在有和没有稳定层结的流动中涡结构对涡度拟能和标量输运的作用
Role of vortical structures for enstrophy and scalar transport in flows with and without stable stratification
摘要：
在本文中，我们调查拟能动力学的关系，目标欧拉相干结构（OECSs）和它们的影响拟能和标量输运附近的湍流/非湍流界面（TNTI）的流动和不稳定分层。我们证实，涡拉伸产生拟能内的边界的OECSs，而粘性扩散转移拟能跨越边界的结构。虽然在文献中经常被忽略，涡结构边界内涡拟能的粘性耗散是重要的。相反，对于弱层结流也在这里研究，斜压扭矩的影响是可以忽略的。我们提供的证据表明，OECSs平流的被动/主动标量和重新分配它通过分子扩散。最后，我们使用条件分析表明，典型的配置文件的拟能和标量输运方程项在TNTI是兼容的存在下，位于湍流子层和湍流核心区域之间的边缘的OECS。我们表明，当这些配置文件进一步条件的存在下的OECS，其幅度是相当高的。
英文摘要：
In this paper, we investigate the enstrophy dynamics in relation to objective Eulerian coherent structures (OECSs) and their impact on the enstrophy and scalar transport near the turbulent/non-turbulent interface (TNTI) in flows with and without stable stratification. We confirm that vortex-stretching produces enstrophy inside the boundaries of the OECSs, while viscous diffusion transfers the enstrophy across the boundaries of the structures. Although often overlooked in the literature, viscous dissipation of enstrophy within the boundaries of vortical structures is significant. Conversely, for the weakly stratified flows also investigated here, the effect of the baroclinic torque is negligible. We provide evidence that the OECSs advect the passive/active scalar and redistribute it via molecular diffusion. Finally, we use conditional analysis to show that the typical profiles of the enstrophy and scalar transport equation terms across the TNTI are compatible with the presence of OECSs positioned at the edge between the turbulent sublayer and the turbulent core region. We show that when these profiles are further conditioned to the presence of OECSs, their magnitude is considerably higher.
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