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hi,
In the page 30 of TELEMAC2D manual, there is one sentence "because the finite element interpolation will generate a non-zero flow though a solid
segment. In this case, it is better to cancel the velocities on the first and last points of the boundary". However, how to realize the "cancel"? modify the boundary file?
Thanks.
Jinyong Zhao

Hello,

You can give a profile of velocities in the BOUNDARY CONDITIONS FILE (look at the keyword VELOCITY PROFILES). Then if you give a flowrate through a liquid boundary, the final prescribed velocities will be proportional to this profile.

Example, assume you want to do this on your boundary number 2, with a flowrate of 50 m3/s, you would have:

VELOCITY PROFILES : 1;2 (the second one means option 2 for boundary 2)
PRESCRIBED FLOWRATES : 0.;50.

in the steering file, and in the corresponding lines for boundary 2 in the boundary conditions file :


4 5 5 0. 0. 0.
4 5 5 0. 1. 0.
4 5 5 0. 1. 0.
4 5 5 0. 0. 0.

these lines represent a boundary with 4 points, and only the 2 points in the middle will have a non zero value (the 1. will be multiplied by a constant to give the correct discharge).

Usually in this boundary conditions file you find only 0. for velocities because with option VELOCITY PROFILES : 1;1 we discard the values and take for the velocity a vector normal to the boundary.

Please also look at a simple case in a simple canal, where you do not need to do this, this is just for a lateral inflow in a wall.

I hope this helps,

Jean-Michel Hervouet