Downwash is not attached flow. It is symptomatic of flow separation. You'll get the highest drag, vortex-drag, plus a small, but very low pressure wake, and overall higher drag. To say otherwise is delusional. It may look like a duck, but it doesn't quack like a duck.
"Attached flow caused by vortices is still attached flow." I can't believe this is even contested or debated, the only place I have ever seen it said that it isn't is in aerohead posts.
Out of curiosity I searched ecomodder for attached flow and found a quote, basically the same debate
Quote:
Originally Posted by aerohead
Disagreement is healthy and I always learn.
Later saying...
With respect to the 30-degree fastback,flow will be attached along the centerline only,with attached longitudinal vortices on both sides.
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So it seems in 2011, on a fastback the flow will be attached along the centreline, but also with attached vortices on both sides. Sounds pretty attached to me.
The same thread also discusses this chapter,
https://books.google.co.uk/books?id=XEGZIZ5zhy4C&lpg=PP1&pg=PA115&redir_esc=y #v=onepage&q&f=false
aerohead said in that thread: "Once the tangent angle on the roofline exceeds 22-degrees(as measured against the horizon)the flow cannot remain attached." This picture (and many many others) says different
(page 128)