I have a riser with a weir that discharges to a triple box culvert. Do I put all three at elements in one outlet control structure? I put the downstsream id for the riser and the weir as the culvert. Then I put "free outfall" as the downstream id for the culvert. But then you have to do a tailwater condition for the entire structure, so I generated an elevation-flow curve for the culvert in a separate program (HY-8) and then I put that in as the tailwater condition for the entire structure. Is that right? Something is wrong b/c my estimate peak flows are ridiculous compared to my 100-year inflow that I entered in for the catchment area (100,000 cfs vs. 1,000 cfs). Any thoughts on what I did wrong?
See below thread:
http://communities.bentley.com/products/hydraulics___hydrology/f/5925/t/64355.aspx
The riser component has a built-in weir, so there is no need to enter a separate weir component in your outlet structure. When water spills over the riser crest, it passes over the weir component of that riser, and into whatever you enter as the downstream ID. So, in this case, you would have two items in your composite outlet structure, a riser and a culvert. Configure the weir in the riser component and set the downstream ID to the culvert. For the culvert, enter 3 barrels, with a downstream ID of "tailwater".
If the culvert discharges into a river or something similar which could impose a tailwater, you could configure that in the tailwater section of the composite outlet structure itself. If the elevation-flow curve you mentioned is for the same 3-barrel culvert that you already entered in the composite outlet structure, you would be double-counting that element. You should instead either only have the culvert component, or omit the culvert component and use the elevation-flow curve as a tailwater condition of the composite outlet structure.
For an example, please see the "Riser.ppc" sample file, located under \Program Files\Bentley\PondPack8\Samples\ . In the composite outlet manager, you will see two composite outlets. Both of these example outlets illustrate a perforated riser that discharges into a 3-barrel culvert. One is a standpipe type of riser (circular top) and the other is an inlet box (rectangular top).
You may also benefit from following the quick start lessons in the help documentation or looking into our training sessions.
I hope this helps. Again, if you have any further questions or problems with your outlet, I would encourage you to contact technical support.
Regards,
Jesse DringoliTechnical Support Manager, OpenFlowsBentley Communities Site AdministratorBentley Systems, Inc.