A Preliminary Experiment of Nearshore Current Generated Due to Transverse Phase Differences

Abstract

The vorticity generation due to the ends of wave crests and its resultant rip current have been studied (Johnson and Pattiaratchi, 2006; Clark et al., 2012; Choi et al., 2015; Peregrine, 1998; Postacchini et al., 2014). Recently, a laboratory experiment was conducted to observe rip currents formed between the ends of breaking wave crests (Choi and Roh, 2020) by using the wave generation method of pseudo intersecting wave trains. In this method, regular waves were generated by running two parts of wave maker out of phase. Their pseudo intersecting wave trains was compared with the intersecting wave trains generated by regular waves having the same wave period and the slightly different two wave directions. However, the pseudo intersecting wave trains, i.e., out-of-phase wave trains, could be formed in the field by the transformation of long-crest waves propagating over a specific change of topography in an intermediate water depth, for example, a submerged semi-infinite straight seamount range parallel to the shoreline. The long-crest wave train can be divided into two wave trains with phase difference because of the different wave speeds over the end of the submerged structure. To understand the evolution process of nearshore currents generated due to transverse phase differences, a laboratory experiment was planned. This study showed the preliminary laboratory experiments in which two wave trains with phase differences and its resultant nearshore currents were observed using the optical flow method.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/SaMl6rspZmw