Wetted Perimeter

Written by Jerry Ratzlaff on . Posted in Fluid Dynamics

hydraulic wetted channel 1hydraulic wetted pipe 1Wetting perimeter, abbreviated as P_w, is the portion of the channel or pipe that is in contact with the fluid flowing.

 

 

 

 

 

 

 

 

 

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Wetting perimeter of a circular pipe formula

\(\large{ P_w =  cos^{-1} \left( 1 - \frac{h}{r} \right) \; d }\)
Symbol English Metric
\(\large{ P_w }\) = wetting perimeter \(\large{ in }\) \(\large{ mm }\)
\(\large{ d }\) = outside diameter \(\large{ in }\) \(\large{ mm }\)
\(\large{ h }\) = fluid depth \(\large{ in }\) \(\large{ mm }\)
\(\large{ r }\) = radius \(\large{ in }\) \(\large{ mm }\)

 

hydraulic radius of a pipe more than half 2

 

 

 

 

 

 

 

 

 

 

Wetting perimeter of a Rectangular Channel formula

\(\large{ P_w =  b + 2 \; h  }\)
Symbol English Metric
\(\large{ P_w }\) = wetting perimeter \(\large{ ft }\) \(\large{ m }\)
\(\large{ b }\) = bottom width \(\large{ ft }\) \(\large{ m }\)
\(\large{ h }\) = fluid depth \(\large{ ft }\) \(\large{ m }\)

 

hydraulic radius of a trapezoid ES 5

Wetting perimeter of a Trapezoidal Channel formula

\(\large{ P_w =  b + 2 \; \left(  \left(  \frac{t \;-\;b}{2}  \right)^2  + h^2  \right)^\frac{1}{2}   }\)
Symbol English Metric
\(\large{ P_w }\) = wetting perimeter \(\large{ ft }\) \(\large{ m }\)
\(\large{ b }\) = bottom width of liquid \(\large{ ft }\) \(\large{ m }\)
\(\large{ t }\) = top width of liquid \(\large{ ft }\) \(\large{ m }\)
\(\large{ h }\) = fluid depth \(\large{ ft }\) \(\large{ m }\)

 

hydraulic radius of a triangle 2

Wetting perimeter of a Triangle Channel formula

\(\large{ P_w =  2 \; h \; \left( 1 + z^2 \right)^\frac{1}{2}   }\)
Symbol English Metric
\(\large{ P_w }\) = wetting perimeter \(\large{ ft }\) \(\large{ m }\)
\(\large{ h }\) = fluid depth \(\large{ ft }\) \(\large{ m }\)
\(\large{ z }\) = horiz. side slope \(\large{ ft }\) \(\large{ m }\)

 

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Tags: Hydraulic Equations