Lagrangian Acceleration as a Diagnostic for Wave Breaking in the Nearshore Zone

Abstract

This study focuses on evaluating the Lagrangian downward acceleration of fluid particles near the wavecrest as a dynamic criterion for identification of wave breaking in shallow water. The use of the downward acceleration as an indicator for wave breaking goes back to the work of Longuet-Higgins (1963), https://doi.org/10.1017/s0022112063000641 who showed theoretically that the acceleration near the crest of a regular wave is (Formula presented.) for the highest wave in deep water. In the subsequent literature, various other threshold values on the downward acceleration have been suggested based on theoretical or experimental investigations but a general agreement has not been established. Based on stereo imaging of tracer particles in the surf at Sylt, Germany, data analysis, and in-depth visual analysis, it is shown here that this criterion successfully classifies breaking and non-breaking waves in (Formula presented.) of the 99 wave events examined.