open TELEMAC-MASCARET The mathematically superior suite of solvers

Hi everyone

I hope you can help me in the following problem:

I am modeling a channel as shown in the file "geometry". In the file Borde.cli I place a condition 5 6 6 in the inlet and in the file telemac.cas I put:

/ EQUATIONS, BOUNDARY CONDITIONS
PRESCRIBED VELOCITIES = 0.0; 0.5264
OPTION FOR LIQUID BOUNDARIES = 1; 1
PRESCRIBED ELEVATIONS = 9.8158; 10.0158
VELOCITY PROFILES = 1; 1

First I run on TeleMac 2D module to get a "PREVIOUS COMPUTATION FILE".
Then, I run the same model with the Sisyphe module but I put in the file sisyphe.cas the reading of the file BordeS.cli, since, I want to get the balance I put in LIEBOR = 5 and EBOR = 0. (The file Borde.cli and the file BordeS.cli is the same exept for this condition in the inlet)

Then when delivering the result, I find something very strange in the inlet, there is a little erocion and in some nodes there is a large deposit (much, passes the SL from 10 to 200).

What could this be? It seems strange to me at the moment of placing LIEBOR = 5 and EBOR = 0 should not modify the bottom in the inlet, in addition with the condition elevations elevations also I should not change the free surface.

Thanks!

Hi Joaquín,

Could please try using into the boundary conditions file, at the inlet

4 5 5 0.000 0.000 0.000 0.000 5 0.000 0.000 0.000 1 1

I hope it helps!

Cheers,

José

Hi Jose


Now that I see that, it should not be:
5 4 4 0.000 0.000 0.000 0.000 5 0.000 0.000 0.000 1 1 ??

Thanks

You are prescribing a water level and velocity at the inlet boundary. If the water depth varies, that will mean that in some nodes the water level will accelerate, causing erosion, while in other nodes the water will decelerate, causing sedimentation.

In general, it is better to use a discharge at the inlet boundary (4 5 5 ...), letting TELEMAC decide how to distribute it over the boundary, and a water level at the downstream boundary.

Hi everyone

I have taken into account your considerations, again when running the files varies the depth and this way varying the discharge in inlet that I want to leave constant.

Any other ideas because I have this problem?

Thanks

Your problem seems to be ill-posed.
Which are the flow conditions? Subcritical or supercritical flows? This will determine the type of BC to be imposed.

pablo

Hi pablo

The conditions in inlet and outlet are supercritical flow, that is why in the cli file of telemac use in the inlet
5 6 6 0.000 0.000 0.000 0.000 4 0.000 0.000 0.000
and outlet
5 4 4 0.000 0.000 0.000 0.000 4 0.000 0.000 0.000.
Instead the cli file that reads sisyphe use the recommendations I was given:
4 5 5 0.000 0.000 0.000 0.000 5 0.000 0.000 0.000 in inlet
and 5 4 4 0.000 0.000 0.000 0.000 4 0.000 0.000 0.000 outlet,
as I still had the same problem Change the condition in inlet by
5 5 4 0.000 0.000 0.000 0.000 5 0.000 0.000 0.000 (which is the one I think is correct) and also I still have the same problem that deposits me a lot of sediment in some nodes and consequently changes the discharge In inlet.

Thanks

Hello Joaquín,

As Pablo said, it seems to be ill-posed.
Could you please try prescribing discharge and elevation at inlet?
Thus, TELEMAC could compute the velocities.

In addition, at outlet you do not need to prescribe anything, with 4 4 4 (free flow condition) would be enough.

Also, as I said in my previous post, in Sisyphe to set no evolution at inlet
4 5 5 0.000 0.000 0.000 0.000 5 0.000 0.000 0.000 1 1
This should work (this has worked for me).

I hope it helps.

Cheers,

José

Hi Jose

I try to describe the speed and height at the entrance, since, I have a supercritical flow. That's why I put in the cli file that reads Telemac 5 6 6, but the cli file that reads the Sisyphe I do not know what values ​​to put, (I think it can be 5 5 4), use your recommendations from 4 5 5 and get the same problem. Put 5 5 4 and also get the same problem.

Iwant to get a constant discharge which is what I'm not getting .

Thanks for the help.

Finally, it may be that the problem comes from using the full width of the channel as input stream ??


Thanks for the help

Joaquin