open TELEMAC-MASCARET The mathematically superior suite of solvers

Hello everyone,

i'm analyzing a flood event along a river (2 km long) in Telemac 2D. My available Boundary Conditions are varying water elevations(outlet) and discharges(inlet), which i implemented using a liquid boundary file. However the water which flows out the river and not back to the river should leave the mesh some where else. I attached a figure for your understanding, the red line is the BC at the outlet (WaterLevel). The yellow line is where the water in case of a flood event exits in reality. At the moment the water just stays there which is not correct.

So my question is, if it is possible in Telemac to set there a BC which allows the water a free exit? In other words if there is water the water should flow out the mesh and if there is no water noting should change.


Best regards,
Markus

Hello,

You can put a boundary condition with all variables free (4 4 4) but this sometimes happens to be unstable. You can preferably apply a Thompson boundary condition on this boundary, which consists in also setting all variables free, but giving the keyword : OPTION FOR LIQUID BOUNDARIES= one value per liquid boundary separated by ; with 1 for normal boundaries and 2 for those with Thompson. Be aware that if this boundary has a fluvial exiting flow, one data may be missing: the knowledge of downstream boundary conditions and you will get one solution out of an infinity.

With best regards,

Jean-Michel Hervouet

Hello Jean-Michel Hervouet,

thanks a lot for your advice. I tested it and it seems that i works quite well.

Best regards
Markus