open TELEMAC-MASCARET The mathematically superior suite of solvers

Hi,

I struggle for now 2 weeks trying to stabilize a telemac2d model (version v8p2).
This model runs well for all the hydrographs that I simulate except for the higher recurrence interval (500 years) for which a breach opens in the left levee. It seems that this breach provocates instabilities that I tried to solve through various approaches (decrease in the time step, progressive opening of the breach instead of instantaneous...). Unfortunately, I still don't manage to stabilize the model which becomes unstable once the breach opens, creating a massive entrance of flow from the first boudary segment (444 type). I provide the model in case you have time to check it, with the boundary conditions.
Download link: www.grosfichiers.com/ptkkCEK6Unu
Would you have any idea on the way I could avoid such instabilities?

Best regards

Hi Thetiot,
I dont have time to check your model in detail, but it reminds me of one model that I did last year. You can try the key word and see if it works:
TRAITEMENT DES HAUTEURS NEGATIVES = 1 (instead of 2)


Hope that helps,
Lan Anh

Dear Lan,

Thanks for your answer.
I tried your suggestion but it creates an error at the inception of the calculation:
PLANTE: PROGRAM STOPPED AFTER AN ERROR
RETURNING EXIT CODE: 2
application called MPI_Abort(MPI_COMM_WORLD, 2) - process 9

job aborted:
rank: node: exit code[: error message]
0: SCE-1802.sce.local: 2
1: SCE-1802.sce.local: 2: process 1 exited without calling finalize
2: SCE-1802.sce.local: 2: process 2 exited without calling finalize
3: SCE-1802.sce.local: 2: process 3 exited without calling finalize
4: SCE-1802.sce.local: 2: process 4 exited without calling finalize
5: SCE-1802.sce.local: 2: process 5 exited without calling finalize
6: SCE-1802.sce.local: 2: process 6 exited without calling finalize
7: SCE-1802.sce.local: 2: process 7 exited without calling finalize
8: SCE-1802.sce.local: 2: process 8 exited without calling finalize
9: SCE-1802.sce.local: 2: process 9 exited without calling finalize
10: SCE-1802.sce.local: 2: process 10 exited without calling finalize
11: SCE-1802.sce.local: 2: process 11 exited without calling finalize
12: SCE-1802.sce.local: 2: process 12 exited without calling finalize
13: SCE-1802.sce.local: 2: process 13 exited without calling finalize
14: SCE-1802.sce.local: 2: process 14 exited without calling finalize
15: SCE-1802.sce.local: 2: process 15 exited without calling finalize
Traceback (most recent call last):
File "C:\opentelemac-mascaret\v8p2\scripts\python3\telemac2d.py", line 7, in <module>
main('telemac2d')
File "C:\opentelemac-mascaret\v8p2\scripts\python3\runcode.py", line 271, in main
run_study(cas_file, code_name, options)
File "C:\opentelemac-mascaret\v8p2\scripts\python3\execution\run_cas.py", line 157, in run_study
run_local_cas(my_study, options)
File "C:\opentelemac-mascaret\v8p2\scripts\python3\execution\run_cas.py", line 65, in run_local_cas
my_study.run(options)
File "C:\opentelemac-mascaret\v8p2\scripts\python3\execution\study.py", line 612, in run
self.run_local()
File "C:\opentelemac-mascaret\v8p2\scripts\python3\execution\study.py", line 440, in run_local
run_code(self.run_cmd, self.sortie_file)
File "C:\opentelemac-mascaret\v8p2\scripts\python3\execution\run.py", line 182, in run_code
raise TelemacException('Fail to run\n'+exe)
utils.exceptions.TelemacException: Fail to run
C:\opentelemac-mascaret\mpich2\bin\mpiexec.exe -wdir C:\Users\adm-local\Desktop\T500\cas_travaux_SP.cas_2022-02-15-15h25min07s -n 16 C:\Users\adm-local\Desktop\T500\cas_travaux_SP.cas_2022-02-15-15h25min07s\out_telemac2d.exe

Hi,
Try 'FORME DE LA CONVECTION' = 1;5 (instead of 14;5).

Regards,
Lan Anh

Dear Lan,

Thanks for this 2nd suggestion.
The simulation ran until the end but unfortunately, I still have the same instabilities.

Regards

Hi,

You have some ugly faces in your mesh.
Some nodes have more than 24 neighbors, it's recommended to have less than 9 neighbors.




You also have very small element (0.3 m) and a fixed timestep. Have you tried with a variable time step ?

You use option 1 for liquid boundary, try with 2 (Thompson method) for the faulty boundary near your breach.

Many thanks for this detailed review.
I will follow your suggestions and let you know the results.
Thanks again.
Regards

@nicogodet Thanks a lot, your suggestions appeared to be fruitful.
Here is the way I finally managed to stabilize the model:
- Remeshing with more appropriate density zones to suppress ugly elements
- Use of Thompson method for liquid boundary 1
- Fixed time step - s. I tried with variable time step but strangely, the model wet more unstable with huges flows going out from the model.

Subject closed, thanks again.

Nice !

BTW, I suggest to extend you model neear your breach to avoid influence of the boundary condition on the flow near in breach area.
With a BC so close to your breach, I'm not sure that the computed flow in your breach is correct.