open TELEMAC-MASCARET The mathematically superior suite of solvers

Hello,

I'm working on modelling erosion of the shorface and I needed to couple Tomawac with Telemac. I have few questions :

1/ I installed Telemac in parrallel, so Telemac2d is running in parrallel quite well; unfortunatly Tomawac doesn't. So I would like to know, when I'm coupling Telemac2d with Tomawac, if there is a way to run Telemac2d in parallel even if Tomawac can't ?

2/ Then I have some problems understanding how I can affect friction coefficient to my model, because I'm not in a case of a chanel. So It looks wierd to add a manning (or other) coefficients to my domain. Is there a friction coefficient for a none-chanel domain in Telemac2d?

3/ Finally, I tried to run my model with different boundary counditions. Result_CL544 is the result of the simulation with prescribed Height and free velocity and Result_CL566 with prescribed Height and prescribed velocity. Regarding the results Result_CL566 looks more physical. But I thought that Tomawac was only calculating water height values so a boundary condition 544 has more sense for me. How do I have to parmeter my boundaries ?





Regards,
Rémi

Hello Rémi,

Actually Tomawac parallelization is being rebuilt and it will be available in the next release. What you can do as a tentative solution is to use the developping version (on the trunk ), The feedbacks are until now very positive and it should work for your case.

For your second question: of course you can affect friction coefficient independently of the shape and the nature of your application. I invite you to have a look at the user manuel, in which there is a whole section dedicated to the ways to introduce and to manage the friction.

I'm not the most skilled person to give advices on your third question, however, a 544 condition seems the more physically accepted. I hope that other Tomawac users will complement my answer.

I hope that it was helpful.

With my best reagrds

Riadh Ata

Thank you for your answer Riadh,

I'm going to work on installing the developping version and affecting the friction coefficients. I will also look for some information and studies on the coefficients I should use for the gravel surface of a steep slope.

I agree with you 544 seems the more accurate boundary condition for my model. But as you can see on the picture, there are some strange velocity phenomena near the boundary.Do you think it could come from the value of the water height near the coast (and so the waves)? Because Telemac2d calulates the velocity thanks to the water height, am I right ?

Anyway, I'm also going to look for some information on the Tomawac section.

Thank's again
Rémi Dumasdelage.

Hello Rémi,

I am not a TOMAWAC user at all, but I will try to give you some hints. By reading the TOMAWAC manual (6.1) and the LECLIM_TOMAWAC subroutines, it seems that only the first column and the last two columns of the BOUNDARY CONDITIONS FILE are read. The standard of the rest of TELEMAC system should have been kept to be coherent with it. So, in your case, using 5 4 4 or 5 6 6 code for TOMAWAC should give the same results.

I do not know so much about the coupling between TELEMAC and TOMAWAC, but with a TELEMAC point of view, using 5 6 6 code in the boundary conditions file for a coastal case with the Thompson conditions often gives more physical solutions, in particular when the tidal wave enters the domain (the problem is then well posed, contrary to when prescribing the elevation in this case). Anyway, far from the open boundaries, the results are not too different in general.

Hope this helps,

Chi-Tuan

Hello Chi-Tuan,

You're right, using 544 or 566 doesn't change the Tomawac results.

But if I'm using a boundary condition of 566 on my study area, I need to prescribed velocty values. By default it will be 0.0. I think these values are not physical because it means that on the limits of the domain, I will have a velocity equal to zero. That's why I got this vortex on the left side of the study area (I think).
So as you said, I suppose that 566 code is okay when you have values of the tidal waves velocities... In my case the tidal effect can be neglected.
So I should put the 544 code for the boundary conditions (at least on the left side of the study area)? But as you can see the results are not realistic (second picture). Don't you think it could come from the value of the water height (implied by the waves simulation of Tomawac model) ?







Thank's for your help,
Best regards,
Rémi

Hello Riadh and Chi-Tuan,

Thanks to your different advices I finally solved my problems, about the boundary conditons.

I added the key word: 'OPTION FOR THE LIQUID BOUNDARIES=2' on the Telemac2d steering file. With this option, I'm using Thompson conditions which allows to calculate acurate values of velocity at the boundaries.
So on the picture,my boundary conditions are 544 (on the sea side)and I finally get physical results.



Thank you again,
Best regards,
Rémi.