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.

我们研究了与客观欧拉相干结构 (OECS) 相关的熵动力学及其对湍流/非湍流界面 (TNTI) 附近有和没有稳定分层的流中的熵和标量输运的影响。我们确认涡旋拉伸在 OECS 的边界内产生了内摄，而粘性扩散将内摄转移到了结构的边界。尽管在文献中经常被忽视，但涡旋结构边界内的熵增粘性耗散是很重要的。相反，对于这里也研究的弱分层流动，斜压扭矩的影响可以忽略不计。我们提供证据表明 OECSs 平流被动/主动标量并通过分子扩散重新分配它。最后，我们使用条件分析来表明整个 TNTI 的熵和标量输运方程项的典型剖面与位于湍流子层和湍流核心区域之间边缘的 OECS 的存在兼容。我们表明，当这些剖面进一步适应 OECS 的存在时，它们的量级要高得多。