open TELEMAC-MASCARET The mathematically superior suite of solvers

Hello,

Looking again at your case, I noticed that you have several overconstrained triangles in the mesh, for example in the North-West corner. It means that the 3 points of a triangle are on a border. Normally the mesh-generators should avoid this (Matisse for example had an option for suppressing such triangles). You can also rework on the mesh and split them into two triangles. The problem is that some numerical schemes are sensitive to this (and others absolutely not...). Just to make you understand, imagine that the boundary conditions impose the velocities of the 3 points of the triangle, and that you want to solve div(U)=0, this may be impossible for this triangle, as all the velocities are already imposed, which leaves you no degree of freedom.

This may explain that the diffusion step has badly conditioned linear systems. We have actually many other cases with tidal flats that raise no problem with linear systems.

With best regards,

Jean-Michel Hervouet

Hi,

I'm sorry for the late reply.
Thank you very much for this important knowledge. I have read one post before about ths:'www.opentelemac.org/index.php/kunena/16-...-for-large-t2d-model', but at that time I don't know why. Now I think I know much better from your instructions.
In fact in my large model, the shape of open boundary is almost rectangular and most of the time, mesh generated by BlueKenue always has overconstrained triangles in the corner. I will try to adjust them manually(not really sure but I guess that is why some people adopt arc-shaped open boundaries at the conrner to aviod overconstrained triangles).
Thanks again!

with best regards.
Robinson

Hi all,

I started testing a 3D model. I got "Exceeding maximum interation" error attached. Could you see what wrong with my CAS settings?

Thanks & Regards
Huy

Hi,

have you tried to shorten your timestep?

If you use an shorter timestep telemac needs lesser iterations.

Regards

Michael

Hi Micheal,

As you can see in the CAS file, my time step is only 15s. I have reduced this, but it does not work!

I guess I need to adjust other parameters, but have'nt figured out which ones?

Thanks

Huy

Hi everybody,
I'm searching for the Berre validation case of Telemac3D ('Berre Lagoon'). I have to reproduce the hydrodynamic behavior of the lagoon of Bages-Sigean. I have the impression that the example is no longer available on the v8p3 version.

Hi
As far as I know, Berre Lagoon is not a validation test case...
Moreover, I don't see it in the previous versions up to v7p0...

Regards

Hello,

I am not sure that the input files of the Berre lagoon had been provided before open source era (2010!), but for sure, since TELEMAC-3D is available via open source (2011), they are not.

Anyway, you can start from the steering file of the heat_exchange WAQTEL example. There are some useful options.

Hope this helps,

Chi-Tuan