Mininni P D, Pouquet A
Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and CONICET, Ciudad Universitaria, 1428 Buenos Aires, Argentina.
Phys Rev E Stat Nonlin Soft Matter Phys. 2009 Aug;80(2 Pt 2):025401. doi: 10.1103/PhysRevE.80.025401. Epub 2009 Aug 3.
We present an analysis of data stemming from numerical simulations of decaying magnetohydrodynamic (MHD) turbulence up to grid resolution of 1536(3) points and up to Taylor Reynolds number of approximately 1200 . The initial conditions are such that the initial velocity and magnetic fields are helical and in equipartition, while their correlation is negligible. Analyzing the data at the peak of dissipation, we show that the dissipation in MHD seems to asymptote to a constant as the Reynolds number increases, thereby strengthening the possibility of fast reconnection events in the solar environment for very large Reynolds numbers. Furthermore, intermittency of MHD flows, as determined by the spectrum of anomalous exponents of structure functions of the velocity and the magnetic field, is stronger than that of fluids, confirming earlier results; however, we also find that there is a measurable difference between the exponents of the velocity and those of the magnetic field, reminiscent of recent solar wind observations. Finally, we discuss the spectral scaling laws that arise in this flow.
我们对源于衰减磁流体动力学（MHD）湍流数值模拟的数据进行了分析，模拟的网格分辨率高达1536(3)个点，泰勒雷诺数约为1200。初始条件设定为初始速度和磁场呈螺旋状且处于能量均分状态，而它们之间的相关性可忽略不计。通过分析耗散峰值处的数据，我们发现随着雷诺数增加，MHD中的耗散似乎渐近于一个常数，从而增强了在非常大的雷诺数情况下太阳环境中快速重联事件发生的可能性。此外，由速度和磁场结构函数的反常指数谱所确定的MHD流的间歇性比流体更强，这证实了早期的结果；然而，我们还发现速度指数和磁场指数之间存在可测量的差异，这让人联想到近期太阳风的观测结果。最后，我们讨论了这种流动中出现的谱标度律。
