THE PRESSURE FIELD DUE TO STEEP WATER WAVES INCIDENT ON A VERTICAL WALL

D.H. Peregrine, M.E. Topliss

Abstract


The entrained air present when a wave impacts upon a vertical wall is modelled. A numerical boundary-integral method is applied, with appropriate initial conditions giving a prescribed surface profile and corresponding velocity potential, to model an overturning wave trapping a single air pocket between the oncoming wave front and the vertical wall. The resulting detailed computations provide suitable initial parameters for a simple theoretical model of the trapped air pocket as described in Topliss, Cooker & Peregrine (1992). The fundamental frequencies, and pressures on the impact wall due to the bubble can thus be estimated from the numerical computations. Video frames of small-scale experiments by Hattori & Arami (1992 and private communications) are also examined in detail and similar use of the model provides further pressure estimates. The resulting frequencies and maximum pressures are compared with the measured values. The peak pressures on the impact wall are within 30% of those measured and the frequencies are generally closer. Scaling with wave size is also discussed.

Keywords


vertical wall; pressure field; pressure; steep waves

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