rayleigh number definition
Rayleigh number, Ra, is a dimensionless term used in the calculation of natural convection. where g is acceleration due to gravity, Î²' is coefficient of thermal expansion of the fluid, Î´T is temperature difference, x is length, Î½ is kinematic viscosity and Îº is thermal diffusivity of the fluid. Gr is the Grashof Number and Pr is the Prandtl Number.