The Prandtl number is a dimensionless quantity used in fluid mechanics and heat transfer to describe the ratio of momentum diffusivity to thermal diffusivity in a fluid.
- Pr is the Prandtl number,
- μ∞ is the dynamic viscosity of the fluid at a reference temperature,
- cp is the specific heat at constant pressure of the fluid at the same reference temperature,
- k∞ is the thermal conductivity of the fluid at the reference temperature.