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Hi!

I simulate a water flow through a valley in telemac2d(v8p3r0). I set two open boundaries,one for the inflow boundary(4 5 5) and the other for the outflow boundary(4 4 4). When the water reaches the outflow boundary, the water does not flow out.I wonder what went wrong.

I attanched all the documents.

Please help me.

Many thanks.

ryuuame

Hello,

You should better use boundary conditions for well posed problem, like prescribed flowrates at the entrance and prescribed elevation (possibly with a stage-discharge curve) at the exit if the flow is sub-critical or prescribed flowrates and elevation at the entrance and free exit if the flow is super-critical, rather than prescribed flowrates at the entrance and free exit with Thompson conditions. Your output liquid boundary condition is quite large (see the whole green line) and the Thompson conditions are applied along the whole liquid boundary. That may be an issue visualising only at one part of this liquid boundary.

Hope this helps,

Chi-Tuan

Thank you Chi-Tuan!

If I want to simulate 2 boundaries, one for the water flows in(boundary number 2) and the other for the water flows out when the flow reaches the boundary(boundary number 1) , can I define the keywords in steering file like as follews ?

/the outflow boundary's bathymetry is 100m
LIQUID BOUNDARIES FILE = inflows.liq
PRESCRIBED ELEVATIONS = 100 ; 0.0
OPTION FOR LIQUID BOUNDARIES = 1 ; 1

Also, I wonder if the flowrates can be set at the initial zero moment of the discharge curve, like 6000m3/s ? I tried to set a big discharge at the start, and all the flux of boundaries went wrong. Can you tell me how to fix it ?

Regards

Hello again,

I strongly recommend you to read the TELEMAC-2D user manual available here:
wiki.opentelemac.org/doku.php?id=documentation_v8p4r0
in particular section 4.2 dedicated to prescribing boundary conditions.
You can also find the hint "ramp" for your last question.

Hope this helps,

Chi-Tuan

Hello again,

I have carefully read the setting of boundary conditions in 4.2. It is already possible to simulate the outflow boundary. But my second question remains.

When I set the flow process line for the inflow boundary condition, if the flow rate is slowly increasing, the calculation is feasible.

If the change starts from large to small at zero moment, the flux and volume of the entire domain went wrong.
inflow boundary(4 5 5) outflow boundary(5 4 4)

I put the files in the attachment. Please help me to solve the problem.

Regards.

ryuuamne