论文标题
衰减磁流失动力湍流的参数研究
Parameter study of decaying magnetohydrodynamic turbulence
论文作者
论文摘要
众所周知，螺旋磁流失动力学（MHD）湍流表现出磁能从小到大尺度的反向转移，这与磁性螺旋性的近似保护有关。最近，一些数值研究注意到非螺旋MHD流也存在反向能量转移。我们运行一组完全分辨的直接数值模拟，并对逆能传递和螺旋和非螺旋MHD的衰减定律进行广泛的参数研究。我们的数值结果显示，随着PRANDTL数量的增加（PM），能量的较小反向转移。后一种特征可能会对宇宙磁场演化产生有趣的后果。此外，我们发现腐烂的法律$ e \ sim t^{ - p} $独立于比例分离，并且仅取决于PM和RE。在螺旋情况下，我们测量$ p_b \ \约0.6 + 14/re $的依赖性。我们还对结果和以前的文献进行了比较，并讨论了观察到的分歧的可能原因
It is well known that helical magnetohydrodynamic (MHD) turbulence exhibits an inverse transfer of magnetic energy from small to large scales, which is related to the approximate conservation of magnetic helicity. Recently, several numerical investigations noticed the existence of an inverse energy transfer also in nonhelical MHD flows. We run a set of fully resolved direct numerical simulations and perform a wide parameter study of the inverse energy transfer and the decaying laws of helical and nonhelical MHD. Our numerical results show only a small inverse transfer of energy that grows as with increasing Prandtl number (Pm). This latter feature may have interesting consequences for cosmic magnetic field evolution. Additionally, we find that the decaying laws $E \sim t^{-p}$ are independent of the scale separation and depend solely on Pm and Re. In the helical case we measure a dependence of the form $p_b \approx 0.6 + 14/Re$. We also make a comparison between our results and previous literature and discuss the possible reason for the observed disagreements
