1 / 29

Modeling Drop Structures in HEC-RAS Version 3.1

Modeling Drop Structures in HEC-RAS Version 3.1. Modeling Drop Structures. Overview Modeling a Drop Structure as an Inline Structure (Weir). Modeling a drop structure with cross-sections through the drop. Example using Lab Data. Overview. What is a Drop Structure?. Overview.

carl
Download Presentation

Modeling Drop Structures in HEC-RAS Version 3.1

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Modeling Drop Structures in HEC-RAS Version 3.1

  2. Modeling Drop Structures • Overview • Modeling a Drop Structure as an Inline Structure (Weir). • Modeling a drop structure with cross-sections through the drop. • Example using Lab Data. HEC-RAS Version 3.1

  3. Overview • What is a Drop Structure? HEC-RAS Version 3.1

  4. Overview • Why do we use Drop Structures ? HEC-RAS Version 3.1

  5. Overview HEC-RAS Version 3.1

  6. Overview HEC-RAS Version 3.1

  7. Overview HEC-RAS Version 3.1

  8. Overview HEC-RAS Version 3.1

  9. Overview HEC-RAS Version 3.1

  10. Overview HEC-RAS Version 3.1

  11. Components of Drop Structure • Control Section • Energy Dissipation Section • Adjacent Protection 3 or 4 yb Rectangular channel yb = 0.715 yc subcritical yc yb subcritical stilling basin:used to dissipate energy HEC-RAS Version 3.1

  12. Overview • How can we Model a Drop Structure with HEC-RAS ? • Inline Weir Option • Using Cross Sections HEC-RAS Version 3.1

  13. Overview • Which is more appropriate? • Inline Weir Option - probably better if just interested in elevations upstream and downstream of structure. • Using Cross Sections - better if interested in profile through the structure. HEC-RAS Version 3.1

  14. Cross-Section Locations When placing cross-sections near and through a drop structure, they need to be placed where the water surface and velocity are changing rapidly (this applies when using an inline weir also). HEC-RAS Version 3.1

  15. Modeling a Drop Structure as an Inline Weir • The standard weir equation is used: • where: C = 2.6 - 4.0 (dependent on shape) L = Length of weirH = Upstream Energy Head Q = CLH3/2 HEC-RAS Version 3.1

  16. Inline Weir - Submergence Submergence is defined as H2/H1 HEC-RAS Version 3.1

  17. Inline Weir - Submergence HEC-RAS Version 3.1

  18. Inline Weir - Cross Section Layout Inline Weir Structure 6 Cross Sections 5 3 4 1 2 Model the floor blocks as blocked obstructions. HEC-RAS Version 3.1

  19. Modeling a Drop Structure as an Inline Structure Under the “Geometric Data”click on “Inline Structure” HEC-RAS Version 3.1

  20. Modeling a Drop Structure as an Inline Structure A series of windows allow for entry of weir characteristics HEC-RAS Version 3.1

  21. Modeling a Drop Structure with Cross Sections Cross Sections Model the floor blocks as blocked obstructions. HEC-RAS Version 3.1

  22. Cross Section Layout for Ogee Shapes Drop Structure Cross Sections HEC-RAS Version 3.1

  23. Modeling Baffles in the Stilling Basin Increase ‘n’ values at baffle blocks to account for increased roughness HEC-RAS Version 3.1

  24. Example Using Lab Data • WES Physical Model Study (WES, 1994) HEC-RAS Version 3.1

  25. Example - Modeled as a Weir Cross Sections Inline Weir HEC-RAS Version 3.1

  26. Example - Modeled with Cross Sections Only Cross Sections HEC-RAS Version 3.1

  27. Example - Comparison of Two Methods HEC-RAS Version 3.1

  28. Example - Comparison Zoomed In HEC-RAS Version 3.1

  29. The End

More Related