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lclements

Losses for 1D culverts

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Dear all,

I am modelling a circular culvert and trying to understand the relevant form loss coefficients and inlet/outlet losses.  Specific queries are:

- How would I best represent a trash screen on the upstream face of a circular culvert?

- Is it best to account for bends along a culverted length using increased Mannings or a form loss coefficient?

- What are appropriate form loss values?

There appears to be limited guidance in the literature regarding losses at culverts- is there any particularly relevant guidance that may be of benefit to me?

 

Thanks!

:-)

 

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Hi lcements, 

Thanks for posting this query. Please see below some comments. If anyone else out there has some new literature on this topic we'd love to hear about it.

- How would I best represent a trash screen on the upstream face of a circular culvert?

There is some guidance on form losses provided in the previous thread below.

 

- Is it best to account for bends along a culverted length using increased Mannings or a form loss coefficient?  

You are best  to apply bend or drop losses using the Form_Loss attribute of the 1d_nwk layer. This applies the energy loss appropriately for a 'minor' loss using K* V2/2g. You can also use the pBlockage attribute in your 1d_nwk if you believe there will be deposition of debris on the inlet during a flood event. AR&R provides some guiding information on debris blockage here: http://www.arr.org.au/revision-projects/project-list/project-11/

- What are appropriate form loss values? 

The loss values will depend very much on the structure and configuration. As described above the Queensland Urban Drainage Manual may provide some guidance. https://www.dews.qld.gov.au/water/supply/urban-drainage-manual

There is also the Concrete Pipe Association of Australasia's Design Manual which is a great document:  http://www.cpaa.asn.au/images/publications/engineering_guidelines/cpaa_design_manual_hydraulics_jan13.pdf

There is also a range of documents published by the US Federal Highways Culvert Design Manual: http://www.fhwa.dot.gov/engineering/hydraulics/culverthyd/culvert.cfm which maybe of interest. 

Hope this helps. Other posts very welcome!!! Cheers Mitch.

 

 

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