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Old 11-18-2020, 12:03 PM   #881 (permalink)
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contrast

Quote:
Originally Posted by Cd View Post
After a fresh rain, I can clearly see the large vortex behind the cab on semis that are driving without their trailer.
I tried to get a video, but the contrast does not show up well.
Surely you all have seen this as well ( and the previously mentioned vortexes coming from wheelwells )
Once, I even was able to see a plastic bag that was caught in this vortex. It looks like a small tornado just behind the cab of the semi.
The airflow starts at the chassis just in front of the rear wheels and spirals upwards to the roof of the vehicle.
We have a section of divided, 4-lane, backed by a long row of evergreen trees. From the proper vantage point, this dark background really makes the water mist 'pop'.

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Old 11-18-2020, 08:09 PM   #882 (permalink)
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Some CFD action, the pretty colors can be artful at times.

PDF Download Paper.
Aerodynamic performances of rounded fastback
https://www.google.com/url?sa=i&url=...AAAAAdAAAAABAO
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1977 Porsche 911s Targa
1998 Chevy S-10 Pick-Up truck
1989 Scat II HP Hovercraft

Chin Spoiler:
http://forums.pelicanparts.com/off-t...effective.html

Rear Spoiler Pick Up Truck
http://forums.pelicanparts.com/off-t...xperiment.html

Roof Wing
http://ecomodder.com/forum/showthrea...1-a-19525.html
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Old 11-19-2020, 11:42 AM   #883 (permalink)
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More CFD action..................

Figure 42- uploaded by Pete Bachant
https://www.researchgate.net/figure/...ig37_315865543

Quote:
Contours of velocity magnitude generated using the steady, k-ω SST turbulence model for moving ground cases.

Convertible Aerodynamics
http://sersol.weebly.com/workshop/ca...e-aerodynamics



The COANDA Flow Control and Newtonian Concept Approach to Achieve Drag Reduction of Passenger Vehicle
Jung-Do Kee, Moo-Sang Kim and Byung-Cheon Lee
https://www.jstor.org/stable/44730994?seq=1
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George
Architect, Artist and Designer of Objects

1977 Porsche 911s Targa
1998 Chevy S-10 Pick-Up truck
1989 Scat II HP Hovercraft

Chin Spoiler:
http://forums.pelicanparts.com/off-t...effective.html

Rear Spoiler Pick Up Truck
http://forums.pelicanparts.com/off-t...xperiment.html

Roof Wing
http://ecomodder.com/forum/showthrea...1-a-19525.html
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Old 11-20-2020, 05:44 PM   #884 (permalink)
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I've been a fan of Coanda since I read about his 'afterburner' airplane.

Click for video

That third CFD appears to have a trunk-mounted spoiler. This windshield header device seems to be a diverging duct which would retard [if I can use that word] the air that wants to wrap around the header. youtu.be/ZDpScek3KBc?t=92 Here's it shown without the rear baffle plate.
That is surprisingly narrow, no wider than the headrests.
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Old 11-24-2020, 12:51 AM   #885 (permalink)
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I've been saying that the most promising tool for CFD is Blender. Here is a nine second example that uses the Starship:



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