# Wetted Perimeter

Written by Jerry Ratzlaff on . Posted in Fluid Dynamics

Wetting perimeter is the portion of the channel that is in contact with the fluid flowing.

### Wetted perimeter Formula

$$\large{ P_w = \frac{ A }{ r_h } }$$

Where:

$$\large{ P_w }$$ = wetting perimeter

$$\large{ A }$$ = cross-section flow area

$$\large{ r_h }$$ = hydraulic radius