An Etymological Dictionary of Astronomy and Astrophysics

A → dimensionless quantity used in → magnetohydrodynamics to describe the relative balance of → kinematic viscosity to → magnetic diffusion. It is described by: P_r = σμ₀ν = ν/η, where σ is the → conductivity of the fluid, μ₀ is the → magnetic permeability of the fluid, ν is the kinematic viscosity of the fluid, and η is the → magnetic diffusivity.

See also: → magnetic; → Prandtl number.