The analogy between the formation of large amplitude waves (hydraulic jumps) on the surface of shallow flowing water, and shock waves in supersonic air flow is well-known. In addition to the correspondence between the wave patterns the variation in water depth can be related to the pressure distribution.

This “hydraulic analogy” is usually demonstrated in the laboratory in a tank which produces a shallow flow of water over a horizontal surface, on which the appropriately shaped body is mounted. The resulting stationary wave patterns may then be examined. Fig. 1 shows a typical bow-wave on a double-wedge.