On the Disintegration of the Jet in a Plunging Breaker

Abstract

An inviscid mechanism is proposed for the breakup of the jet in a plunging surface wave. Streamwise perturbations of the original surface are shown to grow rapidly owing to stretching of the thin jet and to drastic reduction in the normal pressure gradient. This converts transverse gravity waves into almost pure capillary waves. Conservation of wave action for the perturbations then implies a strong increase in the perturbation amplitude.