I noticed in my StormCad model that the gutter flows at a few structures do not seem to make sense. It seems that the gutter flows do not continue to the downstream structure, even though the catch basin inlets are set to "on-grade" and the "maximum capacity" are set to the value that we want to allow in the storm sewers. What could be causing this?
In the first image below, the GU-233 should be around 440 L/s, but it's only 149 L/s.
In the second image, the GU-157 should be appox. 893 L/s, but it's only 379 L/s
What am I doing wrong? Where is the flow going?
Hi Mia,
It's hard to say for sure without seeing your model, but most likely what you are observing is caused by the way in which StormCAD's GVF-Rational solver re-calculates flow using the Rational Method (Q=CIA) based on the "controlling time" at each location. The following article explains how carryover flows are assumed to have the same time of concentration (carryover Tc / controlling time used to look up the new intensity and recalculate the flow) as the local catchment attached to the catchbasin. If you do not wish to use this behavior, you may need to toggle the "Carryover Modeling Method" calculation option.
How is the carryover Tc in a catch basin determined?
Regards,
Jesse DringoliTechnical Support Manager, OpenFlowsBentley Communities Site AdministratorBentley Systems, Inc.
You can provide a copy of the model (.STSW and .STSW.SQLITE files, zipped) using either of the two methods mentioned here: Sharing Hydraulic Model Files on the OpenFlows Forum
Hi Jesse,
I've uploaded the files.
Thanks, please provide any details or steps needed to reproduce and understand the problem.