Strong magnetohydrodynamic turbulence with cross helicity
Strong magnetohydrodynamic turbulence with cross helicity
复制标题
具有交叉螺旋性的强磁流体动力湍流
DOI：
10.1063/1.3396370
复制
发表时间：
2009
影响因子：
2.2
通讯作者：
S. Boldyrev
中科院分区：
文献类型：
--
作者：
J. C. Perez;S. Boldyrev
磁流体动力学(MHD)为各种天体物理和实验室系统中的磁等离子体湍流提供了最简单的描述。具有非零交叉螺旋度的MHD湍流通常被称为不平衡，因为它意味着Alfven涨落平行和反平行于背景场传播的能量不相等。最近的分析和数值研究表明，在每个尺度上，MHD湍流都由正的和负的交叉螺旋度区域组成，这表明这种湍流本质上是局部不平衡的。本文给出了有交叉螺旋度和无交叉螺旋度的定常不可压缩MHD湍流的高分辨率数值模拟结果。本文认为，沿相反方向运动的涨落能谱(E±)的惯性标度与交叉螺旋度大小无关。当交叉螺旋度非零时，E+和E−保持相同的比例，但具有不同的幅度，取决于交叉螺旋度的大小。
Magnetohydrodynamics (MHD) provides the simplest description of magnetic plasma turbulence in a variety of astrophysical and laboratory systems. MHD turbulence with nonzero cross helicity is often called imbalanced, as it implies that the energies of Alfven fluctuations propagating parallel and antiparallel the background field are not equal. Recent analytical and numerical studies have revealed that at every scale, MHD turbulence consists of regions of positive and negative cross helicity, indicating that such turbulence is inherently locally imbalanced. In this paper, results from high resolution numerical simulations of steady-state incompressible MHD turbulence, with and without cross helicity are presented. It is argued that the inertial range scaling of the energy spectra (E±) of fluctuations moving in opposite directions is independent of the amount of cross helicity. When cross helicity is nonzero, E+ and E− maintain the same scaling, but have differing amplitudes depending on the amount of cross ...