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Volume Balance

Fri, 04/11/2008 - 3:47pm — nick
I have an application with an unacceptable volume balance error (21%). What things can be done to decrease the error in the volume (and energy and mass) balance? I have tried a multitude of things but have had only minimal success. Thank you for the help.
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Hydrodynamics
Fri, 04/11/2008 - 4:19pm — chris

Hi Nick, What kind of system is it? River, lake or reservoir? If your model has multiple branches, does the error occur in a specific branch? If you haven't already done so, the first things I would try would be reducing the time step criteria DLTMAX and/or DLTF in the control file. When doing so track the error and see if it is being reduced - that can help you know if you're on the right track. Also, reducing DLTMIN can sometimes help. chris
Mon, 04/14/2008 - 11:15am — nick

Chris, Thank you for the response. The system is a reservoir with two branches. The error is more significant in branch 1. I was able to get closer to an acceptable error by modifying the bathymetry and smoothing out some areas with rough transitions. Reducing the timestep, as you suggested, further reduced the overall volume balance error to 0.2E-6. Though this still isn't within the recommended range of 1E-8 to 1E-13 the total error is only 10 cubic feet over 2.5 years. Thank you again for your time and suggestions.