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arXiv 2501.07079physics.flu-dynphysics.comp-ph
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快速旋转湍流中的非平衡连续相变

Nonequilibrium Continuous Transition in a Fast Rotating Turbulence

Chandra Shekhar Lohani, Suraj Kumar Nayak, Kannabiran Seshasayanan, Vishwanath Shukla

AI总结:

该研究通过直接数值模拟与线性稳定性简化模型,发现快速旋转湍流随旋转速率变化的二维-准二维态转变为非平衡连续临界相变,明确了序参量标度、开关间歇性及临界转速与强迫波数的线性关系。

摘要:

我们采用直接数值模拟(DNSs,即Direct Numerical Simulations)研究了快速旋转湍流中三维不稳定扰动的饱和机制。在Kolmogorov强迫作用下,随着全局旋转速率的改变,我们观测到系统从以相干二维模式为主的状态向具有三维变化的准二维状态的转变。我们发现这一现象类似于临界现象,其中序参量与到临界点的距离的幂次呈标度关系,且该幂指数偏离了预测的平均场值。此外,临界点附近序参量的涨落特征表明存在开关间歇性(on-off intermittency)。发生相变的临界旋转速率与强迫波数呈线性标度关系。我们还利用基于线性稳定性分析的简化模型计算了线性阈值估计值,发现其与三维非线性DNS结果吻合良好。

英文摘要:

We study the saturation of three-dimensional unstable perturbations on a fast rotating turbulent flow using direct numerical simulations (DNSs). Under the effect of Kolmogorov forcing, a transition between states dominated by coherent two-dimensional modes to states with three-dimensional variations (quasi-two-dimensional) is observed as we change the global rotation rate. We find this akin to a critical phenomenon, wherein the order parameter scales with the distance to the critical point raised to an exponent. The exponent itself deviates from the predicted mean field value. Also, the nature of the fluctuations of the order parameter near the critical point indicate the presence of on-off intermittency. The critical rotation rate at which the transition occurs exhibits a linear scaling behaviour with the forcing wave number. A reduced model based on linear stability analysis is used to find the linear threshold estimates; we find these to be in good agreement with the 3D nonlinear DNS results.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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