open TELEMAC-MASCARET The mathematically superior suite of solvers

Good morning,

I try to simulate runoff on a catchment.

After a first computation, the results were quite strange : there was no water in the catchment despite increasing volumes of rain fallen.

I sought on the forum and found some advices :
+ Saint-Venant VF
+ VF scheme : 5
+ Courant number : 0.8
...

I tried again but then got an error "bancs découvrants" (tidal flats ?) has to be true. In fact, it is already true.

Has someone an idea, how this can work please ?

Attached :
+ BV32_PluieReelle.cas : first try
+ BV32_PluieReelle_VF.cas : finite voulumes method
+ BV32_..._frotran : fortran file for rain
+ CL_BV32.cli : boudary conditions
+ Hyeto... : rain (I tried to put huge volumes to be sure the problem was not there)
+ Pb.noWater : screenshot "first" try
+ Erreur_bancsDecouvrants : screeshot "second" try

Hi
It should works with the FE equations...
As the geometry file is missing, we can't test your case.
I think the problem is potentially located in the name of private variable as it should be a string of 32 characters (16 for name and 16 for unit)
Just to check, try to run the rain example case and if it works try by adapting elements one by one
Regards

here is the geometry file

www.grosfichiers.com/eVnajRJfcdv

c.coulet wrote:
I am certainly not gifted but, even though I know there is a library somewhere, I did not manage to find it ?

This project was created by a former intern (who is not available now and so for a few months).

You wrote this project was created by someone else, but did this project already gives computational results?
Did you change something in this project?


The rainfall exemple is in <opentelemac-directory>\examples\telemac2d\pluie

Hello!

There are a couple of things that are unclear / wrong in your cas files. For example, with FV, you need to set a variable time-step.

Anyway, some tips to get you going:
- As Christophe mentioned, define the name of your private variable as 'CN ' with total 32 characters. Do you have confirmation that the value is correctly read in the sortie file? It should be mentionned some lines before the start of the time loop. That would be the most logical explanation: variable not found, PRIVE(1) initialized to zero and therefore no runoff is produced (CN = 0). You can also output it to your result file to check (variable N).
- As I understand you are using version 7.2. If I remember right, there is a small mistake in the code when using FV, in prosou.f (or prosou_fv.f), there is a test on BANDEC that leads to a STOP is BANDEC is false. The problem is that when using FV, BANDEC is automatically set to false even if you set it you true in the cas file. Simply remove the test and STOP. Then I am not 100% sure but I think that some modifications was further required in majzz.f to get rain fully working with FV in 7.2. I would strongly advise to go over to 7.3 or even better 8.2 as all those small bugs have been corrected.

Good luck!

Kind regards
PL

Hello all,

If you want to use Finite Volumes schemes, you are stronly advised to use the latest release (v8p2) as they were rebuilt last year with many bugs which were solved and more features are available.

Hope this helps,

Chi-Tuan

Good evening,

Thanks both of you for your answers.

I did several tests this week-end to be sure and apparently I get consistent results for different rains and different catchments.


In the EF version, it appeared that the main problem was effectively a wrong definition of the CN in the geometry file. However it seems that writing "CN" alone in the .cas without quotation marks nor 32 characters does not bother the calculation (in cmd, I get a line "Variable CN trouvée dans le fichier de geometrie").

I also found out that apparently a to long file name can be a source of error (reducing one permitted the solution of an error and beginning of calculation).


I did not try the VF version with the modifications of the source codes (mostly feared for telemac not working anymore at all after intervention).

For the upgrade, I'm quite reluctant : while setting up Telemac, solving compatibility issues with other softwares (mostly because of Python) conducted to a relative stability of the whole thing which I fear to lose.

Thank you again for the quickness and the accuracy of your answers, it's really valuable !

Hello,

Thanks for the update, happy to see it is now working.

Yes, avoid lines with more than 73 characters in the cas file, this is a common source of errors as by default fortran is limited to this length.

If you plan to use TELEMAC for runoff modelling regularly I would advise you to update to a newer version. You can always install a new version and keep and use old ones. If your python environment is set up, you could easily install say 7.3 as ony the systel file needs to be updated. For the latest versions (from 8.1 I think?), Python 3 is however required.

Kind regards
PL