磁流体动力学turbulence中三维到二维的转变
Tridimensional to bidimensional transition in magnetohydrodynamic turbulence with a guide field and kinetic helicity injection
摘要：
我们研究的三维磁流体力学流动的尺寸只强制机械，当磁引导场的强度逐渐增加的过渡。我们使用数值模拟来考虑机械强迫注入（或不注入）的流动中的螺旋度的情况。随着引导场的增加，磁场波动的强度按照引导场强度的幂律减小。我们表明，足够强的引导场，螺旋磁流体动力学流可以成为几乎二维的。在这种情况下，机械能可以经历与逆级联相容的过程，优先向大于强迫尺度的尺度转移。螺旋度的存在改变了小磁场波动的谱标度，并影响速度场和速度梯度的统计。此外，在小尺度下，流动的动力学变得由螺旋度的直接级联主导，这可以用来推导速度场的标度律。
英文摘要：
We study the transition in dimensionality of a three-dimensional magnetohydrodynamic flow forced only mechanically, when the strength of a magnetic guiding field is gradually increased. We use numerical simulations to consider cases in which the mechanical forcing injects (or not) helicity in the flow. As the guiding field is increased, the strength of the magnetic field fluctuations decrease as a power law of the guiding field intensity. We show that for strong enough guiding fields, the helical magnetohydrodynamic flow can become almost two-dimensional. In this case, the mechanical energy can undergo a process compatible with an inverse cascade, being transferred preferentially towards scales larger than the forcing scale. The presence of helicity changes the spectral scaling of the small magnetic field fluctuations, and affects the statistics of the velocity field and of the velocity gradients. Moreover, at small scales the dynamics of the flow becomes dominated by a direct cascade of helicity, which can be used to derive scaling laws for the velocity field.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
