds numbers

机译：低雷诺数圆柱绕流后斜涡和平行涡脱落的模式。

代理获取
本网站仅为用户提供外文OA文献查询和代理获取服务，本网站没有原文。下单后我们将采用程序或人工为您竭诚获取高质量的原文，但由于OA文献来源多样且变更频繁，仍可能出现获取不到、文献不完整或与标题不符等情况，如果获取不到我们将提供退款服务。请知悉。
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Two fundamental characteristics of the low-Reynolds-number cylinder wake, which have involved considerable debate, are first the existence of discontinuities in the Strouhal-Reynolds number relationship, and secondly the phenomenon of oblique vortex shedding. The present paper shows that both of these characteristics of the wake are directly related to each other, and that both are influenced by the boundary conditions at the ends of the cylinder, even for spans of hundreds of diameters in length. It is found that a Strouhal discontinuity exists, which is not due to any of the previously proposed mechanisms, but instead is caused by a transition from one oblique shedding mode to another oblique mode. This transition is explained by a change from one mode where the central flow over the span matches the end boundary conditions to one where the central flow is unable to match the end conditions. In the latter case, quasi-periodic spectra of the velocity fluctuations appear; these are due to the presence of spanwise cells of different frequency. During periods when vortices in neighbouring cells move out of phase with each other, ‘vortex dislocations’ are observed, and are associated with rather complex vortex linking between the cells. However, by manipulating the end boundary conditions, parallel shedding can be induced, which then results in a completely continuous Strouhal curve. It is also universal in the sense that the oblique-shedding Strouhal data (S_θ) can be collapsed onto the parallel-shedding Strouhal curve (S_0) by the transformation, S_0 = S_θ/cosθ, where θ is the angle of oblique shedding. Close agreement between measurements in two distinctly different facilities confirms the continuous and universal nature of this Strouhal curve. It is believed that the case of parallel shedding represents truly two-dimensional shedding, and a comparison of Strouhal frequency data is made with several two-dimensional numerical simulations, yielding a large disparity which is not clearly understood. The oblique and parallel modes of vortex shedding are both intrinsic to the flow over a cylinder, and are simply solutions to different problems, because the boundary conditions are different in each case.
机译：低雷诺数圆柱尾流的两个基本特征引起了广泛的争论，首先是斯特劳哈尔-雷诺数关系中存在不连续性，其次是斜涡旋脱落现象。本论文表明，尾流的这两个特性彼此直接相关，并且即使在长度为数百个直径的跨度时，两者也受圆柱体端部边界条件的影响。发现存在斯特劳哈尔不连续，这不是由于任何先前提出的机制，而是由从一种倾斜脱落模式过渡到另一种倾斜模式引起的。通过从一种模式的转换来解释这种过渡，在这种模式下，跨度上的中心流与末端边界条件相匹配，而在该模式下，中心流无法与末端条件相匹配。在后一种情况下，出现了速度波动的准周期谱；这些是由于存在不同频率的展向单元所致。在相邻单元格中的涡旋彼此异相的期间，观察到“涡旋位错”，并且与单元格之间相当复杂的涡旋联系相关。但是，通过操纵端部边界条件，可以引起平行脱落，然后形成完全连续的Strouhal曲线。在这种意义上，通用的是斜斜Strouhal数据（S_θ）可以通过变换S_0 =S_θ/cosθ折叠到平行斜切Strouhal曲线（S_0）上，其中θ是斜脱落的角度。在两个截然不同的设施中进行的测量之间的紧密一致，证实了该Strouhal曲线的连续性和普遍性。据信，平行脱落的情况代表了真正的二维脱落，并且通过几个二维数值模拟对斯特劳哈尔频率数据进行了比较，从而产生了很大的差异，这一点尚不清楚。涡旋脱落的斜向和平行模式都是圆柱体上的流动所固有的，并且仅仅是解决不同问题的方法，因为边界条件在每种情况下都是不同的。

著录项

  • 作者

    Williamson C. H. K.;

  • 作者单位
  • 年度 1989
  • 总页数
  • 原文格式 PDF
  • 正文语种 {"code":"en","name":"English","id":9}
  • 中图分类

相似文献

  • 外文文献
  • 中文文献
  • 专利
代理获取

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号