open TELEMAC-MASCARET The mathematically superior suite of solvers

Does anyone have an idea of typical values for the head loss coefficients (CE1, CE2, CS1 and CS2) for siphons in the CULVERT DATA FILE?

Olivier.

There are plenty of good references you might find for this. Beyond your hydraulic textbooks....

In North America you might rely on the US Department of Transportation. Here's a link to an OLD scan of one of their documents:
www.dot.state.mn.us/bridge/pdf/hydraulic...nual/chapter%205.pdf

Or the Handbook of Steel Drainage & Highway Construction Products:
www.cspi.ca/node/158
(you used to be able to get this book for free from pipe distributors, but perhaps I'm aging myself if this is no longer true....)

CE might range from 0.2 to 0.9 depending on headwall characteristics.
CS might typically be 1.0, again depending on conditions.

But these values are, as always, guidelines. Always check your model and be sure it's behaving properly!

Thank you for the links. By the way, the handbook is indeed free to download if you do it chapter by chapter.

I would have another question about siphons though. As I come from marine modeling, this matter is brand new for me.

In the TELEMAC-2D user manual (release 6.2, section 10.2), it seems to me that the discharge parameterization lacks a squared root somewhere (it is present in the French version of the manual). As is, it seems not dimensionally correct.

Anyway, below, it is suggested that the linear head loss coefficient L12 may be evaluated as Lambda * L / D, where L is the length of the pipe, D is the diameter of its cross section and Lambda is a friction coefficient.

If I am not wrong, Lambda is supposed to be dimensionless, which is quite different from the Chézy-Manning-Strickler friction coefficient family, with which I am more familiar.

Does anyone can give me typical values for this coefficient Lambda as well? I know I could take a look to the above-mentioned references, but you could save me a lot of time...

You are correct, the equation for culvert discharge in Section 10.2 is missing the square root. Fortunately, the equation is correctly applied in the SIPHON.F routine.

I solve for Telemac's friction loss L12 by back calculating from Mannings equation. This is what the US DoT guideline (in my link above) is doing in their equation 5.2c for friction headloss, except they've solved for the Mannings equation using Imperial units.

L12 = (n^2*L)/(R^1.33)

Thank you for your help!