My summary shows demand and flow in balance, but I am clearly losing volume out of storage over the duration of the simulation. Time steps of the demand pattern and the calculation options match and there appears to be no flow into reservoir elements
Ken,
Flow Supplied is flow to/from reservoirs and negative demands (inflows), Flow Stored is flow to/from tanks and Flow Demanded is flow leaving from demands. See: Calculation summary: Flow Supplied, Flow Demanded and Flow Stored
If your volume balance in the calculation summary is not making sense based on the results at reservoirs, tanks and demands, make sure your reporting options are set so that you are not missing out on intermediate timesteps. If tanks/reservoirs are rapidly oscillating, graphs can miss out on this detail. See this: Tank level change not corresponding to net outflow
If this still does not help, please provide a screenshot of your calculation summary and the specific results seen at one of the specific timesteps that does not look right, or provide a copy of the model for review along with steps to reproduce.
Regards,
Jesse DringoliTechnical Support Manager, OpenFlowsBentley Communities Site AdministratorBentley Systems, Inc.
I uploaded a copy of the model. The scenario I noticed the issue in is "2030 Min Day". If you trend the tanks for all time steps the loss of volume is pretty clear.
Note that I have added a new section at the bottom of the following article, with information on the "All Time Steps" row of the Calculation Summary: Calculation summary: Flow Supplied, Flow Demanded and Flow Stored
That T-18 element seemed to be the problem. Reworked the flow control valve arrangement to eliminate the need for that tank and the volume changes across the tanks looks to be in balance now.
Great, glad to hear it.
Does reporting all time steps affect the average values displayed? I.e. is it a time weighted average, or an average of the times displayed?
I did some testing and it appears the "all time steps" is an average of all the reporting timesteps (the displayed time steps), not the calculated timesteps.
Also, in a model with irregular timesteps (such as a one hour calculation timestep and a few intermediate timesteps inserted at odd times like 13.15 hours), all values are included in the calculation of the average. I did some spot checks in a test model to confirm.
I added this to the article.
I believe I had stumbled across that variance previously and why I typically avoid the "all time steps" display. Using the reporting time steps only makes it easier to see that the total applied demand is the value intended.