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Inlet Capture Efficiency Calculations

Greetings,

As understand from the below link, Bently SWMM engine calculates the Inlet capture efficiency first and then flow captured will be calculated.

https://communities.bentley.com/products/hydraulics___hydrology/f/haestad-hydraulics-and-hydrology-forum/200180/on-grade-inlet-with-swmm/597699#597699

We are working on storm Inlet modelling, need to understand the Inlet capture efficiency.

Could any one please explain to understand more on this?

regards

Ganesh Bala S

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  • Hello Scott,

    Thank you for your reply

    Could you please share the equations adopted for in SewerGEMS for calculating the Inlet interception flow & efficiency and also if we locate the Inlet in SAG the efficiency result is shown is not applicable - please provide.

    Refer below image for the Inlet properties used in our model.

    Regards

    Ganesh Bala S

    Regards

    Ganesh Bala S

    Design Engineer

    Khatib&Alami Engineering Consultants Pvt. Ltd.

  • Hello Ganesh,

    Page 4-43 (and likely other pages around there) of the HEC-22 manual appears to have the relevant info for on grade inlets.

    For an inlet in sag when using the Explicit solver, the capture efficiency is reported as N/A. This is because the flow captured is determined based on the depth of the flow stored, and not the inflow to the inlet. If you highlight the Capture Efficiency field in the Properties display, you can see this in the explanation of the field at the bottom of the Properties display.

    Regards,

    Scott

  • Hi Scott,

    Thank You,

    Agreed with you, also have worked out the equations in HEC-22 but couldn't match with our hydraulic model results exactly.

    We has to show the calculations to match with hydraulic model results. Could you please share any worked out examples in brief for both On Grade & Sag conditions other than the examples from HEC-22.

    Inlet details as shown in above image

    Regards

    Ganesh Bala S

    Regards

    Ganesh Bala S

    Design Engineer

    Khatib&Alami Engineering Consultants Pvt. Ltd.

  • This is because the flow captured is determined based on the depth of the flow stored, and not the inflow to the inlet

    Hello Scott

    1-Why Inlet in Sag is not calculated based on "inflow" ? 

    2- If the capture efficiency is always 100%, that should be reported.

    Regards,

    Mohamad

  • Hello Ganesh,

    Do you have an example you can provide, of both the model and hand calculations? This link has information on sending the files.

    Regards,

    Scott