Hey PL.
Thanks a lot for your help. I figured out the problem. It was simply that the nodes on the left tube were too close to the bank. Sorry, my bad, heheh.
I have maybe one last comment. The formulae for flow in tubes are not in telemac-2d_user_manual_en_v7p0.pdf
I had a look at buse.f and figured out the formula, but of course it would also be nice to have it as an equation in the manual.
Thanks again!
Roberto