Part-full HGL changes

Part-full HGL changes

Throughout the development of DRAINS, various procedures have been applied to handle pressure changes at pits when flows are part-full. This has been difficult because there is little literature or guidance on this subject.

In the Lite and Full Unsteady hydraulic models that are now applied in DRAINS, the part-full flow ku factor is assumed to be the same as the specified full-pipe flow ku factor.  This is probably conservative, but helps avoid unstable changes of HGL as pipe systems change from part-full to full-pipe flow and other oscillations occur.


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