Inverse cascade suppression and shear-layer formation in magnetohydrodynamic turbulence subject to a guide field and misaligned rotation
Name
2104.12746.pdf
Description
Accepted version
Size
696.51 KB
Format
Adobe PDF
Checksum (MD5)
97849cdddedc0df9a1f9f16b6ef5ea12
Author(s)
Benavides, Santiago J
Burns, Keaton J
Gallet, Basile
Cho, James Y-K
Flierl, Glenn R
Date Issued
2022
Journal
Journal of Fluid Mechanics
Publisher
Cambridge University Press (CUP)
Citation
Benavides, Santiago J, Burns, Keaton J, Gallet, Basile, Cho, James Y-K and Flierl, Glenn R. 2022. "Inverse cascade suppression and shear-layer formation in magnetohydrodynamic turbulence subject to a guide field and misaligned rotation." Journal of Fluid Mechanics, 935.
Version
Author's final manuscript
Abstract
Astrophysical flows are often subject to both rotation and large-scale background magnetic fields. Individually, each is known to two-dimensionalize the flow in the perpendicular plane. In realistic settings, both of these effects are simultaneously present and, importantly, need not be aligned. In this work, we numerically investigate three-dimensional forced magnetohydrodynamic turbulence subject to the competing effects of global rotation and a perpendicular background magnetic field. We focus on the case of a strong background field and find that increasing the rotation rate from zero produces significant changes in the structure of the turbulent flow. Starting with a two-dimensional inverse energy cascade at zero rotation, the flow first transitions to a forward cascade of kinetic energy, then to a shear-layer dominated regime and finally to a second shear-layer regime where the kinetic energy flux is strongly suppressed and the energy transfer is mediated by the induced magnetic field. We show that the first two transitions occur at distinct values of the Rossby number, and the third occurs at a distinct value of the Lehnert number. The three-dimensional results are confirmed using an asymptotic two-dimensional, three-component model, which allows us to extend our results to the planetary-relevant case of an arbitrary angle between the rotation vector and guide field. More generally, our results demonstrate that, when considering the simultaneous limits of strong rotation and a strong guide field, the order in which those limits are taken matters in the misaligned case.
MIT Department
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
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DOI of Published Version
https://doi.org/10.1017/JFM.2021.968
