Dynamo Action in a Quasi-Keplerian Taylor-Couette Flow.

Area of Science:

• Fluid dynamics
• Magnetohydrodynamics
• Plasma physics

Background:

• Taylor-Couette flow with quasi-Keplerian rotation is typically Rayleigh stable.
• Nonmagnetic systems in this regime lack kinematic dynamo action.

Purpose of the Study:

• To numerically investigate dynamo action in a quasi-Keplerian Taylor-Couette flow.
• To determine if turbulence and magnetic fields can mutually sustain each other.

Main Methods:

• Numerical computation of electrically conducting fluid flow.
• Utilizing a quasi-Keplerian rotation rate: Ω_{o}/Ω_{i}=(r_{o}/r_{i})^{-3/2}.
• Simulations performed at Reynolds number (Re) = 10^4 and magnetic Reynolds number (Rm) = 10^5.

Main Results:

• Demonstrated the existence of a finite-amplitude dynamo.
• Observed mutually sustaining turbulence and magnetic fields.
• Significant increase in outward angular momentum transport.

Conclusions:

• A dynamo can exist in this stable, nonmagnetic configuration.
• Maxwell stresses dominate angular momentum transport over Reynolds stresses.
• Finite-amplitude dynamos can arise from specific initial conditions.