CFD Parameters

[bluetooth]

I am currently using STAR-CCM+ to simulate the airflow around our car, with the eventual goal of developing an undertray and wings for next year's vehicle.

I am running into a small problem with the drag coefficient of the car. My reference area is the approximate frontal area of the car, however I am seeing a Cd~0.9 (which common knowledge tells me is nearly 3 times greater than it should be).

If anybody has any experience with this software and can give me some advice, it would be much appreciated.

Thanks.

[Scott Wordley]

What common knowledge?

The Cd for a mproduction car (ie sedan) is commonly around 0.3.

This is not the case for an open wheel race car, and a CD of 0.9 is not unusual. The body shape can be quite aerodynamics but the open wheels are a killer.

[Ben K]

Originally posted by bluetooth:
I am currently using STAR-CCM+ to simulate the airflow around our car, with the eventual goal of developing an undertray and wings for next year's vehicle.

I am running into a small problem with the drag coefficient of the car. My reference area is the approximate frontal area of the car, however I am seeing a Cd~0.9 (which common knowledge tells me is nearly 3 times greater than it should be).

If anybody has any experience with this software and can give me some advice, it would be much appreciated.

Thanks.

Which team are you part of in Florida?

[Scott Wordley]

Also, when you are comparing winged versus non winged cases, or massively different wing cases where Area is changing a lot, it is much easier simply to work with CD.A and CL.A to define the actual drag and downforce generating capability of the car with speed.

That way you are compare apples with apples, and not confusing matters due to the changing Area.

[Lorenzo Pessa]

Look around the forum, I've published my CFD results some months ago.
Give also a look to some books like Katz, Hucho or similar.