The shock waves in decaying supersonic turbulence

Smith, M.D. and Mac Low, M.-M. and Zuev, J.M. (2000) The shock waves in decaying supersonic turbulence. Astronomy and Astrophysics, 356 (1). pp. 287-300. ISSN 0004-6361. (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided)

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Abstract

We here analyse numerical simulations of supersonic, hypersonic and magnetohydrodynamic turbulence that is free to decay. Our goals are to understand the dynamics of the decay and the characteristic properties of the shock waves produced. This will be useful for interpretation of observations of both motions in molecular clouds and sources of non-thermal radiation. We find that decaying hypersonic turbulence possesses an exponential tail of fast shocks and an exponential decay in time, i.e. the number of shocks is proportional to t exp(-ktv) for shock velocity jump v and mean initial wavenumber k. In contrast to the velocity gradients, the velocity Probability Distribution Function remains Gaussian with a more complex decay law. The energy is dissipated not by fast shocks but by a large number of low Mach number shocks. The power loss peaks near a low-speed turn-over in an exponential distribution. An analytical extension of the mapping closure technique is able to predict the basic decay features. Our analytic description of the distribution of shock strengths should prove useful for direct modeling of observable emission. We note that an exponential distribution of shocks such as we find will, in general, generate very low excitation shock signatures.

Item Type: Article
Uncontrolled keywords: Hydrodynamics, ISM: clouds, ISM: kinematics and dynamics, Shock waves, Turbulence
Subjects: Q Science > QB Astronomy > QB460 Astrophysics
Divisions: Faculties > Sciences > School of Physical Sciences > Centre for Astrophysics and Planetary Sciences
Depositing User: Giles Tarver
Date Deposited: 11 Aug 2015 10:16 UTC
Last Modified: 12 Aug 2015 16:11 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/50136 (The current URI for this page, for reference purposes)
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