Elliptical flow instability in a conducting fluid triggered by an external magnetic field

Area of Science:

• Plasma physics
• Astrophysical fluid dynamics

Background:

• Anticyclonic flows in astrophysical contexts often feature vortices.
• Understanding turbulence and transport in these vortices is crucial for accretion disk models.

Purpose of the Study:

• To investigate the effect of weak magnetic fields on anticyclonic, recirculating flows.
• To identify novel mechanisms for turbulence generation and angular momentum transport in vortex cores.

Main Methods:

• Theoretical analysis of magnetohydrodynamic instabilities.
• Numerical simulations of plasma flow under magnetic influence.

Main Results:

• Demonstration that arbitrarily weak magnetic fields can induce violent instability in flows with uniform mean angular velocity.
• Identification of this magnetohydrodynamic instability as a trigger for turbulence in vortex cores, where other instabilities are ineffective.
• Highlighting the role of this instability in enhancing outward angular momentum transport in accretion disk vortices.

Conclusions:

• A weak magnetic field is sufficient to destabilize anticyclonic flows.
• This instability provides a mechanism for turbulence and enhanced transport in regions previously thought stable.
• The findings have implications for understanding accretion disk evolution and vortex dynamics.