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Orifice in SewerGEMS

Hello,


Can someone pls draw a sketch of SewerGEMS orifice idea?

I want to use it as a Start Control Structure in pipe in order to slow down discharge from sewage system in order to reduce the impact on the river.

I want to model an circular orifice (dia 600 mm) at the start of a 1600 mm pipe i want it to look like this - see attached file.


Regards Jarek

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  • Hi Jarek, 

    In SewerGEMS the orifice in the start and stop control structure has two options. One of those options is a for a side orifice and the other option is for a bottom orifice. I have sketched out what they look like in the picture below. One way that you can model this is by figuring out your flow for given depths using the orifice equation and then use a depth vs. flow control structure to create a rating table. I'm currently looking to see if there is another way to model this for you too.  

    I hope that helps.

    Regards, 

    Mark

    Mark

  • Hi MPachlhofer ,

    Thanks for a reply & a nice sketch. It looks that none of the shown orifices matches exactly my problem.

    What i am looking for is a kind of weir (perpendicular to the pipe axis) with a crest situated very high (above the pipe top) and a circular hole at its bottom (see sketch).

    In the meantime i will try to create a curve depth/flow for a side orifice as you have advised and yes I i know it want be exactly the same :) as it has a different coefficient then the one I am looking for :)

  • Jarek,

    I think there was a misunderstanding with my last reply. Using a depth vs. flow curve will allow you to model an orifice that is inline (parallel) with the flow direction as it appears you're looking for. In other words, the orifice will not be a side orifice, but act more like an orifice plate, which is what it sounds like you are looking for. You can see an image of how an orifice plate functions on this website: http://www.wermac.org/specials/orificeflowmeter.html

    Regards,
    Mark

    Mark

    Answer Verified By: Sushma Choure 

  • MPachlhofer,

    Yes You are right :)
    Anyway in the meantime I've changed my mind and switched to a weir and a manhole with a by-pass pipe of the required diameter.

    Regards
    Jarek

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