Bulletin of the American Physical Society
64th Annual Meeting of the APS Division of Plasma Physics
Volume 67, Number 15
Monday–Friday, October 17–21, 2022; Spokane, Washington
Session JI01: Astrophysical/Space Plasmas I
2:00 PM–5:00 PM,
Tuesday, October 18, 2022
Room: Ballroom 100 A
Chair: Maxim Lyutikov, Purdue Univ.
Abstract: JI01.00004 : A New Mechanism for Sequestering Magnetic Energy at Large Scales in Shear-Flow Turbulence*
3:30 PM–4:00 PM
Presenter:
Bindesh Tripathi
(University of Wisconsin - Madison)
Authors:
Bindesh Tripathi
(University of Wisconsin - Madison)
Adrian E Fraser
(University of California, Santa Cruz)
Paul W Terry
(UW Madison)
Ellen G Zweibel
(University of Wisconsin - Madison)
M.J. Pueschel
(Dutch Institute for Fundamental Energy Research)
Kelvin-Helmholtz instability excites, through nonlinear effects, large-scale linearly stable eigenmodes, including an important conjugate-root of the instability. It is shown, by removing these latter stable (damped) modes in high resolution numerical simulations of two-dimensional (2D) MHD turbulence, that the flow composed of the unstable modes alone distorts and folds the magnetic field lines unimpeded, rapidly producing a small-scale energy cascade. Retaining the stable modes, in contrast, significantly weakens the small-scale dissipation, and the rapid generation of small scales is not observed.1 Computations of energy transfer between the eigenmodes reveal appreciable cancellation of up- and down-scale kinetic and magnetic cascades. In the shear layer, up-gradient momentum transport by the stable modes is found to cancel 70%-90% of down-gradient momentum transport by the unstable modes. These findings persist even with a strong flow-aligned magnetic field that nearly quenches the instability, and with variations in the magnetic Prandtl number from 0.1 to 10.2 Near-identical impact of stable modes is found in 3D turbulence, as well. It is suggested that the nonlinearly excited stable modes may also play an important role in reconnection-driven outflows, which can be consequential to the emerging theories of the MHD turbulence.
[1] Tripathi et al., Phys. Plasmas 29, 070701 (2022). DOI:10.1063/5.0096886
[2] Tripathi et al., submitted to PoP.
*Funded by the Department of Energy [DE-SC0022257] through the NSF/DOE Partnership in Basic Plasma Science and Engineering.
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700