SSA showing NaN value in bypass flow

[pmhereS5MEY]

Our project requires us to model Catch Basins (CB) on a hill. How would correctly set up my inlet to model that? I have tried to use a neenah grate and recieve a "nan" value in my bypass flow. Also why is there no bypass flow difference between curb inlet and no curb inlet? Another problem i have came across is understanding "On Sag" and "On Grade" conditions for my CB. I have been using "On Grade" because "On Sag" does not produce a bypass flow. If you could help resolve this matter that would be great! Thanks! 

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[pperales2]

Can you post a screenshot of your catchbasin?

[cdunkel]

I am having the same issue reporting "nan" for inlet intercepted and bypass in SSA 2024.

 

[fcernst]

The Neenah product rating curves only go up to 0.06 for longitudinal slope on their website., take it down to <= 0.06 just for a sensitivity test., I’m away from the computer.. curious..

then after that go back to your steep project slope and make the grate 10’ feet long .. 20 feet long..for sensitivity analysis for splash over velocity implications.. 

[matt_anderson_pe · Accepted solution]

nan is computer for "not a number."

Looks like a bug - it should capture 100% as Splash over velocity is about 9 fps for curved vane, and its only about 4.9 fps in the gutter approach.

[fcernst]

Looking at this now, your grate width is wider than the gutter width.. and you can't have that situation.

[cdunkel]

Thank you for all the responses. In this situation, the gutter width and grate width difference appears to have been the issue.

The model has been working using SSA 2019 until a new computer forced me to use SSA 2024.

I will keep all the suggestions in mind when troubleshooting in the future.

Thank you.

[fcernst]

Yes, it would be better if SSA gave a warning on that.. as other software in the industry does.

[fcernst]

To be clear this was not a bug.. it was due to incorrect User input data..

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