The Bulletin of The Korean Astronomical Society (천문학회보)
- Volume 40 Issue 1
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- Pages.58.2-58.2
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- 2015
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- 1226-2692(pISSN)
MHD Turbulence in Expanding and Contracting Media
- Park, Junseong (Dept. of Phisics, Ulsan National Institute of Science and Technology) ;
- Ryu, Dongsu (Dept. of Phisics, Ulsan National Institute of Science and Technology) ;
- Cho, Jungyeon (Dept. of Astronomy and Space Science, Chungnam National University)
- Published : 2015.04.10
Abstract
We investigate the decaying incompressible MHD turbulence by including the effect of the expansion and contraction of background medium. In such an environment, incompressible MHD turbulence has two kinds of time scale. One is the eddy turn-over time (teddy), the other is the expansion/contraction time (texp-cntr). The turbulence is expected to behave differently according to the relationship between the two time scales. For instance, for teddy < texp-cntr, the turbulence would be decay more or less as in a static medium. On the other hand, for teddy > texp-cntr, the effects of expansion and contraction would be dominant. We examine the properties of turbulence in these two regime cases. Based on it, we derive a scaling for the time evolution of flow velocity and magnetic field. (i) In the decay effect dominant case, the velocity and magnetic field scale as
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