Magnetic Prandtl number

The Magnetic Prandtl number (Pr_m) is a dimensionless quantity occurring in magnetohydrodynamics which approximates the ratio of momentum diffusivity (viscosity) and magnetic diffusivity. It is defined as:

where:

• is the magnetic Reynolds number
• is the Reynolds number
• is the momentum diffusivity (kinematic viscosity)
• is the magnetic diffusivity

At the base of the Sun's convection zone the Magnetic Prandtl number is approximately 10^{−2}, and in the interiors of planets and in liquid-metal laboratory dynamos is approximately 10^{−5}.

See also

• Prandtl number

References