Funky aerodynamics

[ggodman]

Here is an interesting experiment in aerodynamics for my fellow leaf owners.

Today I was sitting a lunch and had the windows open, rolled up all but the drivers rear window for some reason (Don't know why, just happened), started going and once I hit speed it is a very fast thump thump thump, could not figure it out for a minute but then I did it seemed strange, just thought it was interesting.

 

[darelldd]

Sounds quite similar to what happens in the Prius.

 

[Nekota]

I think that happens with most any vehicle - a resonating cavity created by shedding vortexes from the open window. It's how flutes make their sound.

Examples -->
http://www.ansys.com/staticassets/ANSYS/staticassets/resourcelibrary/confpaper/2006-Int-ANSYS-Conf-253.pdf

http://www.exa.com/pages/applications/aeroacoustics.html

Search for Rear Window Buffeting or Wind Throb for many other examples.

 

[garygid]

The car acts as a low frequency resonator if the side-rear windows are open just the right amount. Like a flute.

There is a whole thread on the whump, whump vibrations.