Linking reduced breaking crest speeds to unsteady nonlinear water wave group behavior

TL;DR

This paper reveals a universal wave-crest slowdown mechanism in unsteady deep water wave groups, showing that crest speeds decrease before breaking, which is validated through simulations, laboratory, and field observations.

Contribution

It introduces a new understanding of wave-crest slowdown in unsteady water wave groups, supported by nonlinear computations and extensive empirical data.

Findings

Crest speeds slow down significantly before breaking.

Wave behavior is consistent across simulations, laboratory, and field data.

The slowdown mechanism is likely universal in natural dispersive wave systems.

Abstract

Observations show that maximally-steep breaking water wave crest speeds are much slower than expected. We report a wave-crest slowdown mechanism generic to unsteady propagating deep water wave groups. Our fully nonlinear computations show that just prior to reaching its maximum height, each wave crest slows down significantly and either breaks at this reduced speed, or accelerates forward unbroken. This finding is validated in our extensive laboratory and field observations. This behavior appears to be generic to unsteady dispersive wave groups in other natural systems.