# Hydraulic Radius of a Partially Full Pipe (Less than Half Full)

Written by Jerry Ratzlaff on . Posted in Fluid Dynamics

$$\large{ r_h = \frac { A_c } { P_w } }$$
$$\large{ r_h }$$ = hydraulic radius $$\large{ in }$$ $$\large{ mm }$$
$$\large{ A_c }$$ = area cross-section of flow $$\large{ in^2 }$$ $$\large{ mm^2 }$$
$$\large{ P_w }$$ = wetting perimeter $$\large{ in }$$ $$\large{ mm }$$