CASCADE MODELS FOR MAGNETOHYDRODYNAMIC TURBULENCE
CASCADE MODELS FOR MAGNETOHYDRODYNAMIC TURBULENCE
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DOI：
10.1103/physreve.50.2702
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发表时间：
1994-10-01
影响因子：
2.4
通讯作者：
BISKAMP, D
中科院分区：
文献类型：
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作者：
BISKAMP, D
本文研究了Gloaguen et al.[物理学报，17,154(1985)]的复杂级联模型。第一部分忽略了阿尔文效应。讨论了固定解。对于纯动力学湍流，观察到k空间中的相干结构现象。对于一般的磁流体动力学湍流，能谱一般接近于k(-5/3)，惯性范围统计量，特别是结构函数，与在流体动力学（流体）湍流中观察到的相似。第二部分包括Alfven效应。对于最简单的恒定大尺度场B-0，能谱为k(-1.25)，比预期的Iroshnikov-Kraichnan定律k（-3/2）平坦，且惯性范围统计量完全为高斯分布。因此，必须对模型进行改进。假设B-0为实际波动场，则重新引入间歇性，频谱接近k(-3/2)，尽管在高k时趋于平坦，因此可能不存在一致有效的惯性范围幂律谱。
The complex cascade model by Gloaguen et al. [Physica D 17, 154 (1985)] for magnetohydrodynamic turbulence is studied. In the first part the Alfven effect is neglected. Stationary solutions are discussed. For purely kinetic turbulence a phenomenon, coherent structures in k spaces, is observed. For general magnetohydrodynamic turbulence, energy spectra are, in general, close to k(-5/3), and inertial-range statistics, in particular structure functions, are similar to those observed in hydrodynamic (fluid) turbulence. In the second part the Alfven effect is included. For the simplest case of a constant large-scale field B-0, energy spectra are k(-1.25), flatter than the expected Iroshnikov-Kraichnan law k(-3/2), and the inertial-range statistics are exactly Gaussian. Hence, the model has to be refined. Assuming B-0 to be the actual fluctuating field, intermittency is reintroduced, and the spectrum is close to k(-3/2), though it tends to become flatter for high k, such that a uniformly valid inertial-range power-law spectrum may not exist.