×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

HEC RAS warning msg: subcritical analysis, while trying to calculate culvert and weir flow

HEC RAS warning msg: subcritical analysis, while trying to calculate culvert and weir flow

HEC RAS warning msg: subcritical analysis, while trying to calculate culvert and weir flow

(OP)
Hi Guys,

I am new to HEC RAS and modelling a small stream about 7 km in length, but at one of the culvert section it is giving me this warning msg and I can see from the culvert output the weir flow and flow inside the culvert is not matching up with the flow. The flow should be 9.15 m3/s but weir flow itself showing more than 400 m3/s. I have attached the profile output and up/down stream cross section. For information, I was using a long cross section at the upstream as there is a huge farmers field and I was trying to see how long the water will go. Should I use the water level and ignore this warning msg? Or need to fix this problem? any suggestion? Thanks.

GS

RE: HEC RAS warning msg: subcritical analysis, while trying to calculate culvert and weir flow

(OP)
I just realize the picture didnt get uploaded! The warnings are:

1. During subcritical analysis, while trying to calculate culvert and weir flow, the program could not get a balance of energy within the specified tolerance and number of trials. The program used the solution with the minimum error.
2. During the culvert inlet control computations, the program could not balance the culvert/weir flow. The reported inlet energy grade answer may not be valid.

RE: HEC RAS warning msg: subcritical analysis, while trying to calculate culvert and weir flow

perhaps mixed flow analysis would work better

RE: HEC RAS warning msg: subcritical analysis, while trying to calculate culvert and weir flow

What are your downstream/upstream boundary conditions.
What are your steady/unsteady flow condition.

RE: HEC RAS warning msg: subcritical analysis, while trying to calculate culvert and weir flow

(OP)
Hi, I am using steady flow of 9.15 m3/s for both upstream and downstream cross section. The boundary condition is - critical depth (downstream) but I have used normal depth (downstream) and both are giving me same problem!

RE: HEC RAS warning msg: subcritical analysis, while trying to calculate culvert and weir flow

You can upload your file?

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources