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

Do you use discharge multiplier if storage has mutliple items?

Do you use discharge multiplier if storage has mutliple items?

Do you use discharge multiplier if storage has mutliple items?

I am modeling a subdivision with rain gardens to treat roof runoff. I combined the roof surface area from multiple lots (let us say five). So in my pond (rain garden), I enter five separate rain gardens for storage, each which will infiltrate and have a weir overflow. On the outlet tab, I have exfiltration (wetted perimeter) and sharp-crested rectangular weir. If I do not use the discharge multiplier for the rectangular weir I get run errors that things have WAY overtopped. So, in this situation with five identical storage lines (rain gardens) do I use the discharge multiplier and set it to 5? It fixes the run error but not sure if this is correct modeling.

Also of note, the infiltration seems to be fine but maybe that should be set to Discharge Multiplier of 5, too?

RE: Do you use discharge multiplier if storage has mutliple items?

If you want to simulate 5 weirs then you need to set the weir discharge multiplier to 5. The exfiltration is a bit more complicated. If you're using the constant flow option, then you do need to set the multiplier to 5. But if you're using a constant velocity, the exfiltration is automatically applied to the TOTAL storage area, which you've already increased 5x, so the exfiltration multiplier should stay at the default of 1, otherwise you'll be making a double adjustment.

Peter Smart
HydroCAD Software

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


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