# Hydraulic Radius of a Pipe

Written by Jerry Ratzlaff on . Posted in Fluid Dynamics

Hydraulic radius, abbreviated as $$r_h$$, is the cross-section area of water in a pipe or channel divided by the wetting perimeter.

### Hydraulic Radius of a Pipe formula

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

Where:

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

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

$$\large{ P }$$ = wetted perimeter

Solve for:

$$\large{ A = r_h \; P }$$

$$\large{ P = A \; r_h }$$