Go Back   EcoModder Forum > EcoModding > Aerodynamics
Register Now
 Register Now
 

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 07-14-2008, 11:15 AM   #41 (permalink)
EcoModding Minded
 
Chris D.'s Avatar
 
Join Date: Jan 2008
Location: Eagan, MN
Posts: 667

Lunar Mist - '02 Toyota Tacoma SR5
90 day: 25.31 mpg (US)

Silver Streak - '08 Toyota Corolla S
90 day: 38.25 mpg (US)
Thanks: 67
Thanked 25 Times in 12 Posts
Send a message via AIM to Chris D.
Quote:
Originally Posted by Peakster View Post
You know I was just curious :


hmmm makes me think about trying this..





__________________


  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 07-14-2008, 02:34 PM   #42 (permalink)
EcoModding Lurker
 
Join Date: Jul 2008
Location: NJ land of high auto insurance and pollution
Posts: 12
Thanks: 0
Thanked 0 Times in 0 Posts
This is some cool software!

Uploaded a 2009 Ford Escape Hybrid to my youtube.
  Reply With Quote
Old 07-14-2008, 04:41 PM   #43 (permalink)
Mr. Blue Tape
 
azraelswrd's Avatar
 
Join Date: Jun 2008
Location: Fresno, CA
Posts: 345

AzxA - '06 Scion xA
90 day: 42.72 mpg (US)
Thanks: 0
Thanked 2 Times in 2 Posts
Wow, this program is nice. I knew my car had bad drag but wow... was it really this bad? Yikes!

I'll have to look into that floating parallel spoiler idea.
__________________


My 5 pillars of fuel efficiency:
  • driving style
  • aerodynamics
  • tires
  • weight reduction
  • engine maintenance
  Reply With Quote
Old 07-14-2008, 05:30 PM   #44 (permalink)
Master EcoModder
 
texanidiot25's Avatar
 
Join Date: Jul 2008
Location: Cypress, TX
Posts: 331

Formula - '96 Firebird Formula/Trans-Am
90 day: 19.31 mpg (US)
Thanks: 8
Thanked 31 Times in 18 Posts
Quote:
Originally Posted by i_am_socket View Post
I'm getting some interesting movies using the high Re numbers.

I get a lot of this:


using 2,500,000. Is it supposed to look like that?
Lower the Dt number to around .01, it seems to spaz out with higher Dt numbers. Real psychodelic stuff.
__________________


Lets see how far it can go

"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
  Reply With Quote
Old 07-14-2008, 05:39 PM   #45 (permalink)
EcoModding Lurker
 
adrive7's Avatar
 
Join Date: May 2008
Location: DC Metro
Posts: 48

Ranger - '08 Ford Ranger XL
90 day: 20.73 mpg (US)
Thanks: 0
Thanked 0 Times in 0 Posts
Send a message via AIM to adrive7
Quote:
Originally Posted by i_am_socket View Post
I'm getting some interesting movies using the high Re numbers.

I get a lot of this:


using 2,500,000. Is it supposed to look like that?
I would try adding white area all around the vehicle. Also, get rid of the tires so you can see the air flow under the car. If you increased the time step (dt) take it back down to around .01. It looks like you are seeing effects from the edges of the pictures, but I don't know why it would do that. Adding white area around it should get rid of that problem (if thats what it is)

The Reynolds number is fine.
__________________
Ohio State Baja SAE
  Reply With Quote
Old 07-14-2008, 06:16 PM   #46 (permalink)
Pokémoderator
 
cfg83's Avatar
 
Join Date: Dec 2007
Location: Southern California
Posts: 5,864

1999 Saturn SW2 - '99 Saturn SW2 Wagon
Team Saturn
90 day: 40.49 mpg (US)
Thanks: 439
Thanked 528 Times in 355 Posts
adrive7 -

Quote:
Originally Posted by adrive7 View Post
I would try adding white area all around the vehicle. Also, get rid of the tires so you can see the air flow under the car. If you increased the time step (dt) take it back down to around .01. It looks like you are seeing effects from the edges of the pictures, but I don't know why it would do that. Adding white area around it should get rid of that problem (if thats what it is)

The Reynolds number is fine.
I agree. In my runs, I added a "road" below my "hover-car" and I put some empty space behind the car to analyze the wake that my mods created.

