Numerical Model for Wave Pressure Distributions

A mathematical model based on the wave-equation which governs the propagation of small amplitude pressure disturbances through a fluid is used to compute the temporal and spatial variation of impact or shock pressure against vertical wall subjected to breaking wave action. A separate development using conservation of momentum principles results in an equation for the maximum pressure in terms of both breaker characteristics and the time required for the pressure in terms of both breaker characteristics and the time required for the pressure to reach its maximum value. Experiments indicate the existence of two types of impact pressure. Significant impact pressures act over large areas of a structure simultaneously while ordinary impact pressures are more localized. The role of air in decreasing the magnitude of the maximum pressure and in retarding the propagation of the pressure disturbance appears important as the model and data compare favorably when c = 400 fps. This reduction in the sonic velocity through a mixture of air and water will occur with only a 1% volume of entrained air.