Magnetic Reynolds number

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Physical key figure
Surname Magnetic Reynolds number
Formula symbol
dimension dimensionless
definition
magnetic field constant
Electric conductivity
characteristic speed
characteristic length
magnetic diffusivity
Named after Osborne Reynolds
scope of application magnetic fluids
See also: Reynolds number

In magnetohydrodynamics , a magnetic Reynolds number is defined analogous to the Reynolds number in hydrodynamics . It is a dimensionless number and describes the ratio of convection to diffusion in a magnetic fluid .

It is defined as:

.

Where:

Scale and examples

If a copper loop of the diameter is moved with the speed (conductivity ), this results

  • For the magnetic field is diffuse or is hardly influenced by the movement.

The magnetic Reynolds number is of the order of magnitude:

  • a liquid metal , e.g. B. Mercury : ,
  • in industrial applications: ,
  • in the outer core of the earth : and
  • in astrophysics : .

Web links

Individual evidence

  1. OV Filipenko, BG Zinchenko, DD Sokoloff: Turbulent Dynamo and the Geomagnetic Secular Variation . In: Solar and Planetary Dynamos . tape 1 . Cambridge University Press, 2008, ISBN 0-521-05415-X , pp. 229 ( limited preview in Google Book search).