×
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 & Manning's n

HEC-RAS & Manning's n

HEC-RAS & Manning's n

(OP)
When coding cross sections, does Manning's n value to be used between 2 sections go in the upstream or downstream section data?  The HEC-RAS Hydraulic Manual says the expansion contraction coefficients go in the upstream section, but I can't find anything for the n value placement.

RE: HEC-RAS & Manning's n

HEC-RAS as well as HEC-2 are backwater model programs.  They use the standard step method for calculation of the
enery grade to calculate the water surface elevation.  Although the model runs up the channel, everything within the model is looking downstream. Therefore any Mannings, coefficients, flows, etc. is taken from the upstream
cross-section downstream to the next.

RE: HEC-RAS & Manning's n

Hi!
I just wanted to irreterate that HEC2 is does down or upstream depending if you select SUBCRITICAL or SUPERCRITICAL modeling.

RE: HEC-RAS & Manning's n

Actually, in the HEC-2 & HEC-RAS models, it doesn't matter if the flow is sub- or supercritical. The cross-sections still looks downstream.

The only difference is the calculation of the energy grade elevation runs downstream to upstream in subcritical & upstream to downstream in supercritical.

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