Intellisolve's Hydraflow VS Engenious StormSHED 3

[kswanson]

Hi, I need to get this situation resolved. I need to verify a stormwater conveyance analysis and I'm puzzled as to why the two models provide different flow capacity values. A consultant provided me a Hydraflow conveyance model that shows "Cap Full" (Capacity Full I presume?) values are substantially larger than "Full Q" values I modeled in StormSHED. The Q values that actually flow through each reach are very close for both programs, but the max capacity values dictate whether or not the conveyance model passes the design criteria. His model passes because his capacity values are so high that it will never overtop, but my StormSHED model says that it fails because my capacity values are much lower. Here are the capacity values for each reach.
StormSHED (cfs) Hydraflow (cfs)
17.74 32.65
11.45 25.34
6.28 5.25
2.9 5.33
6.4 5.35
3.25 7.54
3.68 6.74

It was brought to my attention that StormSHED is a gravity- based program so when it computes pipe full capacity, it's based on gravity, not some surcharge. How does Hydraflow compute "Cap Full" values? I don't have a copy of the program so I can't research it. Thanks so much for your time.

 

[kswanson]

I did mislabel the StormSHED and Hydraflow columns. Thanks for pointing that out to me. The labels need to be switched. And yes, the reports do indicate that the pipe is 36" diameter. I had to retype the information in Word, so mistakes do happen. It would be nice to have both a hard copy and a digital copy of the report so I could copy and paste the data into Word.

It would be nice to find out why the Full Q and Cap Full values differ so much with both programs. Any ideas as to why this happened?

 

[bltseattle]

Stormshed accounts for tailwater conditions, as I recall, which would yield lower pipe capacities than free-flowing pipe outlets - especially since you have some very flat pipes (S<0.5%)

 

[mjwoodruff]

I read in the Civil 3D stormwater discussion group that Hydraflow recently updated it's modeling of pipe flow. I would check that forum, because people were getting different flows even between version of Hydraflow.

Michael

http://www.revisionblock.com

Import Hydraflow Into Excel