Two-dimensional AMR simulations of colliding flows

Abstract

Colliding flows are a commonly used scenario for the formation of molecular clouds in numerical simulations. Due to the thermal instability of the warm neutral medium, turbulence is produced by cooling. We carry out a two-dimensional numerical study of such colliding flows in order to test whether statistical properties inferred from adaptive mesh refinement (AMR) simulations are robust with respect to the applied refinement criteria. We compare probability density functions of various quantities as well as the clump statistics and fractal dimension of the density fields in AMR simulations to a static-grid simulation. The static grid with 2048^2 cells matches the resolution of the most refined subgrids in the AMR simulations. The density statistics is reproduced fairly well by AMR. Refinement criteria based on the cooling time or the turbulence intensity appear to be superior to the standard technique of refinement by overdensity. Nevertheless, substantial differences in the flow structure become apparent. In general, it is difficult to separate numerical effects from genuine physical processes in AMR simulations.

6 pages, 6 figures, submitted to A&A

References in corpus (6)

• Molecular Cloud Evolution II. From cloud formation to the early stages of star formation in decaying conditions
• Numerical simulations of compressively driven interstellar turbulence: I. Isothermal gas
• From the warm magnetized atomic medium to molecular clouds
• The Fractal Density Structure in Supersonic Isothermal Turbulence: Solenoidal versus Compressive Energy Injection
• The Birth of Molecular Clouds: Formation of Atomic Precursors in Colliding Flows
• Protostellar collapse: A comparison between SPH and AMR calculations

Cited by in corpus (5)

• Fragmentation in the First Galaxies
• Self-Convergence of Radiatively Cooling Clumps
• Forced turbulence in thermally bistable gas: A parameter study
• Kiloparsec-Scale Simulations of Star Formation in Disk Galaxies. I. The unmagnetized and zero-feedback limit
• Numerical heat conduction in hydrodynamical models of colliding hypersonic flows