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Magnetohydrodynamics of Accretion Di...

Ju, Wenhua.

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Magnetohydrodynamics of Accretion Disks in Cataclysmic Variables.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Magnetohydrodynamics of Accretion Disks in Cataclysmic Variables./
Author:	Ju, Wenhua.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 2016,
Description:	245 p.
Notes:	Source: Dissertation Abstracts International, Volume: 78-04(E), Section: B.
Contained By:	Dissertation Abstracts International78-04B(E).
Subject:	Astrophysics. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=10167605
ISBN:	9781369219531

Magnetohydrodynamics of Accretion Disks in Cataclysmic Variables.
Ju, Wenhua.

Magnetohydrodynamics of Accretion Disks in Cataclysmic Variables. - Ann Arbor : ProQuest Dissertations & Theses, 2016 - 245 p.

Source: Dissertation Abstracts International, Volume: 78-04(E), Section: B.

Thesis (Ph.D.)--Princeton University, 2016.

Angular momentum transport in the accretion disks of cataclysmic variables (CVs) is a crucial ingredient of driving the evolution of CVs and is believed to account for the observed episodic outbursts in dwarf novae. However, the physical mechanisms of driving angular momentum transport in CV disks are not well understood yet. In this thesis, the angular momentum transport driven by the spiral shocks and the magnetorotational instability (MRI) is thoroughly studied using a series of global hydrodynamical and magnetohydrodynamical (MHD) simulations conducted with Athena++.

ISBN: 9781369219531Subjects--Topical Terms:

535904
Astrophysics.

Magnetohydrodynamics of Accretion Disks in Cataclysmic Variables.
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100 1 $a Ju, Wenhua. $3 3284476
245 1 0 $a Magnetohydrodynamics of Accretion Disks in Cataclysmic Variables.
260 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 2016
300 $a 245 p.
500 $a Source: Dissertation Abstracts International, Volume: 78-04(E), Section: B.
500 $a Adviser: James M. Stone.
502 $a Thesis (Ph.D.)--Princeton University, 2016.
520 $a Angular momentum transport in the accretion disks of cataclysmic variables (CVs) is a crucial ingredient of driving the evolution of CVs and is believed to account for the observed episodic outbursts in dwarf novae. However, the physical mechanisms of driving angular momentum transport in CV disks are not well understood yet. In this thesis, the angular momentum transport driven by the spiral shocks and the magnetorotational instability (MRI) is thoroughly studied using a series of global hydrodynamical and magnetohydrodynamical (MHD) simulations conducted with Athena++.
520 $a Spiral shocks are a possible accretion mechanism in cold quiescence state when the CV disk may be too cool and neutral for the MRI to operate. We perform global two-dimensional hydrodynamical simulations where we found mass accretion is driven by deposition of negative angular momentum carried by the waves through shock dissipation. The effective viscosity parameter alpha eff is 0.02--0.05 when the disk Mach number is < 10. Spiral shocks are found very sensitive to the size and Mach number of the disk: they are stronger with larger disk sizes or lower Mach numbers. We also apply the spiral shock analysis to circumplanetary disks (CPDs) and found spiral shocks can contribute significantly to the angular momentum transport and energy dissipation in CPDs yielding alphaeff &sim; 0.001--0.02.
520 $a In hot outburst state the CV disk is ionized so MRI and spiral shocks both drive angular momentum transport. We perform global three-dimensional MHD simulations of CV disks to investigate the relative importance of spiral shocks and MRI. Our steady-state solutions indicate that the relative importance in driving angular momentum transport of spiral shocks and MRI is mostly determined by the gas Mach number and the seed magnetic field strength, and is independent of the seed field geometry. While the mass accretion rate in steady-state disks is always equal to the mass supply rate, the steady-state alpha eff is larger when the seed magnetic field has vertical components or the flow has stronger magnetization.
590 $a School code: 0181.
650 4 $a Astrophysics. $3 535904
690 $a 0596
710 2 $a Princeton University. $b Astrophysical Sciences. $3 3193121
773 0 $t Dissertation Abstracts International $g 78-04B(E).
790 $a 0181
791 $a Ph.D.
792 $a 2016
793 $a English
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=10167605