More drag reduction studies

[Cd]

Hey Euro, I like your thinking !
Clever idea using a bike rack disguise !

[California98Civic]

Originally Posted by Cd

Hey Euro, I like your thinking !
Clever idea using a bike rack disguise !

Me too.

Originally Posted by Cd

( Actually, to be fair it should be mentioned that Paulu made note of the studies posted here on page 2 of the original thread - but its good to have a dedicated thread on this. )

I did note it, and linked to his post, in the OP of this thread. I was unaware of his post at first. When I saw it, I edited this post and also asked the moderators to consider merging the threads, but Metro thought there was enough difference to keep them separate. My OP was mostly interested in expanded detail on the specific drag reductions attained through the box cavity designs. That was not part of what paulu noted.

[Sven7]

I've been thinking about this some more. Do you think a sedan owner could create a plexiglass baseplate sticking up vertically from the trunk edge, essentially creating a phantom Kammback? This would be less intrusive than making the trunk unusable but would it give meaningful drag reduction?

[PaleMelanesian]

Originally Posted by drmiller100

Research

This article is IMPORTANT. I recommend you save it, read it, and learn it.

This article is saying you can reduce drag 40 percent by making a tail. And the tail does not have to be very long.

And according to them, 20 degrees is about the absolute max, and even at that you are going to have problems with the bottom, but it is still worth it.

This article is worth SAVING.

Link is broken. Anyone have a copy?

[christofoo]

Originally Posted by PaleMelanesian

Link is broken. Anyone have a copy?

Looks like Coventry broke all the links, and I'm not sure how to find any papers anywhere on their site - which is sad, I haven't read them.

It looks like I had some luck searching the web for a few titles though:
http://www2.warwick.ac.uk/fac/sci/wm...baseplates.pdf
http://www2.warwick.ac.uk/fac/sci/wm...simplebody.pdf

[kach22i]

Here is one specific to drag on electric vehicles, also covers wheel openings (and more):

http://www2.warwick.ac.uk/fac/sci/wm...tationws12.pdf

[California98Civic]

Originally Posted by kach22i

Here is one specific to drag on electric vehicles, also covers wheel openings (and more):

http://www2.warwick.ac.uk/fac/sci/wm...tationws12.pdf

On page 10 their scale model testing shows a tiny benefit for "blanking" the wiper cavity. And their biggest benefit was with the rear diffuser.

[christofoo]

Originally Posted by kach22i

Here is one specific to drag on electric vehicles, also covers wheel openings (and more):

http://www2.warwick.ac.uk/fac/sci/wm...tationws12.pdf

Another point I notice in this doc is they used OpenFOAM for CFD - never heard of it, but found it here: The OpenFOAM&#174 Foundation. (I also could have found it just googling 'open source CFD,' though it's nice to know what Universities have chosen for CFD.) OpenFOAM is open source / free, looks easy (for me) to install or build for Linux *not for Windows*... but the learning curve appears very steep. Momentarily I couldn't find an answer to how you import solid objects into the OpenFOAM mesh generator, i.e. from a NURBS or Polygon file format, which is key. But I think I remember some separate open-source projects that stand alone as mesh generators, so I think there is a solution outside the scope of OpenFOAM. (Finally in order to delve into CFD one would have to consider how to setup some correlation between CFD and wind-tunnel data (preferably someone else's published wind-tunnel data), to ensure the computation is configured sensibly. Overall I'm not sure if it's worth the investment of (my) time, but it's always a temptation in the back of my mind... and now I know the name of a viable CFD suite...)

[euromodder]

Originally Posted by PaleMelanesian

Link is broken. Anyone have a copy?

You'll find them here, amongst other stuff:

https://www.dropbox.com/sh/52o49bkru...modder_studies

[PaleMelanesian]

Outstanding! Too bad I can only give you one Thanks for that post.