Notifications about conduits operating under pressure or being in the Preissmann slot

  Applies To 
  Product(s): SewerGEMS, CivilStorm
  Version(s): 08.11.XX.XX, 10.XX.XX.XX
  Area:  Modeling
  Original Author: Scott Kampa, Bentley Technical Support Group

Problem

What does the following user notification mean:

"One or more junctions are pressurizing all conduits; or conduits are in Preissmann slot at this location for this time-step."

"Conduit is operating under pressure."

OR

How does the implicit solver (SewerGEMS) transition from pressure flow to gravity flow and vice versa? 


Problem ID#: 67974

Solution

This message is generated when a pipe's HGL is above the top elevation. The numerical solver does not distinguish between conduits and pressure pipes in the model, so this message may be generated when pressure pipes exist in the system. You can view profiles of the system to see the HGL across the system, as a way to see any gravity pipes in the model are surcharging.

For more information on Preissmann slot method used in this situation, there are topics about this in the Help documentation. Search for the term "Preissmann slot" or "Pressurized Flow".

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