open TELEMAC-MASCARET The mathematically superior suite of solvers

Dear all,
I'm using Telemac2D, version v7p0. I defined a weir in my mesh. There are a open border where I use the condition as H defined in my network and other 5 border as Q defined. The simulation works seem correct when I defined H in my QH.qls file. Unfortunately, when I use option with astronomy tide thanks to define in my steering file instead to defined H in QH.qls, the simulation failed when the water level rise to crest of weir.
There are the instruction in steering file when I use astronomy tide condition on open border as:
/

---

SYSTEME GEOGRAPHIQUE : 2
NUMERO DE FUSEAU OU PROJECTION DANS LE SYSTEME GEOGRAPHIQUE : 48
OPTION POUR LES CONDITIONS AUX LIMITES DE MAREE : 1
BASE DE DONNEES DE MAREE : 2
COEFFICIENT DE CALAGE DU MARNAGE : 1.11
COEFFICIENT DE CALAGE DU NIVEAU DE MER : 0.0
INTERPOLATION DE COMPOSANTES MINEURES = OUI
/

---

I don't know why. The simulation works correct when I remove the weir in my mesh and still use the astronomy tide on the open border. Would you like give me some suggestion? Thank you very much in advance.
Best regards
Thong NGUYEN
HCMUT, VN

Hi Thong,

Difficult to answer without all the files.
Perhaps your level is too low when you impose the tide?
Did you have an output message before the end of your simulation?

Regards,
Olivier

Hello Olivier ,
Thank you very much for your prompt response. I have verified that the initial level of Z for two cases are the same (0m), (case with Z initial =0m and Z change in time imposed par QH.qsl file, this simulation works seem correct and the second case where I'm using the astronomy tide thanks to define in steering file, the simulation failed !). In the second case, the simulation runs but with some value information on screen being NAN when the water level of point (side 1 or side 2 of weir) rise to crest of weir!
The elevation of my mesh are between -20m to +5m. I'm preparing a model 2D to calculate the whole delta of Mekong in VN where there are the roads that I would like to simulate as the weirs.
Best regards
Thong NGUYEN
HCMUT, VN

Hi

I suspect that you have no water downstream the weir.
When the level reach the crest of the weir, there is a computation of discharge which should normaly be applied as a negative value on the upstream side boundary and as a positive discharge on the downstream side.
As it's managed as a boundary condition (you could have a look into bord.f and clsing.f) if you try to impose a discharge on a wet boundary you probably met the same situation as when you impose a discharge on a normal boundary without water...

Hope this helps

Hello Coulet,
The initial water level was setup at 0.6m. I have checked which this level water, the height of water of these points are positives. Morever, why does the simulation works seem correct when I remove the option with astronomy tide in my steering file? (the other element of simulation are the same) I defined always the water level in QH.qsl file in two cases (shape similar with astronomy tide that I have from the result of other simulation in the same period). In the case where I use the option with astronomy tide, I think that the water level defined in QH.qsl file will be ignore, that's right? Thank you for your help.
Best regards
Thong NGUYEN
HCMUT, VN

Hello Mr. C. Coulet,
It seem that the variable UBOR%R(K) and VBOR%R(K) are not correctly calculated in the SUBROUTINE TIDAL_MODEL_T2D. I think that the UBOR(I1) and VBOR(I1) calculated in SUBROUTINE CLHUVT aren't updated in UBTIDE%R(K) and VBTIDE%R(K) in SUBROUTINE TIDAL_MODEL_T2D! That's why my simulation isn't failed when I only use the option with Z defined by QH.qsl file. What do you think about this remark? I have modified a litle in SUBROUTINE CLHUVT et SUBROUTINE BORD, the simulation isn't failed, that mean the simulation runs with the option of astronomy tidal was chosen. Thank you very much for your suggestion.
Best regards
Thong NGUYEN
HCMUT, VN

Hello,

I met a problem once when mixing tide conditions and weirs: the liquid boundary is initially only defined for the boundary with the tide conditions. The weir only becomes a liquid boundary during the computation and so the code might mix up the 2 boundaries. So you need to add a logical distinction between the nodes of the tidal boundary and those of the weir.

Hope that helps,
Chris.