open TELEMAC-MASCARET The mathematically superior suite of solvers

Hi,there!

According to the v8p1 manual,as for the friction parameter definition,"In the case of option 7, the key-word MANNING DEFAULT VALUE FOR COLEBROOK-WHITE LAW must be given.".When I did like this in the steering file，the following error occured(pleas see the attached picture).The error can be solved by adding the key word"FRICTION COEFFICIENT" with or without "MANNING DEFAULT VALUE FOR COLEBROOK-WHITE LAW".
So my question is the manning value is given by which keyword? FRICTION COEFFICIENT or
MANNING DEFAULT VALUE FOR COLEBROOK-WHITE LAW?
If I want to change the manning value, how should I do?

Looking forward to your reply.
Best wishes
Hong

Hello Hong,

Which release are you using? I think a release older than v8p1.
Indeed, since release v8p1, an unexpected choice should not be allowed by Python scripts and they should stop the computation before entering the FORTRAN part: you should not have gotten this error message with a v8p1. The allowed choices are written in the telemac2d.dico file (T2D dictionary).

If using an older release than v8p1, I think that even if you fill in FRICTION COEFFICIENT keyword with LAW OF BOTTOM FRICTION = 7, your computation should stop with an error message like : "COEFRO: UNKNOWN LAW OF BOTTOM FRICTION: 7", can you confirm?

Anyway, the TELEMAC-2D user manual is tricky as it can be thought laws of bottom 6 and 7 are available, it will be change for next release (v8p2). However, they are available for lateral boundaries.

Hope this hellps,

Chi-Tuan

Hi，pham

Thanks for your reply.

The release I am using is v8p1.I just intalled it several days ago.

So I'm still confused.

Would you please tell me what should I do if I want to change the manning value?

Best wishes

Hong

Hello Hong again,

Very strange that Python scripts do not stop you immediately.
I have just tried the goutted example with a v8p1 release and I get:

Traceback (most recent call last):
File "/data/rd/projets/projets.002/systel.002/old_release/v8p1r1/scripts/python3/telemac2d.py", line 7, in <module>
main('telemac2d')
File "/mnt/.tgvdv2/projets/projets.002/systel.002/old_release/v8p1r1/scripts/python3/runcode.py", line 272, in main
run_study(cas_file, code_name, options)
File "/mnt/.tgvdv2/projets/projets.002/systel.002/old_release/v8p1r1/scripts/python3/execution/run_cas.py", line 154, in run_study
my_study = Study(steering_file, code_name, options.w_dir)
File "/mnt/.tgvdv2/projets/projets.002/systel.002/old_release/v8p1r1/scripts/python3/execution/study.py", line 93, in __init__
self.cas = TelemacCas(self.steering_file, self.dico_file)
File "/mnt/.tgvdv2/projets/projets.002/systel.002/old_release/v8p1r1/scripts/python3/execution/telemac_cas.py", line 70, in __init__
self._check_choix()
File "/mnt/.tgvdv2/projets/projets.002/systel.002/old_release/v8p1r1/scripts/python3/execution/telemac_cas.py", line 213, in _check_choix
.format(key, value, list_choix))
utils.exceptions.TelemacException: In t2d_gouttedo_Colebrook.cas:
The value for LAW OF BOTTOM FRICTION (7)is not among the choices:
{'4': 'MANNING', '0': 'NO FRICTION', '3': 'STRICKLER', '1': 'HAALAND', '5': 'NIKURADSE', '2': 'CHEZY'}

As expected.

Just to understand, have you done a classical installation or a tuned one with some non standard parts?
Can you please share your steering file + enclose the whole output file from your running command to the error message you got: "THE LAW OF BOTTOM FRICTION 7 IS ASKED GIVE THE CORRESPONDING FRICTION COEFICIENT" (I can see a mistake in COEFFICIENT, to be changed).

Maybe you should use another law of bottom friction as it does not seem to be expected.

Thanks,

Chi-Tuan

Hello Hong,

the Colebrook-White law is only for lateral friction. If you try to use it for the bottom there will be an error message. So I guess that you used:
LAW OF FRICTION ON LATERAL BOUNDARIES = 7.
Your error message probably come from the case that you don't give the roughness coefficient for the bottom (FRICTION COEFFICIENT).

Concerning your question: The Manning default can be given by the keyword: MANNING DEFAULT VALUE FOR COLEBROOK-WHITE LAW. If it is not set in the steering file, the value from the dictionary (=0.02) will be used.

Best regards,
Rebekka

Thanks,kopmann.

I got it.

Maybe the "default"in the keyword"MANNING DEFAULT VALUE FOR COLEBROOK-WHITE LAW" be omitted is more acceptable. Right? :)

Best wishes
Hong

Hello,pham!

Sorry for the late reply.

I have uploaded the files you need.Please see the attachments.

The weird thing is although the friction coefficient is required, the roughness is still changed through the keyword"MANNING DEFAULT VALUE FOR COLEBROOK-WHITE LAW".

Best wishes

Hong

Hello Hong,

I think I have understood why you can use LAW OF BOTTOM FRICTION = 7 (Colebrook-White law): can you confirm that you use Python 2 rather than Python 3? If yes, you are strongly advised to use Python 3 as every new feature and fix was only done for Python 3 for release v8p1. Python 2 were scripts not updated as not recommended for this release.

As Rebekka answered, Colebrook-White law is only for lateral boundaries, not bottom boundary. This choice should have been forbidden before even using Python 2 scripts in the FORTRAN sources.

Anyway, reading the source files, what is done with your choices is:
If you give a FRICTION COEFFICIENT, the CHESTR array is filled by this value in FONSTR subroutine. Then, this array is used in FRICTION_CALC with CASE(7): If you gave the value 0.02 in the steering file, as the water depth seems to be generally greater than 0.02 m, the keyword MANNING DEFAULT VALUE FOR COLEBROOK-WHITE LAW is then used for every node with water depth > 0.02 m. That should explain what you experienced with your choices.

To conclude, I think you have faced error messages + strange behaviours because you have used a law for bottom friction which should not be used. My advice is to use another law for bottom friction, available in the list of choices in the TELEMAC-2D dictionary (from 0 to 5).

Hope this helps,

Chi-Tuan

Thanks for your advice, pham.

I have used another law for bottom friction.

The version of python I am using is Python 27,so should I just install Python 3 through the installing file?

Best wishes
Hong

Hello Hong,

As told on Python website (www.python.org/doc/sunset-python-2/), Python 2 has not been supported since January 2020. It is time to upgrade to Python 3.
For the TELEMAC-MASCARET, we had not waited for this time and have been developing Python3 scripts with many new features (postel, pretel...), fixes and so on for months/years. Python 2.7 scripts have not evolved since many months...

FYI, there will be no Python 2.7 scripts available for release 8.2 and next ones.

It is time to move on to Python3, the dedicated scripts are already available, you just need to install Python 3 (and reinstall TELEMAC-MASCARET from the Python 3 scripts).

Best regards,

Chi-Tuan