open TELEMAC-MASCARET The mathematically superior suite of solvers

Hello,

We try to run a TELEMAC2D model using a discharge-rate file (keyword FICHIER DES COURBES DE TARAGE) at the downstream liquid boundary (liquid boundary 1).
We want a Z(Q) relationship, so here are the values of the keywords that we impose :


/

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/ ENTREES-SORTIES, FICHIERS
/

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FICHIER DES PARAMETRES ='Qh_v1.cas'

FICHIER DES COURBES DE TARAGE ='Tarage_RD139.ctr'

FICHIER DES RESULTATS ='Qh_v1.res'

FICHIER DES CONDITIONS AUX LIMITES ='Qh_v1.cli'

FICHIER DE GEOMETRIE ='Qh_v1.geo'

FICHIER DES FRONTIERES LIQUIDES ='Q100_4Db_cal_Qh.liq'

/

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/ CONDITIONS LIMITES
/

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COURBES DE TARAGE =1;0;0;0;0;0;0;0

/

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/ EQUATIONS, CONDITIONS LIMITES
/

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PROFILS DE VITESSE =1;1;1;1;1;1;1;1

OPTION POUR LES FRONTIERES LIQUIDES =1;1;1;1;1;1;1;1

DEBITS IMPOSES =0;10;10;10;10;10;10;10

COTES IMPOSEES =50;0;0;0;0;0;0;0

However, when we launch the simulation in parallel mode (8 threads), the discharge-rate file seems to be read but the rating curve is not taken into account in the simulation.
We’ve tried to change the type of the liquid boundary (imposed flow, imposed elevation…) but it does not seem to work better: the simulation is running but the elevation at the downstream boundary does not correspond to the flow.

Is there something we have forgotten?
Would there be a problem using the parallel mode?

Thank you for your help.

Hi,

I can not detect any wrong keyword in the list you have introduced. However, the problem could be in your stage-discharge file. Be sure that your initial elevation corresponds to what indicated in the stage-discharge curve; otherwise, large variation will be imposed and Telemac will not have enough time to reach prescribed elevation.
Moreover, you can copy routine sta_dis_cur.f in your fortran file and see how well it works. Remark that (at the end of this routine), a relaxation coefficient is used (0.02) that could be lowered to smooth sudden variations.

I hope that this will be helpful.

My best regards

Riadh

Hi

Was an solution found for this problem? I have the same issue with the rating curve in Telemac-2D v6p2. Rating curve is read (table written at the beginning of the listing file) but the curve is not taken into account in the calculations. In v6p0, I used to have a notification at each time step like this one:

FRONTIERE LIQUIDE : Q(1) = 32.0000000000000

Thanks,
S.

Forget what I said about the notification at each time step (it was from an incoming hydrograph).
S.

Hello,

Can you send me your case and I will try to check what is wrong with it.

Riadh

Hi Riadh,

Here is the case I'm working on right now. The simulation domain is large and includes a river and a canal. For simplicity, I only test now the rating curve for the river reach. I tried before the rating curve in the canal but got the same kind of results. In the test case I send you, the river flow is 2000 cms. Then, the downstream water level should be 25.0 m according to the rating curve. Unfortunately, that's not what I get as result : water level at downstream boundary is about 22.0 m.

I got good results of rating curve for another simpler model...

Thanks for your help,
Simon

Hello Simon

There are two main problems
1- for rating curve, you need to use 5 4 4 condition in your boundary file. You are using 4 4 4 condition which is equivalent to a free output.
2- to activate the rating curve, you need to begin with a "hot start" i.e. you need to generate a steady state with a prescribed elevation downstream and after restart using the rating curve condition.
I remarked also that the botton is constant all over the main channel, is it a realistic bathymetry ?

I hope that it is helpful.

With my best reagards.

Riadh Ata

Hi Riadh,
I followed your advices and it worked. Your're right about the flat bottom bathymetry: it's not real. I'm waiting for the real one.
Thanks,
S.