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Magnetic induction and diffusion mechanisms in a liquid sodium spherical Couette experiment
Simon Cabanes1, Nathanaël Schaeffer1, Henri-Claude Nataf1
1ISTerre, Université Grenoble Alpes, F-38000 Grenoble, France; CNRS, ISTerre, F-38000 Grenoble, France; and IRD, ISTerre, F-38000 Grenoble, France.
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|November 7, 2014
Summary
Researchers reconstructed fluid flows in a liquid sodium experiment using a rotating magnetic field. They observed superrotation driven by magnetic forces near the inner sphere and hindered meridional circulation.
Area of Science:
- Magnetohydrodynamics
- Fluid dynamics
Background:
- Spherical Couette flow experiments are crucial for understanding astrophysical and geophysical phenomena.
- Liquid sodium experiments provide insights into fluid behavior under extreme conditions.
Purpose of the Study:
- To reconstruct the mean axisymmetric azimuthal and meridional flows in the Derviche Tourneur Sodium experiment.
- To analyze the influence of a rotating magnetic field on fluid dynamics.
Main Methods:
- Utilized measurements of mean velocity, induced magnetic field, and electric potentials.
- Developed a nonlinear least-squares inversion procedure based on the induction equation.
- Included the fluid layer's response to non-axisymmetric magnetic fields.
Main Results:
- Observed superrotation in the inner region dominated by the Lorentz force.
- Identified an outer geostrophic region governed by the Coriolis force, with magnetic torque as the driver.
- Found that meridional circulation is hindered by Lorentz and Coriolis forces but contributes significantly to induced magnetic energy.
Conclusions:
- The study successfully reconstructed complex flow fields in a liquid sodium experiment.
- The findings highlight the interplay between magnetic forces, Coriolis forces, and fluid flow.
- This work provides a foundation for investigating the role of fluctuations in dynamo mechanisms.
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