Magnetic Reynolds number

Analogous to the Reynolds number in hydrodynamics is defined in the MHD magnetic Reynolds number. It is a dimensionless parameter and denotes the ratio of convection to diffusion in a magnetic fluid.

It is defined as:

Where:

• The magnetic field constant,
• The electric conductivity ( conductivity ) of the fluid,
• The characteristic length of the use case and
• The amount of the characteristic for the application speed.

Magnitude and examples

If a copper loop of the diameter at the speed moves (conductivity ) concerns

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

The magnetic Reynolds number is in the order:

• A liquid metal such as mercury:
• In industrial applications:
• The Earth's core: and
• In astrophysics.