×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Contact US

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!

*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

Calculating additional velocity due to gradient

Calculating additional velocity due to gradient

Calculating additional velocity due to gradient

(OP)
Hello all,

I hope that you can help me with a simple problem. Hydraulics is not my thing and I'm probably overthinking things.

I have a 1.8m x 32.5m smooth concrete surfaced footbridge which is now inclined an additional 1.5 degrees; what I would like to know is how does the slope affect the water velocity and what is the equation required to show this?
Essentially I need to ensure that the current spitter pipes are of sufficient capacity to handle the inline.

Many thanks,

Michael

RE: Calculating additional velocity due to gradient

(OP)
I've been looking into this an I think that the Manning equation is probably the option that I should use. Would anyone be able to confirm this please?

v = kn/n R2/3 S1/2

RE: Calculating additional velocity due to gradient

Manning's Equation is one appropriate method to compute the velocity of flowing water. The slope should be in (ft/ft) or (m/m) and should represent the longitudinal slope of the conveyance structure you are evaluating. There are numerous books with roughness coefficients (n) that you can use to get your roughness from and the "R" is hydraulic radius (Area/wetted -perimeter). You did not provide enough information, however. What velocity are you seeking the velocity on the bridge or under the bridge? Forgive my misunderstanding; but, what is a spitterpipe?

RE: Calculating additional velocity due to gradient

(OP)
gbam,
Thank you very much for your reply. I purposely didn't include all of the information as I believe certain factors weren't required for my query. I can see now that you may have thought that the structure possibly spanned over water, it doesn't.
The velocity that I was seeking for was the storm water passing across the surface of the footbridge due to the increase in elevation at one end.
To answer your final question, a spitter pipe is essentially a pipe to discharge water. Please see attachment.
MDBris

RE: Calculating additional velocity due to gradient

Thanks for the clarification of a spitter pipe.

What flow rate are you using to compute the velocity? Was that computed using rainfall runoff processes?

Oh, I should clarify that the slope used in Manning's Equation is the slope of the Energy Grade; however, for normal flow the slope would be the slope of the channel.

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! Already a Member? Login


Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close