Flow curvature effects on the parallel velocity shear driven instability: MHD simulations

ABSTRACT

This paper presents results of magnetohydrodynamic (MHD) simulations of flow curvature effects on the parallel velocity shear (PVS) driven instability in a magnetized plasma. Three flow profiles with identical velocity shear but different velocity curvature: positive curvature, no curvature, and negative curvature, are investigated with an MHD model. The total velocity jump of the positive curvature flow is $29\mathrm{\%}$ higher than the linear flow, and the total velocity jump of the negative curvature flow is $29\mathrm{\%}$ lower than the linear flow. It is found that by the same simulation time, the flow profile with a positive curvature yields more developed plasma density and magnetic field vortices compared with the other two flow profiles with linear and negative curvature flow profiles. The curvature effects are further quantitatively characterized by examining the transverse perturbations. The transverse kinetic energy growth rate of the positive curvature flow is $19\mathrm{\%}$ higher than the linear flow, and $68\mathrm{\%}$ higher than the negative curvature flow. The difference in growth rate appears to be comparable with the difference in the velocity shear frequency and consistent with previous theoretical work.

KEYWORDS:

• PVS instability
• flow curvature
• MHD model

Acknowledgments

Professor Binzheng Zhang from the University of Hong Kong provided the MHD simulation code. The authors acknowledge Advanced Research Computing (ARC) at Virginia Tech and the Space Computer Center (SpaceCC) of the Electrical and Computer Engineering Department for providing computational resources and technical support that have contributed to the results reported within this paper.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

D. Lin  http://orcid.org/0000-0003-2894-6677

W. Scales  http://orcid.org/0000-0002-6986-6086

Additional information

Funding

This study was supported under U.S. Department of Energy - DOE grant DE-SC0016397. Support was also provided by the Airforce Office of Scientific Research.