How can I model 2 individual riser outlet structures in Hydraflow 1

[freemon]

I have a pond with two separate 4-foot diameter riser structures with their own outlet pipes. They each have a square weir cut into the top and then the top will be open and act as the overflow weir.
I simply modeled this as an 8-foot diameter structure with all the particulars and modeled it as a multistage device. The reviewer says it isn’t the same.
Anyone got a better approach for me in Hydraflow?? Thanks!

 

[psmart]

I'm not sure how you handled the two outlet pipes, but an 8-foot diameter riser has a perimeter (weir length) that is four times as long as a 4-foot diameter - not twice.


Peter Smart
HydroCAD Software

http://www.hydrocad.net

 

[RWF7437]

Are the overflow elevations of the two structures the same ?
Are the outlet pipes the same and at the same elevation ?

 

[Drew08]

Develop the stage-discharge rating curve for each spillway separately in a spread sheet model using basic weir-orifice-pressure flow equations. Sum the two rating curves, and enter into the model as a user defined discharge.

USBR: Design of Small Dams is a good starting refernece.

http://www.usbr.gov/pmts/hydraulics_lab/pubs/manuals_monographs.html

 

[freemon]

the overflow elevations of the two structures are the same as are the outlet pipes. They are twin structures.
I did run the pond thorugh one 4' stucture and can see that the stage discharge are all exactly half of the 8'.