Hello Everyone and Happy Holidays. I was wondering if someone could help explain something for me. In a model when viewing the flex table for junctions the value in the "Demand" column is different than the demand shown in the "Demand (Base)(gpm)" column in the "Demand Collection". Can anyone explain the difference between the demands entered as a Demand Collection and the Demand column value in the flex table?
Thanks
Walter,
That is the total demand being calculated at the junction vs. Demand collection, which is the demand that you have input at the junction. In most cases those numbers should be the same after you take into account any multipliers for the numbers, unless there are some user notifications that need to be troubleshot in the model.
This wiki explains where to find the definition of a property in case you have questions in the future
This wiki might help you troubleshoot why your demands do not match what you have entered in the model
Mark
Answer Verified By: Walter Medley
If you are running an EPS (Extended Period Simulation), the calculated "Demand" field will account for any pattern multipliers if you have a pattern assigned to the base demand. Patterns enable you to vary the demand over the course of the simulation, and the way that the program computes the overall demand for a particular timestep is different depending on whether you select continuous or stepwise, as explained here: Demand calculation with Continuous vs Stepwise patterns
The second link that Mark provided points out the demand adjustment calculation option which can further adjust the calculated demands if desired. I added a note to that article about the pattern multiplier behavior for an EPS.
Regards,
Jesse DringoliTechnical Support Manager, OpenFlowsBentley Communities Site AdministratorBentley Systems, Inc.
Thank you Mark for the very useful information.
Thanks Jesse for your reply. After reading Marks comments I delved into the pattern multiplier and did find that was what I was seeing. I ran a steady state with EPS snapshot and set the equivalent hydraulic time step to as close to a 1.0 multiplier on my pattern. My demands are now adding up so I can now verify the accuracy of the demands that were entered for each junction in my system.
Thanks to Mark and Jesse.