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Old 07-11-2008, 01:34 PM   #11 (permalink)
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BTW, do use the dimensions he gave, and if your creating your own silhouettes, do not use any anti-aliasing or it screws up the uploaded image.


^it's still processing, but shouldnt take long

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"All I know about music is that not many people ever really hear it. [...] But the man who creates the music is hearing something else, is dealing with the roar rising from the void and imposing order on it as it hits the air. What is evoked in him, then, is of another order, more terrible because it has no words, and triumphant, too, for the same reason. And his triumph, when he triumphs, is ours." -Sonny's Blues

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Old 07-11-2008, 02:00 PM   #12 (permalink)
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thirdman -

THANK YOU!

Can someone post good city/highway settings for the parameters?

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Old 07-11-2008, 03:58 PM   #13 (permalink)
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Quote:
Originally Posted by texanidiot25 View Post


So what are the best numbers?
Numbers to use:
L* = effective diameter of your car [1990 Firebird: (72.4" (width) * 49.8" (height) )^0.5 = ~60" = 1.53 m]
v = velocity [50 mph = 22.35 m/s]
'nu' = 1.6*10^-5 m^2/s

Thus: Re = 1.53 * 22.35 / 1.6*10^-5 = ~2,100,000

(*) Note:
A better reference would be the effective diameter rather than its length, as length is used for flat plates.

Now, on to making 2-D renditions of vehicles I have once owned...
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Old 07-11-2008, 04:05 PM   #14 (permalink)
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Quote:
Originally Posted by co_driver View Post
Numbers to use:
L* = effective diameter of your car [1990 Firebird: (72.4" (width) * 49.8" (height) )^0.5 = ~60" = 1.53 m]
v = velocity [50 mph = 22.35 m/s]
'nu' = 1.6*10^-5 m^2/s

Thus: Re = 1.53 * 22.35 / 1.6*10^-5 = ~2,100,000

(*) Note:
A better reference would be the effective diameter rather than its length, as length is used for flat plates.

Now, on to making 2-D renditions of vehicles I have once owned...
Alright, thanks!

Here's a few more I made out of boredom. One is my friend's 04 Avalanch, and for kicks I did my '69 CST10. Though these are with the default numbers, and the windspeed one at .1


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"All I know about music is that not many people ever really hear it. [...] But the man who creates the music is hearing something else, is dealing with the roar rising from the void and imposing order on it as it hits the air. What is evoked in him, then, is of another order, more terrible because it has no words, and triumphant, too, for the same reason. And his triumph, when he triumphs, is ours." -Sonny's Blues
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Old 07-11-2008, 05:13 PM   #15 (permalink)
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Does this determine flow based on a flat 2d plane, or does it also take the width of the vehicle into account? Wondering if when making a truck shape, should the open bed be taken into account...
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Old 07-11-2008, 09:16 PM   #16 (permalink)
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Yes, it only does 2D calculations. It has no idea that the bed of your truck is empty or that there are dangly bits all over the place under the hood.

If you want that kind of data, though, you could do cross-sectional images (ie, exclude the sides of the bed)
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Old 07-11-2008, 09:18 PM   #17 (permalink)
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Hello -

Sooooooo, what should dt be for 35 MPH and 55 MPH?

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Old 07-11-2008, 09:53 PM   #18 (permalink)
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Man this program has a total freakout when I set the RE to 2,100,000 and then the dt to .02.

Was testing the flow of air from a lower scoop (like it had for the radiator) toa heat extracter hood vent like some T/As had.
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"All I know about music is that not many people ever really hear it. [...] But the man who creates the music is hearing something else, is dealing with the roar rising from the void and imposing order on it as it hits the air. What is evoked in him, then, is of another order, more terrible because it has no words, and triumphant, too, for the same reason. And his triumph, when he triumphs, is ours." -Sonny's Blues
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Old 07-11-2008, 10:48 PM   #19 (permalink)
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Dammit, I got all the BMP's made but my mac won't play the video files back to me.

Time to do some detective work on finding the right codecs or whatnot.
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Old 07-12-2008, 12:07 AM   #20 (permalink)
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For a pickup truck I would leave off the side walls of the bed. Draw the Cab, the floor of the bed, and the tailgate. Otherwise you don't see the effect of the vortex in the bed. Leaving them on shows what it would look like with a tonneau cover.

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