Hi Tony, Flow works on the "underlying surface". Your windshield edge is trimmed out of a large surface, you can see the full surface by selecting it and using Edit > Show pts, which looks like this:





So using that as a flow target is going to generate a result across that base surface, not one that follows the windshield edge.

Instead you'll need to construct a surface using something like Loft or Sweep that will make a surface like this (here using Loft after joining the 2 half pieces):





- Michael