open TELEMAC-MASCARET The mathematically superior suite of solvers

Hello,

Most of the friction laws in TELEMAC-3D (except for 5) are indeed computed like in 2D ... so why Chezy ? Two reasons:
- 1st, it is a personal choice and I am used to (more than 15 years experience) fine tuning its value for model calibration; and
- 2nd, the Chezy law can be found mathematically / analytically by balancing the forces applied to a cube of water on a slope.

I have more trouble with empirical laws as we tend to forget how these were developed (such as Manning, the theory of which mainly relies on rivers in the USA).

Note that I am not trying to convince you to switch ...

Sebastien.

Hi,

Thank you for your reply!

My question was maybe a bit unclear: it aimed to ask which law, in case of willing to perform a comparison T2D-T3D, is to be preferred.
I understood that Chezy was suggested for such a comparison especially because its expression allows an identical numerical treatment in 2D/3D, compared to other laws (post 4056).

But as I understand now with your last post, Strickler (and other laws except 5) should also be treated the same way in 2D/3D.

I have indeed never modelled with Chezy (a bit hard in a 99% Strickler-wise engineering environment), but why not experimenting one day ? ...

Regards,
PL

Hello,

Indeed -- just to confirm. Only law 5 will not give you comparison and you would have to re-calibrate with a different friction when you go from 2D to 3D.

Hope this helps.
Sébastien.