Hey Michael, Thank you for taking the time to explain this, I get it now.
Much appreciated

Your line is 20
If i take a part of circle of 20
Flow the part Line to Part of Circle will give the result wished! ;)

In fact the Flow method can support some styles of results! :)
Depend of what result wanted with Line, Surface, Volume...
...and where are the different items
Line - Line : strict ... volume follows line
Line - Surface : can be degressive ... volume can enter inside the surface
Surface - Surface : Strict ...volume follows the surface