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Related papers: Self-Similar Accretion Flows with Convection

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A self-similar solution for time evolution of quasi-spherical, self-gravitating accretion flows is obtained under the assumption that the generated heat by viscosity is retained in the flow. The solutions are parameterized by the ratio of…

Astrophysics · Physics 2009-11-10 Mohsen Shadmehri

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

In a previous paper we have written down equations describing steady-state, optically thin, advection-dominated accretion onto a Kerr black hole (Gammie and Popham 1997, hereafter Paper I). In this paper we survey the numerical solutions to…

Astrophysics · Physics 2009-10-30 Robert Popham , Charles F. Gammie

We use the standard Runge-Kutta method to solve the set of basic equations describing black hole accretion flows composed of two-temperature plasma. We do not invoke any extra energy transport mechanism such as thermal conduction and do not…

Astrophysics · Physics 2009-11-10 Ju-Fu Lu , Yi-Qing Lin , Wei-Min Gu

The growing evidence for supermassive black holes in the centres of nearby galaxies has brought into sharper focus the question of why elliptical galaxies, rich in hot gas, do not possess quasar-like luminosities. Recent studies suggest…

Astrophysics · Physics 2015-06-24 T. Di Matteo , A. C. Fabian , M. J. Rees , C. L. Carilli , R. J. Ivison

We investigate the dynamics of clumps that coexisted with/in advection-dominated accretion flows by considering thermal conductivity. Thermal conduction can be one of the effective factors in the energy transportation of ADAFs; hence it may…

High Energy Astrophysical Phenomena · Physics 2022-11-09 Hussein Ayad , Maryam Samadi , Shahram Abbassi

We examine flow and transport through an orifice in a flat wall separating semi-infinite atmospheres of two dissimilar gases. The analysis assumes steady conditions and order-unity values of the Schmidt number Sc and P\'eclet number Pe,…

Fluid Dynamics · Physics 2026-02-25 Mario Sánchez Sanz , Antonio L. Sánchez

Using mean field MHD, we discuss the energetics of optically thin, two temperature, advection-dominated accretion flows (ADAFs). If the magnetic field is tangled and roughly isotropic, flux freezing is insufficient to maintain the field in…

Astrophysics · Physics 2009-10-31 Eliot Quataert , Ramesh Narayan

It has been suggested that the laws of thermodynamics are violated by what we have called a convection-dominated accretion flow (or a 1/2-law accretion flow) -- an accretion flow characterized by a constant outflow of energy. We show that…

Astrophysics · Physics 2007-05-23 Andrei Gruzinov

We examine the effects of a hydrodynamical wind on advection dominated accretion flows with thermal conduction in the presence of a toroidal magnetic field under a self-similar treatment. The disk gas is assumed to be isothermal. For a…

Astrophysics of Galaxies · Physics 2010-12-16 S. Abbassi , J. Ghanbari , M. Ghasemnezhad

We solve the radiation-hydrodynamic (RHD) equations of supercritical accretion flows in the presence of radiation force and outflow by using self similar solutions. Compare with the pioneer works, in this paper we consider power-law…

High Energy Astrophysical Phenomena · Physics 2016-06-01 Fatemeh Zahra Zeraatgari , Shahram Abbassi , Amin Mosallanezhad

(Abridged) We study the effects of a global magnetic field on viscously-rotating and vertically-integrated accretion disks around compact objects using a self-similar treatment. We extend Akizuki & Fukue's work (2006) by discussing a…

Astrophysics · Physics 2015-05-13 Dong Zhang , Z. G. Dai

Differentially rotating, "advection-dominated" accretion flows are considered in which the heat generated by viscous dissipation is retained in the fluid. The equations of time-dependent quasi-spherical accretion are solved in a simplified…

Astrophysics · Physics 2009-10-31 G. I. Ogilvie

We present self-similar solutions for advection -dominated accretion flows with thermal conduction in the presence of outflows. Possible effects of outflows on the accretion flow are parametrized and a saturated form of thermal conduction,…

Astrophysics · Physics 2009-11-13 Mohsen Shadmehri

We suggest a model of the advection dominated accretion flow (ADAF) with magnetically driven outflows to explain hysteretic state transition observed in X-ray binaries (XRBs). The transition from a thin disk to an ADAF occurs when the mass…

High Energy Astrophysical Phenomena · Physics 2016-01-27 Xinwu Cao

Radiatively inefficient accretion flows onto black holes are unstable due to both an outwardly decreasing entropy (`convection') and an outwardly decreasing rotation rate (the `magnetorotational instability'; MRI). Using a linear…

Astrophysics · Physics 2009-11-07 Ramesh Narayan , Eliot Quataert , Igor V. Igumenshchev , Marek A. Abramowicz

Based on no-outflow assumption, we investigate steady state, axisymmetric, optically thin accretion flows in spherical coordinates. By comparing the vertically integrated advective cooling rate with the viscous heating rate, we find that…

High Energy Astrophysical Phenomena · Physics 2015-06-23 Wei-Min Gu

Recent papers discussing advection dominated accretion flows (ADAF) as a solution for astrophysical accretion problems should be treated with some caution because of their uncertain physical basis. The suggestions underlying ADAF involve…

Astrophysics · Physics 2009-10-31 G. S. Bisnovatyi-Kogan , R. V. E. Lovelace

A new one-dimensional, dynamical model is proposed for geometrically thin, self-gravitating viscous accretion discs. The vertically integrated equations are simplified using the slow accretion limit and the monopole approximation with a…

Astrophysics of Galaxies · Physics 2015-04-30 Tobias F. Illenseer , Wolfgang J. Duschl

Convection has been discussed in the field of accretion discs for several decades, both as a means of angular momentum transport and also because of its role in controlling discs' vertical structure via heat transport. If the gas is…

Solar and Stellar Astrophysics · Physics 2021-04-21 Loren E. Held , Henrik N. Latter