Hi Heiner, if you're having what looks like randomness in the result it's most likely the result of clicking in slightly different areas on each surface on each run-through. For example make sure not to click right exactly on a corner of the surface, because what is actually targeted is an edge and if you click right on a corner it's pretty ambiguous which particular surface edge actually gets targeted.

Can you please post the 3DM model file that is giving you the random-like flow behavior? I will take a look at it and then maybe be able to give you some more specific advice on where to click on it to control it better.

I have thought some about trying to rework the Flow command to be easier to understand. It's somewhat difficult because it can be used in a lot of different ways.

- Michael