Turbulence characteristics, energy equipartition, and zonal flow generation in coupled drift wave-parallel velocity gradient driven turbulence
Turbulence characteristics, energy equipartition, and zonal flow generation in coupled drift wave-parallel velocity gradient driven turbulence
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DOI：
10.1088/1361-6587/ab0f0c
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发表时间：
2019-04
影响因子：
2.2
通讯作者：
T. T. Tran-T.;S. S. Kim-S.;H. Jhang;Juhyung Kim
中科院分区：
文献类型：
--
作者：
T. T. Tran-T.;S. S. Kim-S.;H. Jhang;Juhyung Kim
本文对漂移波（DW）-平行速度梯度（PVG）耦合驱动的湍流特性进行了数值研究。三维Hasegawa-Mima方程结合离子平行流动力学用于这项研究。能量分析，分析和计算，显示能量均分的平行雷诺功率（即自由能，由于在平衡平行速度梯度）在平行和垂直方向。相当大一部分的垂直能量是通过平行耦合转移产生的垂直带状流（ZF），这意味着增加的ZF水平时，存在一个平衡PVG。平行-垂直耦合动力学的仔细分析表明，在这个系统中的涡拉伸项在ZF的产生中起着重要的作用。这与中性流体湍流相反，中性流体湍流阻碍逆叶栅过程。然而，与DW湍流相比，PVG湍流的ZF生成被发现是不太有效的。
We perform a computational study of characteristics of coupled drift wave (DW)-parallel velocity gradient (PVG) driven turbulence. The three-dimensional Hasegawa–Mima equation combined with ion parallel flow dynamics is used for this study. Energetic analyses, both analytic and computational, show the energy equipartition of the parallel Reynolds power (i.e. the free energy due to a gradient in equilibrium parallel velocity) in parallel and perpendicular directions. A considerable portion of the perpendicular energy that is transferred through the parallel coupling generates the perpendicular zonal flow (ZF), implying the increase of the ZF level when an equilibrium PVG is present. A careful analysis of parallel-perpendicular coupling dynamics shows that the vortex stretching-like term in this system plays a significant role in the ZF generation. This is in contrast to the neutral fluid turbulence where it hinders the inverse cascade process. However, the ZF generation from PVG turbulence is found to be less effective in comparison with that of DW turbulence.