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Love that they (Whomever "they" are) will release photos like this. Probably in part for propaganda, but cool nonetheless.
The smoke tells a story, even in stills. In the Prius photo, the light is sufficient for a high shutter speed. The Ford, probably a longer shutter because you don't see the details in the turbulent areas behind. (And the airfoil photo looks almost like an extend exposure because there is no indication of motion or turbulence -- which may be partly true just because of what we know if it's shape.) Going back to the Ford, the dispersion aft the cab is the real clue to turbulence there. Don't see that nearly as much in the Prius photo.
The big thing missing is the air speed in these photos. It may be that speed is higher for the Ford so it looks like a longer exposure just because the particles travel farther during the shot. The Prius may be at a much lower speed so turbulence is not as much a factor. Hard to tell, of course.
Finally, the discharge point with the Prius is much higher (compared to the hood) than the Ford. The closer to interaction with the boundary layer, the more turbulence is likely to appear.
What is interesting, at least to me, is the "wedge" below the smoke on the Prius from the hood, following up the windscreen and over the roof. Compare to the Ford, and the "wedge" disappears at the intersection of hood and windscreen. Part of that is a visual effect because of the introductory point, but part is geometry indicating greater pressure differentials through that area. I personally think they did a better job on early versions of the Prius, and this geometry change may be more for consumer acceptance (and easier cleaning of the windscreen on the inside -- and ice on the outside) than for aerodynamics.
Final thought -- why, if the goal is better fuel econ, do they not use full wheel covers? I'm continually baffled at why "they" would release photos like this apparently showing off the aerodynamics, yet neglect some of the easy fundamentals that could be integrated into a design (not just wheels) without really effecting the look. #OpportunitiesLost
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