Interstellar medium by, for example, collimated or spherical outflows or supernovaĮxplosions ( Li & Nakamura 2006 de Avillez & Breitschwerdt 2007 Wang et al. Or occasional energy input at randomly selected grid cells, to mimic energy input into the Typical ways of forcing are continuous energy input in each grid cell Turbulence in such simulations is either left 2010 Gazol & Kim 2010 Price et al.Ģ011 Seifried et al. Mac Low 1999 Padoan & Nordlund 1999 Boldyrev et al.Ģ002b, a Kritsuk & Norman 2004 Padoan et al.Ģ004 Kritsuk et al. Of physics from pure isothermal hydrodynamics to the inclusion of magnetic fields, radiativeĬooling, self-gravity, chemistry, or relativistic flows ( Stone et al. These simulations meanwhile cover an impressive range Substantial progress in understanding supersonic turbulence and its characteristics hasĬome from 3D periodic box simulations. Present paper stresses the combined view, the interplay between large scale aspects of theĬollision zone, and the characteristics of the turbulence in its interior. Recent years, on their large scale properties as well as on the turbulence they harbor. In the context of molecular clouds and star formation stimulated extensive research in The idea that such zones may also play a crucial role 2000 Fan & WeiĢ004), or galaxy formation and cosmology ( AnninosĪgertz et al. 1992 Myasnikov & Zhekov 1998 Parkin & Pittard 2010), the jets of high-energy objects ( Panaitescu et al. They occur, for example, inīinary star systems ( Stevens et al. Shock-bound interaction zones are ubiquitous in astrophysics. Key words: shock waves / turbulence / hydrodynamics / ISM: kinematics and dynamics / gamma-ray burst: general / binaries: close Robustness of our findings toward more realistic setups remains to be tested. That even a simple model setup results in a richly structured interaction zone. Interpreting turbulence characteristics derived from observations. We suggest that this should be kept in mind when Turbulence characteristics generallyĭeviate markedly from those found for uniformly driven, supersonic, isothermal turbulence Perpendicular or parallel to the upstream flow. Structure functions differ depending on whether they are computed along a line-of-sight Like the density variance – Mach number relation. The anisotropy carries over to other quantities Uniform, head-on colliding flows generally disfavor turbulence that is at the same time It is also anisotropic: transverse to the upstream flows The turbulence is inhomogeneous, weaker in the center of the zone thanĬlose to the confining shocks. The root mean square Mach number isĭeviations toward weaker turbulence are found as the collision zone thickens and for small The fraction of energy dissipated at theĬonfining shocks decreases with increasing M u. Modulation grows with the collision zone. Results are in line with expectations from self-similarity arguments. Is partly dissipated and spatially modulated by the shocks confining the zone. The turbulence in the collision zone is driven by the upstream flows, whose kinetic energy Homogeneous flows with identical upstream (subscript u) flow parameters and Mach numbers Our model setup is as simpleĪs can be: 3D hydrodynamical simulations of two head-on colliding, isothermal, and Shed light on the interplay between large scale aspects of such collision zones and theĬharacteristics of the compressible turbulence they harbor. Associatedįlow collisions shape observable properties and internal physics alike. Large scale supersonic bulk flows are present in a wide range of astrophysical objects,įrom O-star winds to molecular clouds, galactic sheets, accretion, or γ-ray bursts. Lyon Cedex National Supercomputing Center, CSCS Lugano, École Normale Supérieure, Lyon, CRAL, UMR CNRS 5574, Université de Astronomical objects: linking to databasesĭoris Folini 1, Rolf Walder 1 and Jean M.Including author names using non-Roman alphabets.Suggested resources for more tips on language editing in the sciences Punctuation and style concerns regarding equations, figures, tables, and footnotes
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