Influence of confinement on a two-dimensional wake
Influence of confinement on a two-dimensional wake
复制标题
约束对二维尾流的影响
DOI：
10.1017/jfm.2011.376
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发表时间：
2011
影响因子：
3.7
通讯作者：
R. Pasquetti
中科院分区：
文献类型：
--
作者：
L. Biancofiore;F. Gallaire;R. Pasquetti
摘要采用谱Chebyshev多域方法，通过直接数值模拟（DNS），研究了两个滑动平板约束的不可压缩二维粘性尾流的时空发展。不稳定和稳定的配置之间的限制是确定相对于几个无量纲参数：约束，速度比和两个不同的雷诺数，100 $和500 $。这种极限曲线与Juniper（J. Fluid Mech.，第565卷，2006年，pp. 171-195）证实了在中等限制下存在不稳定性最大的区域。此外，不稳定性下也观察到持续的并流，在一个摇摆的前的形式。使用一个直接计算的二维基流，我们执行一个局部线性稳定性分析的几个速度分布在不同的空间位置，以确定当地的时空性质的流动：对流不稳定或绝对不稳定。DNS和本地稳定性分析结果的比较和讨论。
Abstract The spatio-temporal development of an incompressible two-dimensional viscous wake flow confined by two flat slipping plates is investigated by means of direct numerical simulation (DNS), using a spectral Chebyshev multi-domain method. The limit between unstable and stable configurations is determined with respect to several non-dimensional parameters: the confinement, the velocity ratio and two different Reynolds numbers, $100$ and $500$. The comparison of such limit curves with theoretical results obtained by Juniper (J. Fluid Mech., vol. 565, 2006, pp. 171–195) confirms the existence of a region at moderate confinement where the instability is maximal. Moreover, instabilities are also observed under sustained co-flow, in the form of a vacillating front. Using a direct computation of the two-dimensional base flow, we perform a local linear stability analysis for several velocity profiles prevailing at different spatial locations, so as to determine the local spatio-temporal nature of the flow: convectively unstable or absolutely unstable. Comparisons of the DNS and local stability analysis results are provided and discussed.