Nath, SK and Mukhopadhyay, B (2018) Emergence of nonlinearity and plausible turbulence in accretion disks via hydromagnetic transient growth faster than magnetorotational instability. In: 14th Marcel Grossman Meeting On Recent Developments in Theoretical and Experimental General Relativity, Astrophysics and Relativistic Field Theories, 12 - 18 July 2015, Rome, pp. 1120-1125.
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Abstract
We investigate the evolution of hydromagnetic perturbations in a small section of accretion disks. It is known that molecular viscosity is negligible in accretion disks. Hence, it has been argued that Magnetorotational Instability (MRI) is responsible for transporting matter in the presence of weak magnetic field. However, there are some shortcomings, which question effectiveness of MRI. Now the question arises, whether other hydromagnetic effects, e.g. transient growth (TG), can play an important role to bring nonlinearity in the system, even at weak magnetic fields. Otherwise, whether MRI or TG, which is primarily responsible to reveal nonlinearity to make the flow turbulent? Our results prove explicitly that the flows with high Reynolds number (Re), which is the case of realistic astrophysical accretion disks, exhibit nonlinearity by best TG of perturbation modes faster than that by best modes producing MRI. For a fixed wavevector, MRI dominates over transient effects, only at low Re, lower than its value expected to be in astrophysical accretion disks, and low magnetic fields. This seriously questions (overall) persuasiveness of MRI in astrophysical accretion disks. Copyright © 2018 by the Editors.All rights reserved.
| Item Type: | Conference Paper |
|---|---|
| Publication: | 14th Marcel Grossman Meeting On Recent Developments in Theoretical and Experimental General Relativity, Astrophysics and Relativistic Field Theories, Proceedings |
| Publisher: | World Scientific Publishing Co. Pte. Ltd. |
| Additional Information: | The copyright for this article belongs to the Authors. |
| Keywords: | Magnetohydrodynamics; Plasma stability; Relativity; Reynolds number; Stability; Turbulence, Accretion disks; High Reynolds number; Low magnetic fields; Magnetorotational instability; Molecular viscosity; Transient effect; Transient growth; Weak magnetic fields, Astrophysics |
| Department/Centre: | Division of Physical & Mathematical Sciences > Physics |
| Date Deposited: | 01 Sep 2022 10:22 |
| Last Modified: | 01 Sep 2022 10:22 |
| URI: | https://eprints.iisc.ac.in/id/eprint/76349 |
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