# Prandtl Number

Written by Jerry Ratzlaff. Posted in Dimensionless Numbers

Prandtl Number is a dimensionless number used to calculate force by the ratio of momentum diffusivity (kinematic viscosity) and thermal diffusivities.

## FORMULA

$$Pr= \frac{\nu} {\alpha}$$

Where:

$$Pr$$ = Prandtl Number

$$\nu$$ = kinematic viscosity

$$\alpha$$ = thermal diffusivity

Solve for:

$$\nu = Pr \alpha$$

$$\alpha = \frac { \nu }{ Pr }$$