The diffraction of blast. I

The behaviour of a plane shock, of any strength, travelling along a wall, when it reaches a corner where the wall turns through a small angle δ, is investigated mathematically by use of a linearized theory of anisentropic flow (§§ 2 to 5). At a convex corner pure diffraction occurs; at a concave corner Mach reflexion (§8). The shape of the shock (§6) and the pressure distribution over the wall (§7) are calculated for a variety of shock Mach numbers from 1 to ∞. The connexion, for weak shocks, with acoustic theory, is displayed (§9). The work will be used in later parts to assist in a hypothetical description of the flow when δ is not small.