# Nusselt Number

Written by Jerry Ratzlaff on . Posted in Dimensionless Numbers

## Nusselt Number

Nusselt number ( $$Nu$$ ) (dimensionless number) is a ratio of convective heat transfer to conductive heat across a boundary.

### Nusselt Number FORMULA

$$\large{ Nu=\frac{h l}{k} }$$

Where:

$$\large{ Nu }$$ = Nusselt number

$$\large{ h }$$ = heat transfer coefficient

$$\large{ l }$$ = characteristic length

$$\large{ k }$$ = thermal conductivity

Solve for:

$$\large{ h=\frac{ Nu k }{ l } }$$

$$\large{ l=\frac{ Nu k }{ h } }$$

$$\large{ k=\frac{ h l }{ Nu } }$$