Mak, J, Griffiths, SD and Hughes, DW orcid.org/0000-0002-8004-8631 (2017) Vortex disruption by magnetohydrodynamic feedback. Physical Review Fluids, 2 (11). 113701. ISSN 2469-990X
Abstract
In an electrically conducting fluid, vortices stretch out a weak, large-scale magnetic field to form strong current sheets on their edges. Associated with these current sheets are magnetic stresses, which are subsequently released through reconnection, leading to vortex disruption, and possibly even destruction. This disruption phenomenon is investigated here in the context of two-dimensional, homogeneous, incompressible magnetohydrodynamics. We derive a simple order of magnitude estimate for the magnetic stresses—and thus the degree of disruption—that depends on the strength of the background magnetic field (measured by the parameter M, a ratio between the Alfvén speed and a typical flow speed) and on the magnetic diffusivity (measured by the magnetic Reynolds number Rm). The resulting estimate suggests that significant disruption occurs when M²Rm=O(1). To test our prediction, we analyze direct numerical simulations of vortices generated by the breakup of unstable shear flows with an initially weak background magnetic field. Using the Okubo-Weiss vortex coherence criterion, we introduce a vortex disruption measure, and show that it is consistent with our predicted scaling, for vortices generated by instabilities of both a shear layer and a jet.
Metadata
Item Type: | Article |
---|---|
Authors/Creators: |
|
Copyright, Publisher and Additional Information: | (c) 2017, American Physical Society. This is an author produced version of a paper published in Physical Review Fluids. Uploaded in accordance with the publisher's self-archiving policy. |
Dates: |
|
Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Mathematics (Leeds) > Applied Mathematics (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 07 Nov 2017 14:01 |
Last Modified: | 21 Dec 2017 22:46 |
Status: | Published |
Publisher: | American Physical Society |
Identification Number: | 10.1103/PhysRevFluids.2.113701 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:123478 |