Profile Issues

[Anonymous]

I finally have my model up and running, and during execution I get errors about 1/2-way through the simulation. When browsing through my profiles, my profile appears to be “flattened” with the green-dashed “EG” line being waaaay off the chart on a few cross sections. I took a screen shot of the system profile view to get some opinions. Any idea what’s going on here? Is the “EG” line symbolic for energy grade?

Here’s the image:

free photo hosting

[Robert]

Hi Jonathan

Theory:
Enegry grade line have to decrease gradually along of river. EGL or EG equals water surface head + velocity head. You would look a law conservation of energy!

Your issue can be a result:
– enough cross sections (Geometric Data – Tools – XS interpolation)
– HTAB computation points (Geometric Data – HTab Parameteres: Increment=0.1 and Points: 100)

I think, that your issue is in the HTAB!!!

I recognize to study very good articels by Ch. Goodell (see you):
http://hecrasmodel.blogspot.sk/2009/06/energy-grade-line-problems.html
http://hecrasmodel.blogspot.sk/2009/02/crazy-energy-grade-line.html
http://hecrasmodel.blogspot.sk/2009/02/crazy-energy-grade-line.html
http://hecrasmodel.blogspot.sk/2013/10/stabilizing-dynamic-unsteady-hec-ras.html

In the case of the next questions you can write me
Have a nice day!
Robert

[Anonymous]

I saw that Robert had provided links to some docs regarding how to diagnose and fix these problems. My guess is that your model is going unstable because of zero depth or supercricitical flow. Would like to see your data.
Michael

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