Buffeting

[1] Severe, pulsating force of wind. When you drive in a convertible with the top down, you will often experience this buffeting action of the wind. It is also noticeable when a vehicle is driven quickly with the windows down.
[2] An irregular oscillation of any part of an aircraft, caused and maintained by an eddying wake from some other part; commonly, tail buffeting in the downwash of the main plane, which gives warning of the approach of the stall.