Can the thermal instability drive turbulence?

Abstract

The thermal instability with a piecewise power law cooling function is investigated using one- and three-dimensional simulations with periodic and shearing-periodic boundary conditions in the presence of constant thermal diffusion and kinematic viscosity coefficients. Consistent with earlier findings, the flow behavior depends on the average density, <rho>. When $⟨\rho |$ is in the range 1-5 x 10^{-24} g cm^{-3} the system is unstable and segregates into cool and warm phases with temperatures of roughly 100 and 10^4 K, respectively. However, in all cases the resulting average pressure <p> is independent of <rho> and just a little above the minimum value. For a constant heating rate of 0.015 erg g^{-1} s^{-1}, the mean pressure is around 24 x 10^{-14} dyn (corresponding to p/k_B ~ K cm^{-3}). Cool patches tend to coalesce into bigger ones. In all cases investigated there is no sustained turbulence, which is in agreement with earlier results. Simulations in which turbulence is driven by a body force show that when rms velocities of between 10 and 30 km/s are obtained, the resulting dissipation rates rates are comparable to the thermal energy input rate. The resulting mean pressures are then about 30 x 10^{-14} dyn, corresponding to p/k_B ~ 2170 K cm^{-3}. This is comparable to the value expected for the Galaxy. Differential rotation tends to make the flow two-dimensional, that is, uniform in the streamwise direction, but this does not lead to instability.

10 pages, 13 figures

References in corpus (20)

• The Neutral Atomic Phases of the ISM in the Galaxy
• Nonlinear Outcome of Gravitational Instability in Cooling, Gaseous Disks
• Kinetic Energy Decay Rates of Supersonic and Super-Alfvenic Turbulence in Star-Forming Clouds
• An Origin of Supersonic Motions in Interstellar Clouds
• Thermal condensation in a turbulent atomic hydrogen flow
• Hydromagnetic turbulence in computer simulations
• The Distribution of Thermal Pressures in the Interstellar Medium from a Survey of C I Fine-Structure Excitation
• Thermal Instability-Induced Interstellar Turbulence
• The Distribution of Pressures in a Supernova-Driven Interstellar Medium. I. Magnetized Medium
• Is Thermal Instability Significant in Turbulent Galactic Gas?
• The Field Condition: A New Constraint of Spatial Resolution in Simulations of the nonlinear Development of Thermal Instability
• Formation of Cavities, Filaments, and Clumps by the Non-linear Development of Thermal and Gravitational Instabilities in the Interstellar Medium under Stellar Feedback
• Thermal and Magnetorotational Instability in the ISM: Two-Dimensional Numerical Simulations
• Saturated-State Turbulence and Structure from Thermal and Magnetorotational Instability in the ISM: Three-Dimensional Numerical Simulations
• Inertial range scaling in numerical turbulence with hyperviscosity
• The nonlinear development of the thermal instability in the atomic ISM and its interaction with random fluctuations
• The pressure distribution in thermally bistable turbulent flows
• How Long can Left and Right Handed Life Forms Coexist?
• Scaling Relations for Turbulence in the Multiphase Interstellar Medium
• Interstellar Phase Transitions Stimulated by Time-dependent Heating

Cited by in corpus (16)

• Astrophysical turbulence modeling
• Non-isobaric Thermal Instability
• Dynamo coefficients from local simulations of the turbulent ISM
• The turbulent fragmentation of the interstellar medium: The impact of metallicity on global star formation
• Turbulence in the Intergalactic Medium
• The small-scale dynamo in a multiphase supernova-driven medium
• Clustering and dynamic decoupling of dust grains in turbulent molecular clouds
• The Effect of Anisotropic Conduction on the Thermal Instability in the Interstellar Medium
• Isentropic thermal instability in atomic surface layers of photodissociation regions
• Exploring cloudy gas accretion as a source of interstellar turbulence in the outskirts of disks
• Self-Sustained Turbulence without Dynamical Forcing: A Two-Dimensional Study of a Bistable Interstellar Medium
• Batchelor, Saffman, and Kazantsev spectra in galactic small-scale dynamos
• A Field-length based refinement criterion for adaptive mesh simulations of the interstellar medium
• On The Fine Tuning and Physical Origin of Line-Locked Absorption Systems in Active Galaxies
• Angular Momentum Transport in Extended Galactic Disks
• Mean fields and fluctuations in compressible magnetohydrodynamic flows