Force on Weir

[WAstruc10]

For a "sutro" (or proportional) weir, how do you calculate the force on the weir "blades"? This is an outlet for a small lake, into a channel. Is it simply the hydrostatic force, assuming the water is flowing pretty slowly on the high side, or are there significant "nozzle" type or other forces to be dealt with due to hydrodynamic effects? Thanks-

 

[Ron]

Hydrostatic upstream and drag off the downstream face.

 

[WAstruc10]

Thanks ron...is there someplace you could point me for figuring out the downstream face drag?

 

[bimr]

You can probably estimate something from Bernoulli's equation:

V*2/2g + H = Head of water.

H = water head or psi =FT water/62.4, V = Stream Velocity

http://www.engineeringtoolbox.com/weirs-flow-rate-d_592.html