Hello,
Yes it is true, this velocity is assumed to be 0, but you have a little chance, it is hardcoded in POINT_TELEMAC3D as W_SCE%R, so you can try to take this subroutine in your Fortran file and try another value. I can add it as a keyword in the next release. However depending on what is your source, the results may not be what you expect. For example if the source is a pipe there may be a strong difference between upstream and downstream the pipe, whereas with a point sources the source will equally influence downstream and upstream, which may triggers patterns of recirculations that do not correspond with your device.
With best regards,
Jean-Michel Hervouet