View Single Post
Old 12-11-2019, 01:39 AM   #3 (permalink)
Ecomodding amateur
M_a_t_t's Avatar
Join Date: Nov 2015
Location: Indiana
Posts: 215

The Van - '95 Chevy Astro Cl
Team Chevy
90 day: 16.39 mpg (US)

The new bike - '17 Kawasaki Versys X 300 abs
90 day: 51.71 mpg (US)

The Mercury - '95 Mercury Tracer Trio
Team Ford
90 day: 34.33 mpg (US)
Thanks: 28
Thanked 66 Times in 48 Posts
Originally Posted by freebeard View Post
Is the ground plane moving? Are the wheels represented?

They interoperate, or something. There should be some algorithm to combine the results.

Is this analyzing a 2D plane though the centerline of the vehicle? If so it's meaningless. The entire 3D form is necessary.

The only difference I see is the speed and pressure. What hood height difference is there? Once again, the 3D form is significant. A Jeep and a VW Beetle have flat windshields at a similar angle. But the Jeep's is square while the Beetle has a teardrop that has been truncated at the front. It's body is widest at the C-pillar.

I looked around a bit. You may find answers at
1.Ground plane is stationary as well as the wheels. Same as in a wind tunnel.

1.5 Would that algorithm be the cD number or similar?

2. Can you expand on that? Other threads look at 2d profiles, which would be basically the same as a smoke overlay (like in the first post of the wind tunnel thread) and we still can make assumptions based on that data such as how small the vortex at the back of the car is. I just want to try and figure out how much difference it makes and have a plan before trying to make something on the car.

3. Its relatively small. Like 3-4 inches up the windshield. I only put it in the center of the model because thats where the plane is. Jeep and beetles have different approaches though. Jeeps hoods are pretty much parallel to the ground. Ignoring the part at the base of the windshield the beetles is more obtuse.

I will check that out, thanks.

Wind speed set to 25 m/s. velocity instead of pressure.

Wind speed at 25 m/s velocity instead of pressure. It also seems like flow stays attached longer at the back.
At 55 mph, a 10% drag reduction translates to a 5% increase in fuel economy. At 70mph,a 10% drag reduction translates into a 6% increase -Phil Knox (Aerohead), Aerodynamics Seminar #2
Originally Posted by M_a_t_t View Post
My other hobbies have no ROI (making things go fast). So I'm having fun modding my car for better mileage and the side effect is that I save money on gas day to day.
  Reply With Quote