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In this paper, a unified gas-kinetic scheme (UGKS) with simplified multi-scale numerical flux is proposed for the thermodynamic non-equilibrium flow simulation involving the excitation of molecular vibrational degrees of freedom in all flow…

Fluid Dynamics · Physics 2023-02-08 Rui Zhang , Sha Liu , Chengwen Zhong , Congshan Zhuo

We present a semi-analytic model for the interstellar medium that considers local processes and structures of turbulent star-forming gas. A volume element of the interstellar medium is described as a multiphase system, comprising a cold and…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 Harald Braun , Wolfram Schmidt

In this paper we explore a possibility that all transport turbulent models are contained in a coarse-grained kinetic equation. Building on a recent work by H.Chen et al (2004), we account for fluctuations of a single -point probability…

Cellular Automata and Lattice Gases · Physics 2007-07-05 Victor Yakhot

Advances in instrumentation have recently extended detailed measurements of gas kinematics to large samples of high-redshift galaxies. Relative to most nearby, thin disk galaxies, in which gas rotation accurately traces the gravitational…

Our understanding of stellar structure and evolution coming from one-dimensional (1D) stellar models is limited by uncertainties related to multi-dimensional processes taking place in stellar interiors. 1D models, however, can now be tested…

Solar and Stellar Astrophysics · Physics 2022-08-17 F. Rizzuti , R. Hirschi , C. Georgy , W. D. Arnett , C. Meakin , A. StJ. Murphy

In this study we explore the complex multi-phase gas of the circumgalactic medium (CGM) surrounding galaxies. We propose and implement a novel, super-Lagrangian 'CGM zoom' scheme in the moving-mesh code AREPO, which focuses more resolution…

Astrophysics of Galaxies · Physics 2018-12-26 Joshua Suresh , Dylan Nelson , Shy Genel , Kate Rubin , Lars Hernquist

We present a method for modelling star-forming clouds that combines two different models of the thermal evolution of the interstellar medium (ISM). In the combined model, where the densities are low enough that at least some part of the…

Solar and Stellar Astrophysics · Physics 2015-03-19 Matthew R. Bate , Eric R. Keto

Galactic dynamo models take as input certain parameters of the interstellar turbulence, most essentially the correlation time $\tau$, root-mean-square turbulent speed $u$, and correlation scale $l$. However, these quantities are difficult,…

Astrophysics of Galaxies · Physics 2020-08-18 Luke Chamandy , Anvar Shukurov

This study presents an efficient and accurate discrete adjoint gas-kinetic scheme (GKS) for sensitivity analysis and aerodynamic shape optimization in continuum flow regimes. Developed using the backward mode of algorithmic differentiation…

Fluid Dynamics · Physics 2026-04-17 Hangkong Wu , Yuze Zhu , Yajun Zhu , Kun Xu

Simplified, one-dimensional models are necessary to model convection in the context of stellar evolution. By including the non-local effects of convection, turbulent convection models describe convection in a more physical way compared to…

Solar and Stellar Astrophysics · Physics 2026-05-20 T. A. M. Braun , F. Ahlborn , F. Kupka , A. Weiss

Interstellar gas clouds are often both highly magnetized and supersonically turbulent, with velocity dispersions set by a competition between driving and dissipation. This balance has been studied extensively in the context of gases with…

Astrophysics of Galaxies · Physics 2018-01-19 Yuval Birnboim , Christoph Federrath , Mark Krumholz

We analyze the transport properties of a low density ensemble of identical macroscopic particles immersed in an active fluid. The particles are modeled as inelastic hard spheres (granular gas). The non-homogeneous active fluid is modeled by…

Soft Condensed Matter · Physics 2017-10-17 Francisco Vega Reyes , Antonio Lasanta

This paper describes the first steps of development of a new multidimensional time implicit code devoted to the study of hydrodynamical processes in stellar interiors. The code solves the hydrodynamical equations in spherical geometry and…

Instrumentation and Methods for Astrophysics · Physics 2015-05-27 M. Viallet , I. Baraffe , R. Walder

The ISM is a turbulent, multi-phase, and multi-scale medium following scaling relations. Analytical models of galactic gaseous disks need to take into account the multi-scale and multi-phase nature of the interstellar medium. They can be…

Astrophysics of Galaxies · Physics 2022-07-27 T. Lizée , B. Vollmer , J. Braine , P. Gratier , F. Bigiel

We perform Large eddy simulations of turbulent compressible convection in stellar-type convection zones by solving the Navi\'{e}r-Stokes equations in three dimensions. We estimate the extent of penetration into the stable layer above a…

Astrophysics · Physics 2009-06-23 Partha S. Pal , Harinder P. Singh , Kwing L. Chan , M. P. Srivastava

To develop a more convenient subgrid-scale (SGS) model that performs well even in coarse grid cases, we investigate the transport and modeling of SGS turbulent kinetic energy (hereafter SGS energy) in turbulent channel flows based on the…

Fluid Dynamics · Physics 2024-06-12 Kazuhiro Inagaki , Hiromichi Kobayashi

The effects of turbulent dynamic range on scalar mixing in stably stratified turbulence are investigated by an adaptation of the theoretical passive scalar modelling arguments of Beguier et al. (1978) and demonstrated statistically using…

Fluid Dynamics · Physics 2022-04-05 G. D. Portwood , S. M. de Bruyn Kops , C. P. Caulfield

In recent works we developed a model of balanced gas flow where the momentum equation possesses an additional mean field forcing term, which originates from the hard sphere interaction potential between the gas particles. We demonstrated…

Fluid Dynamics · Physics 2021-10-20 Rafail V. Abramov

Turbulent motions in the circumgalactic medium (CGM) play a critical role in regulating the evolution of galaxies, yet their detailed characterization remains elusive. Using two-dimensional velocity maps constructed from spatially-extended…

{We study in some details the statistical properties of the turbulent 2-phase interstellar atomic gas.{We present high resolution bidimensional numerical simulations of the interstellar atomic hydrogen which describe it over 3 to 4 orders…

Astrophysics · Physics 2015-06-24 P. Hennebelle , E. Audit
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