Hydraflow - Elliptical Pipe

[JJRengineer]

We are working on a project in which we are connecting our proposed storm sewer into an existing downstream storm sewer.

We are using Hydraflow for modeling purposes.

The existing storm sewer is an elliptical pipe and everytime I "run" the program I get different values for the Hydralic Grade Line "HGL".
They increase everytime the model is ran.
For example, when ran first time the HGL value for one of the pipe segments = 106.5, when ran a 2nd time the HGL for same pipe segment increases to 108.5, 3rd time HGL = 110.5 .....and so on.
The starting HGL remains the same in each model and everytime it is ran so that is not the problem.

I used the same model and switched the elliptical pipe to an equivalent circular pipe and the model gives me the same HGL value everytime I run it; as expected.

My question is whether there is a "bug" in the Hydraflow software in which elliptical pipes are not modeled correctly or why are different HGL values calculated each time the model is run when elliptical pipes are modeled?

Anyone experience something like this?

Thanks

 

[beej67]

On a scale from 1 to 10, where 1 is "feature" and 10 is "bug," I give that a 13.

Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East -

http://www.campbellcivil.com

 

[chicopee]

Perhaps the program is not designed for elliptical pipes. Aabout running the program on equivalent circular piping whereby the equivalent dimensions would be based on a hydraulic radii and comparable friction losses.

 

[mddeng]

I would "fake" it out and use an equivalent round and see what happens.