Hi guys,
I'm modelling a wastewater network on Sewergems and i'm facing some difficulties on the configuration of the weirs.I'm having two different problems. On some weirs the water due to rainfall is not discharged, continuing on the network (first and second images). On the other hand, some of the weirs present a negative flow (third image).
1. The weirs needs an outfall to make the discharge?
2. The weir is inserted on a different pipe were the wastewater goes, right?
3.The type of boundary condition of the outfall has some influence on the weir behaviour?
Thanks for the help.
Guys, anyone?
Hello,
I assume the weir in a control structure on the conduit. Is that correct? If so, and if the flow is expected to exist the system at that point, you can model this as a connection to an outfall.
Flow will only go through the conduit if it overtops the weir. You may want to graph the flow results in the conduit to see how the results change with time. The zero flow case may only be for early in the model run.
For the negative flow case, I would also graph the flow in that conduit to see how the flow changes with time. It may be that a very small negative flow is being report for some reason, but the rest of the model run is fine.
If this doesn't help, please provide us with a copy of the model and more details on exactly what the weir is representing. There are two options for sharing your model files on BE Communities. If you would like the files to be visible to other members, compress the files into a zip file and upload them as an attachment using the ‘Advanced Reply editor’ before posting. If your data is confidential, you can follow the instructions in the link below to send it to us via Bentley Sharefile. Files uploaded to Sharefile can only be viewed by Bentley.
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Regards,
Scott Kampa
Bentley Technical Support
Answer Verified By: João Madeira
Scott,
I'm sending the model. Notice that some labels and scenario names are in portuguese. The scenario with the weirs active is "Descarregadores". Please tell me if the weir next to manhole MH-76 is correctly configurated. My main doubt is if the weir has to be on the main wastewater conduit or if it is on the discharge conduit.
sewergems model.rar
Hello Joao,
I may need some additional information, but you may need to look at the elevations for the weir on conduit "CO-231". This conduit is near MH-75 (there is no MH-76 in the model, so I assume this is the area you are looking at).
This weir has elevations a little over 200 m. However, the conduit itself is a 400 mm diameter pipe with invert elevations on the order of about 180 m. This elevation discrepency may cause issues with flow in the model, once there is flow available. In the scenario reference, there is not flow from catchments because the time-intensity curve used for the storm data is zero for all time steps.
You may want to take a look at the other control structures to make sure the elevations make sense in relation to the conduit they are assigned to.
If this doesn't help, please let me know more about this weir. That may be useful in looking into the issue further.
Scott
Hello Scott,
The answer you gave me on friday was enough. I had some discrepancies on the crest elevations of some weirs. Once i've corrected them, the problem was solved.
João