论文标题
可压缩的二维湍流：级联反转和对强加磁场的敏感性
Compressible two-dimensional turbulence: cascade reversal and sensitivity to imposed magnetic field
论文作者
论文摘要
我们研究可压缩性对二维湍流的影响，例如那些对天体物理磁盘进行建模的影响。我们证明，随着马赫数MA的增加，级联反应的方向从零ma逆到无限MA的直线。因此，按照先前的数据一致，在阶数的MA上，从泵的规模到大小的大小。对于具有较大MA的超音速湍流，级联反应是直接的，如三个维度，从而导致多重构成密度场。对于可压缩流体的可压缩流，施加的外部磁场允许操纵流量，即使在小马赫数下也可能会产生较大的变化。因此，必须谨慎使用Zeldovich Antidynamo定理（在零MA下，磁场在稳态下为零。真实流量具有有限的MA，并且对于穿过磁盘的大型磁通量多么小，磁场会显着改变流量，或者完全重新安排它。对于与天体物理磁盘相关的大型MA，与基于平均场的估计值相比，磁场能量的增强。我们建议使用二维汉堡的湍流，其三维对应物用于研究宇宙的大规模结构，作为超音速薄积分磁盘的模型。
We study the impact of compressibility on two-dimensional turbulent flows, such as those modeling astrophysical disks. We demonstrate that the direction of cascade undergoes continuous transition as the Mach number Ma increases, from inverse at zero Ma, to direct at infinite Ma. Thus, at Ma of order one comparable amounts of energy flow from the scale of the pumping to large and small scales, in accord with previous data. For supersonic turbulence with large Ma, the cascade is direct, as in three dimensions, which results in multifractal density field. For compressible flows of conducting fluids, imposing external magnetic field allows to manipulate the flow producing possibly large changes even at small Mach number. Thus Zeldovich antidynamo theorem, by which at zero Ma the magnetic field is zero in the steady state, must be used with caution. Real flows have finite Ma and, however small it is, for large magnetic flux through the disk, the magnetic field changes the flow appreciably, or rearranges it completely. For large Ma, relevant for astrophysical disks, the magnetic field energy is enhanced by a large factor as compared to estimates based on the mean field. We propose to use two-dimensional Burgers turbulence, whose three-dimensional counterpart is used for studies of the large-scale structure of the Universe, as a model for supersonic thin accretion disks.
