I'm not finding a "Continuum Dynamics tail"..but "... aerodynamic backward's-facing step" is plentiful. These only show the step(off) surface & the reattachment zone surface being parallel... except the step in a wing.
Following your graciously provided instructions "measure 'down', 'over', and 'up',"..etc. It appears that the length down stream the step could be longer than the reattachment zone..based on the Mair tail, just not shorter? Is there any concern regarding the 3-4" radius of Moby's corners..of the step?
The Ame's wind tunnel at Moffett Field is familiar. I called NASA (1998) requested a tour, "for my son's high school science project". We didn't get into the biggest, but had a great day touring a smaller one. One of those sure would be handy.
