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We are re-examining the problem of stellar migration in disc galaxies from a diffusion perspective. We use for the first time the formulation of the diffusion rates introduced by \citet{1979PhR....52..263C}, applied to both energy $E$ and…

Astrophysics of Galaxies · Physics 2019-12-09 Hervé Wozniak

The influence of controlled vibrations on the granular rheology is investigated in a specifically designed experiment. We study experimentally a thin granular film spreading under the action of horizontal vibrations. A nonlinear diffusion…

Soft Condensed Matter · Physics 2009-11-13 Ivan Sanchez , Franck Raynaud , Jose Lanuza , Bruno Andreotti , Eric Clement , Igor S. Aranson

Out-of-equilibrium systems, inherently complex and challenging to understand, are prevalent across various disciplines, including physics where they arise in contexts such as fluid dynamics. In particular, critical out-of-equilibrium…

Statistical Mechanics · Physics 2025-10-14 J. M. Marcos

We develop an analytic theory to describe spiral density waves propagating in a shearing disc in the weakly nonlinear regime. Such waves are generically found to be excited in simulations of turbulent accretion disks, in particular if said…

Earth and Planetary Astrophysics · Physics 2015-05-30 Tobias Heinemann , John C. B. Papaloizou

In this paper we investigate the influence of radiative transport on the growth of the magnetorotational instability (MRI) in accretion discs. The analysis is performed by use of analytical and numerical means. We provide a general…

Solar and Stellar Astrophysics · Physics 2015-05-13 M. Flaig , R. Kissmann , W. Kley

The problem of dynamical heating of galactic discs by spiral density waves is discussed using the shearing sheet model. The secular evolution of the disc is described quantitatively by a diffusion equation for the distribution function of…

Astrophysics · Physics 2009-11-06 B. Fuchs

This paper proposes a physical-statistical modeling approach for spatio-temporal data arising from a class of stochastic convection-diffusion processes. Such processes are widely found in scientific and engineering applications where…

Applications · Statistics 2020-08-07 Xiao Liu , Kyongmin Yeo , Siyuan Lu

Plastic deformation in microscale differs from the macroscopic plasticity in two respects: (i) the flow stress of small samples depends on their size (ii) the scatter of plasticity increases significantly. In this work we focus on the…

Materials Science · Physics 2015-03-10 Olga Kapetanou , Vasilis Koutsos , Efstathios Theotokoglou , Daniel Weygand , Michael Zaiser

Accretion discs are ubiquitous in the universe and it is a crucial issue to understand how angular momentum and mass are being radially transported in these objects. Here, we study the role played by non-linear spiral patterns within…

Astrophysics of Galaxies · Physics 2016-05-04 Patrick Hennebelle , Geoffroy Lesur , Sébastien Fromang

A new method is proposed to numerically extract the diffusivity of a (typically nonlinear) diffusion equation from underlying stochastic particle systems. The proposed strategy requires the system to be in local equilibrium and have…

Statistical Mechanics · Physics 2018-05-09 Peter Embacher , Nicolas Dirr , Johannes Zimmer , Celia Reina

We study the dynamics of super-Eddington accretion flows by performing two-dimensional radiation-hydrodynamic simulations. Compared with previous works, in this paper we include the $T_{\theta\phi}$ component of the viscous stress and…

High Energy Astrophysical Phenomena · Physics 2015-06-16 Xiao-Hong Yang , Feng Yuan , Ken Ohsuga , De-Fu Bu

We have applied an eccentric accretion disc theory in simplified form to the case of an accretion disc in a binary system, where the disc contains the 3:1 Lindblad resonance. This is relevant to the case of superhumps in SU Ursae Majoris…

Astrophysics · Physics 2009-11-11 Simon Goodchild , Gordon Ogilvie

The non-Newtonian behavior of a monodisperse concentrated dispersion of spherical particles was investigated using a direct numerical simulation method, that takes into account hydrodynamic interactions and thermal fluctuations accurately.…

Soft Condensed Matter · Physics 2012-11-22 Takuya Iwashita , Ryoichi Yamamoto

We present the results of four magnetohydrodynamic simulations and one alpha-disk simulation of accretion disks in a compact binary system, neglecting vertical stratification and assuming a locally isothermal equation of state. We…

High Energy Astrophysical Phenomena · Physics 2024-11-26 Morgan Ohana , Yan-Fei Jiang , Omer Blaes , Bryance Oyang

A self-consistent solution for a thin accretion disk with turbulent convection is presented. The disk viscosity and the convective flux are derived from a physical model for turbulence, and expressed in terms of the local physical…

Astrophysics · Physics 2009-10-28 Itzhak Goldman , Amri Wandel

Standard accretion disc model relies upon several assumptions, the most important of which is geometrical thinness. Whenever this condition is violated, new physical effects become important such as radial energy advection and mass loss…

High Energy Astrophysical Phenomena · Physics 2015-10-28 Pavel Abolmasov , Anna Chashkina

A liquid drop spreading over a thin heterogeneous precursor film (such as an inhaled droplet on the mucus-lined wall of a lung airway) will experience perturbations in shape and location as its advancing contact line encounters regions of…

Fluid Dynamics · Physics 2018-07-27 Feng Xu , Sam Coveney , Oliver E. Jensen

Rapid, large amplitude variability at optical to X-ray wavelengths is now seen in an increasing number of Seyfert galaxies and luminous quasars. The variations imply a global change in accretion power, but are too rapid to be communicated…

Astrophysics of Galaxies · Physics 2018-11-28 Jason Dexter , Mitchell C. Begelman

We investigate the time evolution of luminous accretion disks around black holes, conducting the two-dimensional radiation-hydrodynamic simulations. We adopt the alpha prescription for the viscosity. The radial-azimuthal component of…

Astrophysics · Physics 2009-11-11 K. Ohsuga

Photon trapping and outflow are two key physics associated with the supercritical accretion flow. We investigate the conflict between these two processes based on two-dimensional radiation-hydrodynamic (RHD) simulation data and construct a…

High Energy Astrophysical Phenomena · Physics 2015-05-13 Shun Takeuchi , Shin Mineshige , Ken Ohsuga