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Old 01-07-2010, 01:25 AM   #1 (permalink)
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Snow mods: We have been bested by mother nature.

It seems that high winds and snow, in the hands of mother nature crafts aerodynamic shrouds that put us to shame:

Snow Mods: Ten Cars Aerodynamically-Enhanced By Mother Nature - Snowpocalypse - Jalopnik

The snow was accumilated and erroded and the most aerodynamic shape found naturally. The result is impressive in the pictures, when I first saw it I thought it had been carved by cheeky ecomodders. So did anyone in that area get out and make a mould or template from those shapes?

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Old 01-07-2010, 11:03 AM   #2 (permalink)
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Seeing those fantastic shapes makes me wonder...

Wouldn't it be interesting to have access to a computer program that would
simulate how wind driven snow builds up on a 3D object. This goes beyond
mere flow line visualization. And it goes beyond showing velocity and
pressure distributions in 3D.

For sure it would take a lot of computational power. And there would be the
matter of specifying how the snow would accumulate, "stick" together in
moving air.

I have come across references to snow drift prediction software used in
archetecture and mechanical science applications. So, maybe the capability
already exists in the halls of academe.

But I would think that a large part of snow drifts is the flakes sort of
"falling out of solution" as opposed to "sticking-to on the way by"
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Old 01-07-2010, 11:27 AM   #3 (permalink)
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Several of those vehicles' "snow-aero" was influenced by other factors than the straight flow and existing vehicle shape...

While the photos are interesting, they're not scientifically viable at all.

However, wind deposition can show the most aerodynamic shape for a dense object over time. A long time, usually.

Also, without knowing the approximate wind speed when those shapes were produced, it's impossible to know whether or not the shapes would be ideal for a specific speed over another. Average wind speed creates differing deposition shapes, and is still affected by other factors, such as sheer direction and variable speed, as well as the presence of objects which might create resonance at a given speed, or compress flow between the object of resonance and the object of deposition, which would change the flow profile, and thus, the shape of the deposit.
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Old 01-07-2010, 07:22 PM   #4 (permalink)
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Awesome pics and link, thanks. Send more !


Quote:
Originally Posted by Christ View Post
Several of those vehicles' "snow-aero" was influenced by other factors than the straight flow and existing vehicle shape...

While the photos are interesting, they're not scientifically viable at all.

Also, without knowing the approximate wind speed when those shapes were produced, it's impossible to know whether or not the shapes would be ideal for a specific speed over another. Average wind speed creates differing deposition shapes, and is still affected by other factors, such as sheer direction and variable speed, as well as the presence of objects which might create resonance at a given speed, or compress flow between the object of resonance and the object of deposition, which would change the flow profile, and thus, the shape of the deposit.
Why there are unknown variables (some were influenced by the vehicle in front or behind) the results do agree with testing here and by Hucho.
Note the obvious Kamm effect on the cars. The minivan looks a heck of a lot like "AndrewJ"'s Civic doesn't it????
The places where the wind creates high pressure zones will errode the snow and low pressure zones will cause the wind to slow allowing the snow to stick.
This is a step up from "dirt testing" i guess


"Resonance" ???? What the heck, I thought resonance only occurred within a tract or body not open atmosphere. Are you suggesting they could be skewed by aeroelastic flutter?
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Last edited by JasonG; 01-07-2010 at 07:26 PM.. Reason: spellin'
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Old 01-07-2010, 09:23 PM   #5 (permalink)
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Resonance may be the wrong word there.

The effect I meant to describe is the oscillation that occurs behind an object in it's wake. If that oscillation happened near a vehicle during the formation of the wind sculpture, it would have affected the actual airflow and deposit sites.

Just because the shape "looks" like it matches something you've seen on here and in Hucho/other books, doesn't make it ideal.
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Old 01-08-2010, 12:14 PM   #6 (permalink)
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Come on Mother Nature! No wheel skirts?
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Old 01-08-2010, 04:15 PM   #7 (permalink)
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Quote:
Originally Posted by jesse.rizzo View Post
Come on Mother Nature! No wheel skirts?
I was kinda wondering the same. Here's one that has a 'flexible' skirt design.



http://farm3.static.flickr.com/2374/...904dc0784b.jpg
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Old 01-08-2010, 05:58 PM   #8 (permalink)
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Here's my contribution...

I think the ZX2 (Blue Car) looks a bit like an Insight!
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Old 01-08-2010, 07:10 PM   #9 (permalink)
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I liked it how the honda civic ended up looking like the new CRZ in side profile.

Snowmod:
http://cache-03.gawkerassets.com/ass...onda_civic.jpg
CRZ:
http://www.zcars.com.au/images/honda-crz-concept51.jpg

These kind of look like someone glued polystyrene foam all over the car then carved it into shape, which I wondered about doing some day, perhaps with a old clunker, just to see if it works.
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Old 01-08-2010, 07:39 PM   #10 (permalink)
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There's another garage ecomodding technique someone could try. Lather release, Vaseline, on base/donor Honda coupe car. Cover with visqueen plastic. Boxed out with cardboard fences. Fill with foam blocks. Spray foam insulation to fill spaces & gaps to desired 'billet' form. Set. See snow CRZ sample. Fabricate 'hot wire' slicer & carve out desired form. Two-part putty finish, proper surface, prime & paint. For aero testing only.

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