×
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

Rip-Rap: Energy dissipation calculations

Rip-Rap: Energy dissipation calculations

Rip-Rap: Energy dissipation calculations

(OP)
Good Day,

I'd like some thoughts from anybody who has had some experience in determining/calculating the amount of energy dissipation from a large sized (300mm to 500mm) angular rip-rap stones.

I have a storm sewer outlet with a rip-rap "spillway" consisting of 300-500mm anugular rip-rap at a 10% slope (not ideal, but it's what I've been given to work with).  I also know the lenght of the rip-rap spillway.  I have already determined by depth of flow, velocity, and peak outflow at the upstream end of the spillway, but would like to know the best way to determine the velocity at the downstream end of the spillway due to erosion concerns.  Would it be best to just apply Bernoulli's equation with a high loss coeffecient to account for the very "rough" rip-rap ?  If so, what would be an appropriate loss coefficient ?  Or, perhaps there are some equations or resources out there based on experimental work ?

Thanks for your time.

John

RE: Rip-Rap: Energy dissipation calculations

Hi Wterguy:
Hope this isnt too late (probably is). At least it may be helpful on the next one.  The USDA, Soil Conservation Service has all kinds of information on rip rap, conduit outlet protection, etc.  They have nomographs and charts.  I dont know if your application will fall within one of their charts, but generally mannings equation is the applicable formula (open channel flow).  they do have charts for figuring the appropriate "n" factor.  try their web site (use a search engine, eg., Google).
Scott

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