EFFECTS OF MULTIPLE-SCALE DRIVING ON TURBULENCE STATISTICS
EFFECTS OF MULTIPLE-SCALE DRIVING ON TURBULENCE STATISTICS
复制标题
多尺度驱动对湍流统计的影响
DOI：
10.1088/0004-637x/780/1/99
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
Jungyeon Cho
中科院分区：
文献类型：
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作者：
H. Yoo;Jungyeon Cho
湍流在星际介质和团内介质等天体物理流体中普遍存在。在湍流研究中，通常假设流体在单一尺度上被驱动。然而，在天体物理流体中，可能有许多不同的驱动机制作用于不同的尺度。如果存在多个能量注入尺度，能量级联和湍流发电机的过程将与单一能量注入尺度的情况不同。在这项工作中，我们进行三维不可压缩/可压缩磁流体动力学湍流模拟。我们在两个波数范围内（大尺度）和15 k 26（小尺度）驱动傅立叶空间中的湍流。我们通过改变区域内强迫的幅度，在每个区域内注入不同的能量。我们提出的动能和磁能密度的时间演化，并讨论在两个尺度的能量注入的存在下的湍流发电机。我们展示了如何动力学，磁和密度谱的影响，由两个尺度的能量注入，我们讨论了观测的影响。在α L <α S的情况下，其中α L和α S分别是大尺度和小尺度的能量注入率，我们的结果表明，即使是少量的大尺度能量注入也可以显着改变湍流的性质。另一方面，当湍流扰动时，小尺度驱动对湍流统计的影响不大，除非湍流扰动。
Turbulence is ubiquitous in astrophysical fluids such as the interstellar medium and the intracluster medium. In turbulence studies, it is customary to assume that fluid is driven on a single scale. However, in astrophysical fluids, there can be many different driving mechanisms that act on different scales. If there are multiple energy-injection scales, the process of energy cascade and turbulence dynamo will be different compared with the case of the single energy-injection scale. In this work, we perform three-dimensional incompressible/compressible magnetohydrodynamic turbulence simulations. We drive turbulence in Fourier space in two wavenumber ranges, (large scale) and 15 ≲ k ≲ 26 (small scale). We inject different amount of energy in each range by changing the amplitude of forcing in the range. We present the time evolution of the kinetic and magnetic energy densities and discuss the turbulence dynamo in the presence of energy injections at two scales. We show how kinetic, magnetic, and density spectra are affected by the two-scale energy injections and we discuss the observational implications. In the case ϵL < ϵS, where ϵL and ϵS are energy-injection rates at the large and small scales, respectively, our results show that even a tiny amount of large-scale energy injection can significantly change the properties of turbulence. On the other hand, when ϵL ≳ ϵS, the small-scale driving does not influence the turbulence statistics much unless ϵL ∼ ϵS.
DOI：
10.1086/591228
发表时间：
2008-06
期刊：
The Astrophysical Journal
影响因子：
--
作者：
E. Scannapieco;M. Brüggen
通讯作者：
E. Scannapieco;M. Brüggen