You should be able to get to the tab in the Appearance Editor for "Advanced", which then gives you the opportunity to change the transparency.
You would have the right answer but I guess this question should not be ask here since you got to have floefd to answer it. There is a specific way to answer it in floefd.
It's compressive flow analysis software. I think FloEFD is a Mentor Graphics tool. Another product called CFDesign has been purchased by AutoDesk. It has similar features in that it can calculate and perform compressive flow analysis (liquids, gases, etc).