Free flow flow-rate for SQUARE cross section pipes

The app returns the flov velocity and flow rate in a SQUARE cross-section pipeline in free-flow conditions
Pipe data
Design flow-rate

Pipe data   
Pipe dimensions   
Channel heightH(mm)
Channel widthL(mm)
Roughness coefficient   
Gauckler-Strickler (G-S)Ks(m1/3s-1)
% Filling rateh/H%
Design filling rateh/H( )
Flow data   
Inclinationi( )
Wet areaA(m2)
Hydraulic radiusR(m)
Avg flow speedv(m/sec)
Design flow-rateQ(m3/sec)