Magnetic Prandtl number


Magnetic Prandtl number

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

\mathit{Pr_m} = \frac{\mathit{Re_m}}{\mathit{Re}} = \frac{\nu}{\eta} = \frac{\mbox{viscous diffusion rate}}{\mbox{magnetic diffusion rate}}

where:

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

References


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Magnetic Reynolds number — The Magnetic Reynolds number is a dimensionless group that occurs in magnetohydrodynamics. It gives an estimate of the effects of magnetic advection to magnetic diffusion, and is typically defined by: where U is a typical velocity scale of the… …   Wikipedia

  • Prandtl number — The Prandtl number mathrm{Pr} is a dimensionless number approximating the ratio of momentum diffusivity (kinematic viscosity) and thermal diffusivity. It is named after the German physicist Ludwig Prandtl.It is defined as::mathrm{Pr} = frac{… …   Wikipedia

  • Chandrasekhar number — The Chandrasekhar number is a dimensionless quantity used in magnetic convection to represent ratio of the Lorentz force to the viscosity. It is named after the Indian astrophysicist Subrahmanyan Chandrasekhar. The number s main function is as a… …   Wikipedia

  • Nusselt number — In heat transfer at a boundary (surface) within a fluid, the Nusselt number is the ratio of convective to conductive heat transfer across (normal to) the boundary. Named after Wilhelm Nusselt, it is a dimensionless number. The conductive… …   Wikipedia

  • Rayleigh number — In fluid mechanics, the Rayleigh number for a fluid is a dimensionless number associated with buoyancy driven flow (also known as free convection or natural convection). When the Rayleigh number is below the critical value for that fluid, heat… …   Wikipedia

  • Stanton number — The Stanton number, St or CH, is a dimensionless number that measures the ratio of heat transferred into a fluid to the thermal capacity of fluid. It is used to characterize heat transfer in forced convection flows. where h = convection heat… …   Wikipedia

  • Morton number — For Morton number in number theory, see Morton number (number theory). In fluid dynamics, the Morton number (Mo) is a dimensionless number used together with the Eötvös number to characterize the shape of bubbles or drops moving in a surrounding… …   Wikipedia

  • Ohnesorge number — The Ohnesorge number, Oh, is a dimensionless number that relates the viscous forces to inertial and surface tension forces. It is defined as: Where μ is the liquid viscosity ρ is the liquid density σ is the surface tension L is the characteristic …   Wikipedia

  • Keulegan–Carpenter number — The Keulegan–Carpenter number is important for the computation of the wave forces on offshore platforms. In fluid dynamics, the Keulegan–Carpenter number, also called the period number, is a dimensionless quantity describing the relative… …   Wikipedia

  • Dean number — The Dean number is a dimensionless group in fluid mechanics, which occurs in the study of flow in curved pipes and channels. It is named after the British scientist W. R. Dean, who studied such flows in the 1920s (Dean, 1927, 1928). Definition… …   Wikipedia