The turbulent destruction of clouds - I. A k-epsilon treatment of turbulence in 2D models of adiabatic shock-cloud interactions

Abstract

The interaction of a shock with a cloud has been extensively studied in the literature, where the effects of magnetic fields, radiative cooling and thermal conduction have been considered. However, the formation of fully developed turbulence has often been prevented by the artificial viscosity inherent in hydrodynamical simulations, and a uniform post-shock flow has been assumed in all previous single-cloud studies. In reality, the flow behind the shock is also likely to be turbulent, with non-uniform density, pressure and velocity structure created as the shock sweeps over inhomogenities upstream of the cloud. To address these twin issues we use a sub-grid compressible k-epsilon turbulence model to estimate the properties of the turbulence generated in shock-cloud interactions and the resulting increase in the transport coefficients that the turbulence brings. A detailed comparison with the output from an inviscid hydrodynamical code puts these new results into context. We find that cloud destruction in inviscid and k-epsilon models occurs at roughly the same speed when the post-shock flow is smooth and when the density contrast between the cloud and inter-cloud medium is less than 100. However, there are increasing and significant differences as this contrast increases. Clouds subjected to strong ``buffeting'' by a highly turbulent post-shock environment are destroyed significantly quicker. Additional calculations with an inviscid code where the post-shock flow is given random, grid-scale, motions confirms the more rapid destruction of the cloud. Our results clearly show that turbulence plays an important role in shock-cloud interactions, and that environmental turbulence adds a new dimension to the parameter space which has hitherto been studied (abridged).

31 pages, 22 figures, accepted for publication in MNRAS

References in corpus (14)

• Interactions of a Light Hypersonic Jet with a Non-Uniform Interstellar Medium
• The importance of magnetic-field-oriented thermal conduction in the interaction of SNR shocks with interstellar clouds
• The Magnetohydrodynamics of Shock-Cloud Interaction in Three Dimensions
• Gemini GMOS/IFU spectroscopy of NGC 1569 - I: Mapping the properties of a young star cluster and its environment
• Infrared Observations of The Helix Planetary Nebula
• A Clumping Independent Diagnostic of Stellar Mass-loss Rates: Rapid Clump Destruction in Adiabatic Colliding Winds
• HST/STIS spectroscopy of the environment in the starburst core of M82
• Hydrodynamical adaptive mesh refinement simulations of turbulent flows - I. Substructure in a wind
• Shock-triggered formation of magnetically-dominated clouds
• VLT / Infrared Integral Field Spectrometer Observations of Molecular Hydrogen Lines in the Knots in the Planetary Nebula NGC 7293 (the Helix Nebula)
• Shock-cloud interaction in the Vela SNR II. Hydrodynamic model
• The tails in the Helix Nebula NGC 7293
• The Interaction Between a Pulsed Astrophysical Jet and Small-Scale Heterogeneous Media
• The generation of optical emission-line filaments in galaxy clusters