Surf-Zone Hydrodynamics

Abstract

Review paper on the recent progress in the field of wave modelling in the surf zone. The authors have the following concluding remarks (taken directly from the rapport): Wave breaking provides the forcing for larger scale motions in the surf zone. It is therefore probably both somewhat ironic as well as unfortunate that at the present time there exists no satisfactory theory to describe breaking and broken waves in the surf zone. This is currently a topic of intense research interest and we are confident that substantial progress will be made in the near future. While our overall understanding of wave-induced nearshore circulations seems to be fairly sound, there are a number of phenomena that clearly require further study. These include, but are not limited to, quantitatively accurate predictions of rip currents; the predictions of longshore currents on barred beaches; and the importance of alongshore inhomogenieties on nearshore circulations. Once again, these topics are currently being pursued by a number of investigators, and we expect considerable progress in the near future. Recent work has demonstrated that the surf zone is an important region for the generation of infragravity motions. While the present indications are that a substantial fraction of the infragravity energy seems to be generated in and near the surf zone, the existing models of surf zone generation of infragravity motions have not been verified. Shear waves seem to be amenable to an interpretation as a manifestation of an instability of the longshore current. Ongoing work on the nonlinear development of the instability and the importance of wave group forcing on these motions promises to yield interesting results. In conclusion, the subject of surf zone hydrodynamics is at an exciting stage of development right now and we expect that many of the issues will be clarified in the near future. We may also expect that the ongoing and future work will discover phenomena which we are currently unaware of.