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Related Experiment Video

Updated: Jun 18, 2026

The Diffusion of Passive Tracers in Laminar Shear Flow

The Diffusion of Passive Tracers in Laminar Shear Flow

Published on: May 1, 2018

Eddy diffusivity from hydromagnetic Taylor-Couette flow experiments.

Marcus Gellert¹, Günther Rüdiger

¹Astrophysikalisches Institut Potsdam, Potsdam, Germany. mgellert@aip.de

Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics

|November 13, 2009

Summary

Hydromagnetic Taylor-Couette flow stability is analyzed. Numerical simulations reveal induced electromotive forces can measure eddy diffusivity, potentially applicable in laboratory settings like sodium experiments.

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Generation and Control of Electrohydrodynamic Flows in Aqueous Electrolyte Solutions

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Published on: September 7, 2018

Area of Science:

Fluid dynamics
Magnetohydrodynamics
Plasma physics

Background:

The stability of hydromagnetic Taylor-Couette flows with toroidal magnetic fields is crucial for understanding astrophysical and industrial processes.
Previous studies primarily focused on current-free magnetic fields, leaving the stability under uniform fields less explored.

Purpose of the Study:

To investigate the stability of hydromagnetic Taylor-Couette flows with toroidal magnetic fields across various magnetic Prandtl numbers.
To analyze the role of induced electromotive forces in stabilizing magnetic kink-type instabilities.
To explore the potential of using these effects for laboratory measurements of eddy diffusivity.

Main Methods:

Numerical simulations were employed to study the flow stability.
Analysis focused on the dependence of induced electromotive forces on magnetic diffusivity and viscosity.
Theoretical considerations for laboratory experiments were outlined.

Main Results:

Toroidal magnetic fields become unstable at high Hartmann numbers due to magnetic kink-type instability, which is mitigated by basic rotation.
The induced electromotive force, driven by axial electric current, reduces instability and depends on molecular magnetic diffusivity, not viscosity.
Simulations suggest eddy diffusivity is comparable to molecular diffusivity for all magnetic Prandtl numbers.

Conclusions:

The induced electromotive force offers a novel method for measuring eddy diffusivity in laboratory settings.
A sodium experiment could yield a detectable potential difference, validating the theoretical predictions.
This research provides insights into the stability of magnetized fluid flows and potential experimental applications.