×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Are you an
Engineering professional?
Join Eng-Tips Forums!
• Talk With Other Members
• Be Notified Of Responses
• Keyword Search
Favorite Forums
• Automated Signatures
• 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.

# How to best model outlet structure...

## How to best model outlet structure...

(OP)
I have a pond with an outlet structure as shown in this link.. [IMG]http://i2.photobucket.com/albums/y3/itchynackers/outletjunk.jpg[/IMG]

I've been able to model it as shown here... [IMG]http://i2.photobucket.com/albums/y3/itchynackers/outletjunk2.jpg[/IMG]

but my model assumes the weir has vertical sides, when in fact it is sloped.  I've also tried to model it as a horizontal orifice.  Is there a more accurate way that I'm not thinking of?

### RE: How to best model outlet structure...

You could approximate this by using a trapezoidal weir.  Basically "flatten out" the sloped sides of the box so they form the sloped sides of a trapezoidal opening.

This will overestimate the flow in the corners to some extent, so you may want to reduce the discharge multiplier to allow for this.  But the culvert will start to control before you get too much head, so any error will be limited.
If in doubt, do a simple sensitivity analysis:  Reduce the discharge multipler and see how much difference it makes to your peak storage and discharge.

### RE: How to best model outlet structure...

As a side note, when using the sharp crested rectangular weir, the crest height is the height of the crest above the approach channel.  In your detail, this dimension appears to be 3.0ft rather than 1.0ft.  This can influence the discharge calculations.

Of course, as Peter mentions, you whould probably use a trapezoidal weir from your discription (which does not have crest height input).

### RE: How to best model outlet structure...

(OP)
I'm actually going to use a crest height of 0, since the earth will match the leading edge.  I may have to switch to a broad crested.
Also, I did a sensitivity analysis on the structure.  Minor variances with different properties.

Thanks everyone.

#### 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.

#### 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
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a partâ€™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:

• Talk To Other Members
• Notification Of Responses To Questions
• Favorite Forums One Click Access
• Keyword Search Of All Posts, And More...

Register now while it's still free!