If you put the tires on, I think it is like having "Flintstone Roller" tires, because you are cutting off airflow below the vehicle. I *think* if you want to approximate tires, you could add shallow "bumps" where the tires are. Maybe the compromise is to approximate how much "area" the tires displace below the car and make the "bump" proportional to that. Does that make sense?

I used an Re of 2,500,000 in my second analysis, and I set it to 40 seconds. I also used a 2-bit Bitmap.

CarloSW2
__________________

What's your EPA MPG? Go Here and find out!
American Solar Energy Society
  Reply With Quote
Old 07-16-2008, 09:50 PM   #47 (permalink)
Master EcoModder
 
wagonman76's Avatar
 
Join Date: Jun 2008
Location: Northwest Lower Michigan
Posts: 1,006

Red Car - '89 Chevrolet Celebrity CL 4 door
Team Chevy
90 day: 36.47 mpg (US)

Winter Wagon - '89 Pontiac 6000 LE Wagon
90 day: 28.26 mpg (US)
Thanks: 8
Thanked 17 Times in 16 Posts
This is pretty cool, but I can't play the videos either. My computer at work is the only one with high speed internet and I can't install anything, at least right now. Could someone give me a hand with this one? I copied a side view (pre-airdam) into Autocad and traced around it, then solid filled it, so it was black on white. Wheels off should simulate airflow under the majority of the car.

Attached Images
File Type: bmp CelebProfile2.bmp (16.1 KB, 448 views)
__________________

Winter daily driver, parked most days right now


Summer daily driver
  Reply With Quote
Old 07-16-2008, 10:15 PM   #48 (permalink)
EcoModding Apprentice
 
Join Date: Jan 2008
Location: Chicagoland
Posts: 204

- - '10 Toyota Prius III w/Navi
Thanks: 4
Thanked 11 Times in 11 Posts
Hi All,

This is all very interesting. But its been commented elsewhere what is usabilty of the results? One thing to look at is the flow at the rear. If there is flow upward, then extending the cam back is the thing to do. And if the flow is downward, then doing a diffuser, with some rear belly-panning is the the thing to do. What one wants to do is make the flow go straght back without upward or downward velocity components.

Can somebody do a Prius without wheels ?
  Reply With Quote
Old 07-16-2008, 10:35 PM   #49 (permalink)
Mr. Blue Tape
 
azraelswrd's Avatar
 
Join Date: Jun 2008
Location: Fresno, CA
Posts: 345

AzxA - '06 Scion xA
90 day: 42.72 mpg (US)
Thanks: 0
Thanked 2 Times in 2 Posts
Wagonman



Values I used:

Re = 2,500,000
dt = 0.01
length = 30 sec
cutoff level = 0
__________________


My 5 pillars of fuel efficiency:
  • driving style
  • aerodynamics
  • tires
  • weight reduction
  • engine maintenance
  Reply With Quote
Old 07-17-2008, 12:07 PM   #50 (permalink)
Master EcoModder
 
wagonman76's Avatar
 
Join Date: Jun 2008
Location: Northwest Lower Michigan
Posts: 1,006

Red Car - '89 Chevrolet Celebrity CL 4 door
Team Chevy
90 day: 36.47 mpg (US)

Winter Wagon - '89 Pontiac 6000 LE Wagon
90 day: 28.26 mpg (US)
Thanks: 8
Thanked 17 Times in 16 Posts
Cool, thanks a bunch!

__________________

Winter daily driver, parked most days right now


Summer daily driver
  Reply With Quote
Reply  Post New Thread


Tags
air dam, air flow, simulation, spoiler, wind tunnel

Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
The Mechanism Behind Flow Separation LostCause Aerodynamics 46 07-15-2010 07:38 AM



Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2020, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com