Effects of Multiplescale Driving on Turbulence Statistics
Abstract
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 energyinjection scales, the process of energy cascade and turbulence dynamo will be different compared with the case of the single energyinjection scale. In this work, we perform threedimensional incompressible/compressible magnetohydrodynamic turbulence simulations. We drive turbulence in Fourier space in two wavenumber ranges, 2 \le k \le \sqrt{1}2 (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 twoscale energy injections and we discuss the observational implications. In the case epsilon_{ L } < epsilon_{ S }, where epsilon_{ L } and epsilon_{ S } are energyinjection rates at the large and small scales, respectively, our results show that even a tiny amount of largescale energy injection can significantly change the properties of turbulence. On the other hand, when epsilon_{ L } >~ epsilon_{ S }, the smallscale driving does not influence the turbulence statistics much unless epsilon_{ L } ~ epsilon_{ S }.
 Publication:

The Astrophysical Journal
 Pub Date:
 January 2014
 DOI:
 10.1088/0004637X/780/1/99
 arXiv:
 arXiv:1312.6129
 Bibcode:
 2014ApJ...780...99Y
 Keywords:

 galaxies: clusters: intracluster medium;
 ISM: general;
 magnetohydrodynamics: MHD;
 turbulence;
 Astrophysics  Astrophysics of Galaxies;
 Astrophysics  Solar and Stellar Astrophysics
 EPrint:
 17 pages, 6 figures