# 12.7: Flat Body with an Angle of Attack

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Fig. 12.28 The definition of attack angle for the Prandtl–Meyer function.

Previously, the thickness of a body was shown to have a drag. Now, a body with zero thickness but with an angle of attack will be examined. As opposed to the thickness of the body, in addition to the drag, the body also obtains lift. Again, the slip condition is such that the pressure in region $$5$$ and $$7$$ are the same, and additionally the direction of the velocity must be the same. As before, the magnitude of the velocity will be different between the two regions.