Stormwater Management Model (SWMM) Information for watershed water quality, hydrology and hydraulics modelers (Note this Blog is not associated with the EPA). You will find Blog Posts and Twitter Embeds on the Subjects of SWMM5, InfoSWMM, InfoSewer, SWMMLive, InfoSWMM SUSTAIN, SWMM4 and SWMM in general.
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Oscillations in SWMM 5 and InfoSWMM
made this example to show how oscillations occur for legitimate reasons and
the best ways to test the oscillations in InfoSWMM and SWMM 5:
due to downstream obstructions, downstream mixed solutions and downstream
this case the oscillation in some links is due to the culvert comparison which
limits the flow based on the inlet equation. You can see the flow changes
if you turn on show control actions in the run manager. The program will
then show the changes in the HTML report file. The flow oscillation is
due to the water being stored at the upstream node of the culvert followed by
the excess flow going into the culvert.
to check the validity of the solution: Use a Map Display of the Link
Result Variable Link Volume. If you do a map display of the link total
volume you will see that the total volume passing through each link is in
balance. You were using a 30 minute report time step, you can see and
understand the oscillations better if you use a 1 minute report
step. In the culverts even though the flow in the culvert
oscillates the mean flow is being passed downstream – that is why the
downstream flows are constant. I am trying a different way of modeling
the steady state flow = this model does not have a continuity error but since
the inflow to the culvert is oscillating between two solutions you are getting
an uncertain flow.
Comment: A really nice water analogy for the field properties Divergence, Curl and Gradient from the Blog Starts With a Bang
....it's pretty mathematically intensive, but what's missing from most textbooks and E&M courses are physical explanations of what the mathematics means. For instance, I've started teaching about fields, and pretty much every textbook out there goes on and on about the properties of fields. They say you can do three things to fields, take the gradient, divergence, orcurl of them. (Are you asleep yet? I'm sorry!) What do these things mean? An easy way to picture it is in terms of water. If you placed a drop of water anywhere on, say,Earth, the magnitude and direction of how it rolls down is the gradient of the Earth's elevation. If you let that drop of water flow, as it goes downhill, it can either spread out or converge to a narrower stream. When we quantify that, that's what the divergence of the field is. And finally, when that water is …
Soffit Level (pipe technology)The top point of the inside open section of a pipe or box conduit. The soffit is the highest point of the internal surface of a pipe or culvert at any cross-section. The soffit is also referred to as the pipe obvert. So it is not quite the Crown of the Pipe. Here is an image I found that hopefully explains it better.
Engine Error NumberDescription ERROR 101: memory allocation error. ERROR 103: cannot solve KW equations for Link ERROR 105: cannot open ODE solver. ERROR 107: cannot compute a valid time step. ERROR 108: ambiguous outlet ID name for Subcatchment