Tuesday, May 16, 2017

Putting Wormhole Culverts to the Test

Written by Krey Price  |  Director, Surface Water Solutions
Copyright © The RAS Solution 2017.  All rights reserved. 


The original post about “Wormhole Culverts” received thousands of hits, and many HEC-RAS users are now applying this method regularly in their models; but how valid are the hydraulics over the full range of open channel flow, pressure flow, and weir flow? Given the amount of use they are getting, it’s high time to put wormhole culverts to the test!

This test run assesses wormhole culverts against other approaches for modelling hydraulic structures in 1D and 2D model reaches.

The results show very similar water surface profiles between the various methods. The wormhole method provides the ability to correctly display terrain data for roadways and bridge decks in viewing plan and profile results.

While coupled 1D-2D reaches would still be required for detailed bridge designs in HEC-RAS, wormhole culverts appear to be a viable means of accounting for bridges and culverts with substantial terrain detail between the inlet and outlet that is subject to 2-dimensional flood flows.


Read more about the model setup and results here.


10 comments:

  1. Is the Z-shape for the Wormhole Culverts mandatory ? Or is any shape possible ?

    Philippe

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    Replies
    1. I guess not. It needs to double back on itself so that the outlet is on the correct side of the connection line. Besides that, I think you're free to make it whatever shape you want. What shape did you have in mind, and why?

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  2. Thank you for your answer. No particulary shape in mind, just a question. Is there a significative impact if the outlet is on the wrong side ?
    I think about wormhole culverts to inject flow at a specific place in a 2D-model. Do you think it could possible to link a storage area outside the 2D area with this method ?
    Philippe

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    Replies
    1. If the outlet is on the wrong side, yes, it would be a significant impact. I would try to avoid this. Wormhole culverts can be used to inject flow on the interior of a 2D area. But instead of linking it to an external storage area, you have to create some "dummy" terrain storage inside your 2D area . Preferably in a place where you'll have no flow. Then link up your wormhole culvert from that dummy storage to the point where you want to inject flow.

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  3. Very cool workaround. Do you know approximately when the next release is scheduled, or if the next release will incorporate XS creation/editing capabilities in RAS (GeoRAS replacement)?

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    Replies
    1. I would guess about 1 to 2 years from now. And yes, HEC intends to do away with GeoRAS and have all geometry preprocessing done within HEC-RAS for the next release.

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    2. so 1 to 2 years before 5.1 is out? That is interesting as the HEC UK training courses states they are showing 5.1 in July.

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    3. All I can tell you is what I've heard. Maybe UK is getting a sneak peak into new features in 5.1.

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    4. Thanks Chris... Whenever I do my daily refresh of your blog I am always hoping for impending news of the 5.1 release. Good to know what the actual timeline is. :)

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    5. You're welcome! I'll be sure to announce the new release as soon as it comes out.

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