Improving flow behind side mirrors

[JulianEdgar]

Small rubber door stops...



...cut up...



...to form small vortex generators.




Placed between mirror and door on W212 Mercedes...



...and tuft tested.



Whiteboard marker used on glass to show tuft behaviour.



Solid lines show arcs within which tufts were moving without VG. Dotted lines show behaviour after VG - much steadier, showing better flow attachment. Note also the better flow direction.

[JulianEdgar]

So I don't think that this would give a reduction in drag even remotely able to to be measured. However, nice to achieve better flow attachment at basically zero cost and effort.

I also think that in some cars, there should be a noticeable reduction in aero noise. (Not on the Mercedes, though - it has thick glass.)

[JulianEdgar]

Without and then with.