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Shock wave visualized over the wing of an airplane
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Video Source: www.youtube.com/watch?v=g4MQqf8wPos
This video shows a shock wave that forms over the wing of a commercial airplane in transonic flight. The video was captured by a passenger using an iphone camera through the window of the plane. The plane is an A320 and its estimated cruise Mach number was Mach 0.78. The shock is made visible, albeit only on the surface of the wing, by the shadowgraph effect -- i.e., the shock casts a 'shadow' by bending the light rays from the sun. See http://en.wikipedia.org/wiki/Shadowgraph for more information on the shadowgraph effect. The shock wave is unsteady (moves back and forth) because it interacts with the turbulent boundary layer that forms on the wing.
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