I am anlysing a collection system with a more than average amount of pressure subnetwork involved in Sewergems. I am using this system to analyze wetwell failure (power off) at the stations individually - meaning one off at a time. Currently, I am using the implicit dynamics solver as per discussions I have had with Bentley experts lately. When power goes off we all know there is filling in the wetwell, backup of water into the upstream system, storage overtime in networks and eventually overflows. My question to you all is what makes the Implicit solver advantageous in accurately predicting when and how much overflows occur for the analysis than the GVF Convex solvers or others. Secondly what are the limitations of the GVF Convex solver that makes it not applicable for this analysis. I have read a number of times on this board that GVF Convex numerical solver in SewerGEMS) is best used in systems that have complicated pumping and pressure sewers which is what I am dealing with. Thanks in advance.
Just a couple things to mention here:
We have an article that talks a bit about the different solvers:
http://communities.bentley.com/products/hydraulics___hydrology/w/hydraulics_and_hydrology__wiki/11852.sewercad-gvf-convex-solver-vs-sewergems-implicit-and-explicit-dynamic-solvers
The Convex solver uses the standard EPANET solver for pressure networks, allowing for solid stability with complex pumping situations like manifolds and pumps that cycle faster than the hydrologic timestep. However it is not intended for use with quantifying overflow, so you wouldn't be able to see the overflow in a situation like the one you describe. The Implicit or Explicit solvers are best for analyzing problematic systems or flooding since they use dynamic numerical solvers that can calculate overflow rate and several other things. The dynamic solvers also do a good job with pressure pipes and pumps, but the Convex solver tends to win there as you get more complex pressure piping arrangements.
Regards,
Jesse DringoliTechnical Support Manager, OpenFlowsBentley Communities Site AdministratorBentley Systems, Inc.