论文标题
旋转湍流中的相变和通量环的亚稳态状态
Phase transitions and flux-loop metastable states in rotating turbulence
论文作者
论文摘要
通过使用512x512x32768网格点的直接数值模拟，我们发现在旋转湍流中存在新的亚稳态不平衡状态。我们通过改变旋转速率（与Rossby数字成正比，$ RO $）和无量纲长宽比（$λ= H/L $）来扫描相位空间，其中$ l $和$ h $是范围的尺寸，分别与旋转方向平行。我们显示了三个湍流相的存在。对于小$ ro $，但有限的$λ$，我们有一个分裂的级联，其中注入的能量都会转移到大型和小尺度上。对于大$λ$和有限$ ro $，没有反向级联反应，并且能量仅在傅立叶空间中转移。令人惊讶的是，在这两个制度之间，第三阶段观察到此处首次报道。 Consequently, for certain intervals of $Ro$ and $λ$, energy is no longer accumulated at arbitrarily large scales, rather it stops at some characteristic intermediate length-scales from where it is then redistributed forward in Fourier space, leading to a flux-loop mechanism where the flow is out of equilibrium with vanishing net flux, and non-vanishing heterochiral and homochiral sub-fluxes.该系统的进一步特征是具有亚稳定性和批判性减慢，解释了为什么以前的实验和数值模拟无法检测到这种现象，需要很长的观察时间和庞大的计算资源。
By using direct numerical simulations of up to a record resolution of 512x512x32768 grid points we discover the existence of a new metastable out-of-equilibrium state in rotating turbulence. We scan the phase space by varying both the rotation rate (proportional to the inverse of the Rossby number, $Ro$) and the dimensionless aspect ratio, $λ=H/L$, where $L$ and $H$ are the sizes of the domain perpendicular and parallel to the direction of rotation, respectively. We show the existence of three turbulent phases. For small $Ro$ but finite $λ$, we have a split cascade where the injected energy is transferred to both large and small scales. For large $λ$ and finite $Ro$ there is no inverse cascade and the energy is transferred forward in Fourier space only. Surprisingly, between these two regimes, a third phase is observed as reported here for the first time. Consequently, for certain intervals of $Ro$ and $λ$, energy is no longer accumulated at arbitrarily large scales, rather it stops at some characteristic intermediate length-scales from where it is then redistributed forward in Fourier space, leading to a flux-loop mechanism where the flow is out of equilibrium with vanishing net flux, and non-vanishing heterochiral and homochiral sub-fluxes. The system is further characterized by the presence of metastability and critical slowing down, explaining why previous experiments and numerical simulations were not able to detect this phenomenon, requiring extremely long observation time and huge computational resources.
