I've wondered for quite some time now the effects of spoilers and body kits on the aerodynamics of my car. It all started with my old car, Maxima, when I read somewhere that the OEM spoiler actually reduced the CD by 0.01. This didn't quite make sense to me, as I would imagine the spoiler creates slightly more turbulence and thereby decreases the CD. Anyways, since then I've had a decent amount of experience with some CAD modeling programs, as well as CFD (computational fluid dynamics) program (Fluent that is). Seeing as I have absolutely nothing to do today at work (and that I FINALLY finished college yesterday... WOOHOO) I've been messing around with a simple 2D aero analysis of an approximation of my car. Over the next couple weeks I actually plan to take detailed measurements of my own car and model it (probably just in 2D), then "add on" a body kits and spoilers to get a feel for how those items affect the aerodynamics of the car at different speeds (and by how much at those different speeds).

Thought some of you might take an interest in this, if nothing else I'll have some cool pictures of an approximation of our cars in a "wind tunnel" if you will.

At present, my model is going through iterations in Fluent, probably have up some cool graphics after lunch here.

If by chance anyone has a more accurate CAD model of a TL (or any other car for that matter), lemme know, it would be fairly easy to run thru Fluent.

 

Here's a preliminary picture of what I'm getting. The speed of the car is 45mph, and I've plotted contours for air velocity. Red and yellow zones are areas above 45 mph, blue zones are below 45 mph. Notice the small area of essentially zero velocity on the front bumper, and then the turbulence areas off the rear of the car. I'm mostly interested in how those rear turbulence areas change with body kit additions and spoiler additions at various speeds.

Yes, I'm this bored at work

 

looks pretty cool... tho most ppl here get the kits cuz they make the car look that much better... but looks interesting. keep goin if you gots the time

 

I 100% agree the kits look great, I would also put one on purely for the looks. But the technical side of me has always wondered what how the aerodynamics changes with the kits on. That and I like the pictures Fluent spits out

 

Since ricers liked the double decker wing spoilers of yesteryear, model one of those and see what results you get.

 

hahaha i intend to. maybe i'll go post it on a civic forum too, seeing as i can guarantee the results will be larger turbulence, more drag force, and possibly less weight on the front wheels... that'll be next week's project

 

Updated velocity graph - this is at 65 mph, no body kit, no spoiler (still an approximated TL-S 2002). I have a 350Z all drawn up exactly to scale, and over the next week or two going to take measurements on my car to draw it more accurately, then see what kind of changes I get with spoilers and bodykits.

If nothin else, the pictures are pretty cool!



Here is a graph showing the pressure distribution, also at 65 mph. High pressure right up front, low under car, lowest is seen right at the top of the roof, and then more low off the rear of the car. The high pressure (red) in the bottom right corner is not actually there, I have to tweak something in my boundary conditions to fix that up.

 

thats awesome man- i'm def. interested! Does anybody know the factory c/d numbers for our cars?

 

Congrats on graduating, and its obvious you got some mad skillz with your degree. Where'd you go and what'd you study?

I agree that the body kit and wing are probably just for looks. I highly doubt Honda would do wind tunnel testing when designing the aero parts, but they sure as hell probably did focus groups to see which body kit and wing design looked good.

 

i'm not sure what the factory stated CD is... the program I was using (Fluent) won't directly spit out a drag coefficient, but when I get some more time I can export my results into another program and figure out the drag forces...

probly be a couple weeks before i update this thread too, goin away skiing glad to see a couple of ya are interested tho!

 

Thanks! I graduated from UConn with a Mechanical Engineering degree.

I agree Honda probably didn't do any wind tunnel testing on on the body kits, but I think they might help slightly w/aerodynamics, i'll find out eventually tho.