# Prandtl number - depending on the fluid properties

## Description

The Prandtl number (Pr) or Prandtl group is a dimensionless number, named after the German physicist Ludwig Prandtl, defined as the ratio of momentum diffusivity to thermal diffusivity. It can alternatively be expressed as shown here.

Related formulas## Variables

Pr | Prandtl number (dimensionless) |

c_{p} | specific heat, (SI units: J/kgK) (J/kg*K) |

μ | dynamic viscosity, (SI units: Pa s = N s/m^2) (Pa*s) |

λ | thermal conductivity, (SI units: W/mK) (W/m*K) |