Wetted Perimeter

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

 

Wetted perimeter formulas

\(\large{ P_w = \frac{ A_c }{ r_h }   }\)
\(\large{ P_w = 2 \; h \; \sqrt  {1  +  z^2 }  }\)	(hydraulic radius)
\(\large{ P_w =  r \;  \theta }\)	(Hydraulic Radius of a Partially Full Pipe (Less than Half Full))
\(\large{ P_w =  2 \; \pi \; r  - r \;  \theta }\)	(Hydraulic Radius of a Partially Full Pipe (More than Half Full))

Where:

\(\large{ P_w }\) = wetting perimeter

\(\large{ A_c }\) = area cross-section of flow

\(\large{ \theta }\)   (Greek symbol theta) = degree

\(\large{ h }\) = depth of fluid

\(\large{ r_h }\) = hydraulic radius

\(\large{ \pi }\) = Pi

\(\large{ r }\) = radius

\(\large{ z }\) = width of channel slope