Hydraflow Skimmer Model

[NC-Engineer]

I need to model a detention basin with a skimmer. Is this possible with Hydraflow.  

Thank you,

Michael

[Civil3DReminders]

I suspect the skimmer is on an outlet wier? If so I guess you'd have to adjust the weir coefficient to account for the flow restriction from the flow or use a value from the manufacturer. 

[NC-Engineer]

Yes, the skimmer is a dewatering device that attaches to the bottom of the outlet structure and floats on the surface. They are used in sediment basins to drain the clean water from the top while allowing the suspended solids to settle to the bottom. The skimmer orifice sits a few inches below the surface dewatering the pond from the top. This enables the skimmer to rise and fall with the water elevation. Adjusting the coefficient is not a problem. The skimmer should be modeled as an orifice located at the bottom of the pond with constant head and flow since head is constant. I need to know how to set up an orifice with either constant flow out (taking head out of the equation) or designating a constant head.

[Hidden_Brain · Accepted solution]

i think in Hydraflow you have an option for a known constant outflow from a pond, that you can use to simulate the skimmer orifice that will move up and down to hold a constant head and release a constant flow.

The option is called USER DEFINED FLOW in the pond window outlets tab (table at the bottom). You cannot have a UDF for stage zero, but can set the known Q value of your skimmer for rest of the stages. you can calculate (externally) the known Q of your skimmer using orifice or weir equations as appropriate.

[phamerZHSLM]

How do you enter the discharge from the skimmer in the user defined discharge column.  When I attempt it, it doesn't let me input anything.