The Diffraction of Strong Shock Waves

The pseudostationary flow field resulting from diffraction of a strong shock in air over a convex corner has been investigated with the shock tube and interferometer. Only when the shock has turned nearly 180^∘{}, is it observed to become vanishingly weak. A potential flow theory for part of the field is inadequate to predict the extent of a Prandtl-Meyer expansion around the corner. Viscous forces produce a boundary layer which causes the flow to separate at the corner with significant changes in the density field as a result.