I wanted to create a Custom Field Function which would show me the distribution of a normal component of the velocity to some surface (not a wall) and I failed. Does anybody have any experience of doing that? Thank you, Alexandre.

I think it is not possible to create an custom field function to do this work. I guess it is better to write a user defined funtion which calculates the normal velocity. U can save the velocity distribution in a user defined memory an then display it.

Thank you, Michele. It is possible! I used Grid -> X,Y,Z surface area projections to define a normal component of the surface ... and then it was easy. Thank you again. Alexandre.