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The extent of mixed regions around convective zones is one of the biggest uncertainties in stellar evolution. 1D overshooting descriptions introduce a free parameter ($f_{ov}$) that is in general not well constrained from observations.…

Solar and Stellar Astrophysics · Physics 2021-03-08 Johann Higl , Ewald Mueller , Achim Weiss

We consider a Leray model with a nonlinear differential low-pass filter for the simulation of incompressible fluid flow at moderately large Reynolds number (in the range of a few thousands) with under-refined meshes. For the implementation…

Numerical Analysis · Mathematics 2024-12-20 Michele Girfoglio , Annalisa Quaini , Gianluigi Rozza

In this paper, we have used the QUICK scheme of the finite volume method to investigate the problem of steady 2-D free convective incompressible flow with heat and mass transfer in an inclined rectangular domain at different Rayleigh…

Fluid Dynamics · Physics 2017-08-28 V. Ambethkar , D. Kushawaha

We present the two-dimensional inflow-outflow solutions of radiation hydrodynamic (RHD) equations of supercritical accretion flows. Compared with prior studies, we include all components of the viscous stress tensor. We assume steady state…

High Energy Astrophysical Phenomena · Physics 2020-01-15 Fatemeh Zahra Zeraatgari , Amin Mosallanezhad , Ye-Fei Yuan , De-Fu Bu , Liquan Mei

We analyse the non-linear, three-dimensional response of a gaseous, viscous protoplanetary disc to the presence of a planet of mass ranging from one Earth mass (1 M$_e$) to one Jupiter mass (1 M$_J$) by using the ZEUS hydrodynamics code. We…

Astrophysics · Physics 2008-11-26 M. R. Bate , S. H. Lubow , G. I. Ogilvie , K. A. Miller

In this paper, we study nonlinear stability of the 3D plane Couette flow $(y,0,0)$ at high Reynolds number ${Re}$ in a finite channel $\mathbb{T}\times [-1,1]\times \mathbb{T}$. It is well known that the plane Couette flow is linearly…

Analysis of PDEs · Mathematics 2020-06-24 Qi Chen , Dongyi Wei , Zhifei Zhang

We present a radiation-hydrodynamics (RHD) scheme that enables 3D simulations resolving both protostellar interiors and their surrounding accretion flows within a single framework, to clarify how a protostar evolves while interacting with…

Solar and Stellar Astrophysics · Physics 2026-02-19 Kazutaka Kimura , Kazuyuki Sugimura , Takashi Hosokawa , Hajime Fukushima , Kazuyuki Omukai

This work studies the effects of a through-flow on two-dimensional electrohydrodynamic (EHD) flows of a dielectric liquid confined between two plane plates, as a model problem to further our understanding of the fluid mechanics in the…

Fluid Dynamics · Physics 2022-02-03 Zhe Feng , Dongdong Wan , Bo-Fu Wang , Mengqi Zhang

(Abridged) We analyse the stability and evolution of power-law accretion disc models. These have midplane densities that follow radial power-laws, and have either temperature or entropy distributions that are power-law functions of…

Earth and Planetary Astrophysics · Physics 2015-06-11 Richard P. Nelson , Oliver Gressel , Orkan M. Umurhan

Supergiant fast X-ray transients (SFXTs) are X-ray binary systems with a supergiant companion and likely a neutron star, which show a fast ($\sim 10^3$ s) and high variability with a dynamic range up to $10^{5-6}$. Given their extreme…

High Energy Astrophysical Phenomena · Physics 2019-11-06 L. Ducci , P. Romano , L. Ji , A. Santangelo

Multiphase flow in porous media underpins subsurface energy and environmental technologies, including geological CO$_2$ storage and underground hydrogen storage, yet pore-scale dynamics in realistic three-dimensional materials remain…

Many astrophysical simulations involve extreme dynamic range of timescales around 'special points' in the domain (e.g. black holes, stars, planets, disks, galaxies, shocks, mixing interfaces), where processes on small scales couple strongly…

Instrumentation and Methods for Astrophysics · Physics 2026-05-11 Philip F. Hopkins , Elias R. Most

A new numerical method is introduced to study the problem of time evolution of generic non-linear dynamical systems in four-dimensional spacetimes. It is assumed that the time level surfaces are foliated by a one-parameter family of…

General Relativity and Quantum Cosmology · Physics 2015-06-05 Peter Csizmadia , Andras Laszlo , Istvan Racz

We investigated the instability of advective accretion flow as a consequence of angular momentum transfer in one-dimensional, quasi-spherical transonic accretion flow around a non-rotating black hole. The code is designed to include the…

Cosmology and Nongalactic Astrophysics · Physics 2011-02-09 Seong-Jae Lee , Dongsu Ryu , Indranil Chattopadhyay

The stability of mass transfer in binaries with convective giant donors remains an open question in modern astrophysics. There is a significant discrepancy between what the existing methods predict for a response to mass loss of the giant…

Solar and Stellar Astrophysics · Physics 2015-06-23 K. Pavlovskii , N. Ivanova

Multicanonical ensemble simulations for the simulation of first-order phase transitions suffer from exponential slowing down. Monte Carlo autocorrelation times diverge exponentially with free energy barriers $\Delta F$, which in $L^d$ boxes…

Statistical Mechanics · Physics 2007-05-23 Thomas Neuhaus , Johannes S. Hager

The paper is devoted to the simulation of maritime two-phase flows of air and water. Emphasis is put on an extension of the classical Volume-of-Fluid (VoF) method by a diffusive contribution derived from a Cahn-Hilliard (CH) model and its…

Computational Physics · Physics 2020-03-24 Niklas Kühl , Michael Hinze , Thomas Rung

In this study, a series of simulations are conducted to investigate the motion of a small cylinder in an expansion tube, focusing on two-dimensional dynamics. These simulations are performed on the FLUENT platform employing the Overset…

Fluid Dynamics · Physics 2024-03-28 Sai Peng , Qiyu Deng , Lin Zhou , Tao Huang , Peng Yu

This paper concerns the Couette flow for 2-D compressible Navier-Stokes equations (N-S) in an infinitely long flat torus $\Torus\times\R$. Compared to the incompressible flow, the compressible Couette flow has a stronger lift-up effect and…

Analysis of PDEs · Mathematics 2024-09-11 Feimin Huang , Rui Li , Lingda Xu

This work studies the hydrodynamics of self-gravitating compressible isothermal fluids. We show that the hydrodynamic evolution equations in absence of viscosity are scale covariant. We study the evolution of the time dependent fluctuations…

Astrophysics · Physics 2009-10-31 B. Semelin , N. Sanchez , H. J. de Vega