This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

SewerCAD FM High Points

Hi,

I was able to model the force main high points in SewerCAD by placing air valves at high points, following the instructions in the link below. I have two questions:

  1. Is there a more efficient way of addressing the high points? Currently I have to add air valves manually.
  2. Would SewerGEMs require the same for the high points? I’d appreciate your answer.

 https://communities.bentley.com/products/hydraulics___hydrology/w/hydraulics_and_hydrology__wiki/2644/modeling-force-mains-with-air-valves-in-sewercad-gvf-convex-solver-tn

  • Hello Da,

    1) If you have an external data file with your air valves, you could import that using ModelBuilder. If you do not (and if you're asking how to determine where to place air valves), the best way would usually be to first run the model without air valves, look at a profile of the system and determine the first, upstream-most high point that experiences negative pressure when the pump is on. Add an air valve there, re-run the model, then look to see if there is another high point downstream of the first air valve that experiences negative pressure when the pump is on. You can then repeat this process in an upstream-to-downstream fashion. 

    2) When using the Implicit or Explicit solver in SewerGEMS, the high points would indeed be automatically accounted for (recognized by the upstream pump) without the need for an air valve. If you have a large pressure sewer model, the GVF-Convex (SewerCAD) solver tends to be more stable, but if you are able to use the Implicit or Explicit (SWMM) solver in SewerGEMS with stable results, then that may be the best option if you do not wish to add air valves. You may need to use a small calculation timestep (implicit) or Routing Step (Explicit) to achieve stable results. See: Troubleshooting unstable SewerGEMS and CivilStorm results using the implicit solver

    I have updated the wiki article you referenced in your original post, with a note about the implicit and explicit solvers in SewerGEMS:

    Modeling Force Mains with Air Valves in SewerCAD (GVF Convex Solver)


    Regards,

    Jesse Dringoli
    Technical Support Manager, OpenFlows
    Bentley Communities Site Administrator
    Bentley Systems, Inc.

    Answer Verified By: Sushma Choure