Manning Equation

Written by Jerry Ratzlaff on . Posted in Fluid Dynamics

Manning equation applies to uniform flow in open channels.

formula

\( Q =  v_aA  =   \frac  { k }  { n }    \left( \frac {A}  {P} \right) ^{2/3}   S^{1/2} \)

Where:

\( Q \) = discharge flow rate

\( v_a \) = average velocity in a channel, culvert, or pipe

\( A \) = average area in a channel, culvert, or pipe

\( k \) = unit conversion factor (\(k = 1.49\) English units ft/sec) (\(k = 1.0\) SI units m/sec)

\( n \) = Manning roughness coefficient

\( P \) = wetted perimeter

\( S \) = channel slope

 

Tags: Equations for Flow Rate