Breaking criterion and characteristics for solitary waves on slopes

Journal of Waterway Port Coastal and Ocean Engineering, 123(3), 102-112

Stephan T. Grilli                         and                   Ib A. Svendsen      and              R. Subramanya

Associate Professor                                           Professor                                     Graduate student
Department of Ocean Eng.                                 Department of Civil Eng.          
niversity of Rhode Island                                    University of Delaware
Narragansett, RI 02882, USA                            Newark, DE 19716, USA

Abstract :  

Shoaling and breaking of solitary waves is computed on slopes 1:100 to 1:8 using an experimentally validated fully nonlinear wave model based on potential flow equations. Characteristics of waves are computed at and beyond the breaking point, and geometric self-similarities of breakers are discussed as a function of wave height and bottom slope. No wave breaks for slopes steeper than 12 deg. A breaking criterion is derived for milder slopes, based on values of a nondimensional slope parameter So. This criterion predicts both whether waves will break or not and which type of breaking will occur (spilling, plunging, or surging). Empirical expressions for the breaking index and for the depth and celerity at breaking are derived based on computations. All results agree well with laboratory experiments. The NSW equations fail to predict these results with sufficient accuracy at the breaking point. Pre-breaking shoaling rates follow a more complex path than previously realized. Post-breaking behaviors exhibit a rapid (non-dissipative) decay, also observed in experiments, associated with a transfer of potential energy into kinetic energy. Wave celerity decreases in this zone of rapid decay.

Keywords :

Solitary wave propagation; wave shoaling; wave breaking; wave runup on beaches; long wave theory; fully nonlinear waves; experimental modeling of waves; numerical modeling of waves; boundary element method.

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