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Hello,

I'm a new user of Telemac, BlueKenue and Fudaa.
I'm trying to understand the programs with the tutorial of the Baxter River.

I have realized all the operations in BlueKenue with success.
I think the problem concerns the BC.

In the tutorial, it is explained that the BC is a wall everywhere excepted at the east where we have to put "Open boundary with prescribed Q". Nothing is precised about the tracer code...

My first two questions are :
- with "Open boundary with prescribed Q", don't we have to impose a value for Q?
- what is the tracer code and what do we have to choose in this case?

I think I would impose a Q which is variable with the time but I don't know how...

I think also that we have to impose such open boundaries with prescribed Q at the west limit of the model but it isn't explained in the tutorial.

After this step, I export the file .bc2 and .cli.

In Fudaa, I have the following error messages :
-"WARNING : The tracer is defined as solid for a liquid border. It will be considered free".
- "INFO : Unsupported Cartesian Mesh".
- "Fatal error : The definition of borders nodes or boundary conditions is false. The borders can not be defined. It seems that the limits specified conditions are bad. It is advised to recreate a project from the geometry file"

This messages confirm that there is a problem with the definition of BC in BlueKenue but I don't know what.

Can you help me?

Thank you,
Olivier Bouhon.

PS : Sorry for my basic english.

Hello,

basically based on the expected flow regime (subcritical / supercritical) you have to define your open liquid boundaries: prescribed discharge, prescribed water depth / water surface elevation or a combination of both.
In the boundary condition file you specify which type of boundary you use. The values for Q and H are given in the steering file. If you don't deal with tracer transport, then the boundary code for tracer doesn't matter.
For imposing a time varying Q or H at a boundary you need to set up a liquid boundary file. You can do that in Fudaa but also manually. The whole topic about boundary assigment and creation of (unsteady) liquid boundary files is well explained in the Telemac manual and maybe also in some forum posts.

Regarding the error messages: maybe there is a mismatch between node numbering in Fudaa and BlueKenue what about I actually wonder. However based on the mesh file you can try to create the boundary condition file also in Fudaa which is straightforward like in BlueKenue.

Best regards,
Clemens

Hello Clemens,

thank you for your answer. I think I have to read the Telemac manual to understand this point.
My problem is that I don't know how I have to assign value of Q at my boundaries. It has to be the problem.

Thank you,
Best regards,
Olivier.

Hi Oliver,

I don't have same problem as you are facing, but I think if you just want to know how to put Q value for your boundary conditions, so I think after heading BOUNDRAY CONDITIONS in your steering file, you have to use a key: STAGE-DISCHARGE CURVES (please read reference manual p.62-release 6.2, and use manual p.19 &34- Release 7.0).

Then, after heading INPUT-OUTPUT, FILES, you have to use a keyword: STAGE-DISCHARGE CURVES FILE = ....txt (you have to create this *.txt)

General, what you want to know is clearly described in TELEMAC_2D_Baxter_tutorial_files (I thought you have also read it)

I am also a new TELEMAC user, hope this helps.

Regards

Huy

Hello,

to clear up some things:
Telemac reads the keywords from the steering file in a sequential way and there is no dependency on "headings" (the headings are only comments).

You don't need a stage-discharge curve for prescribing boundary conditions.

Merely as an exmaple: you want a discharge of 10 m³/s at the inlet (boundary number 2) and a water surface elevation of 5.0 (boundary number 1):
PRESCRIBED FLOWRATES = 0.0;10.0
PRESCRIBED ELEVATIONS = 5.0;0.0

Of course first you have to create the boundary condition file by assigning the appropriate conditions, like Q and H, for the inlet and the outlet.

Best regards,
Clemens

Thanks Clemens,

And of course, you are absolutely right. Headings are just comments. My thought also is: if discharge rate is constant, there is not necessary to have a stage-discharge curve.

By the way, could you please clarify the meaning of 'Tracer' in CONLIM Boundary Segment Editor in BlueKenue? is it about temperature, pressure factors at the boundary?

Best Regards

Huy

Hello Huy,

with Telemac you have the possibility to simulate the transport of tracers which can be e.g. salinity or temperature. Have a look in the Telemac-2D User manual v7.0, page 70. See also this wikipedia article:
en.wikipedia.org/wiki/Flow_tracer or in one of your books in your profile picture .Pressure is really something different.

So unless you don't have to deal with tracers in the conlim file you can ignore the column for the tracer setting.

Best regards,
Clemens

Yeah... I got it,

Thank you so much again

HUY