Rip Current Dynamics Around Detached Breakwaters

Analysis of Wind Driven Current in Ishikari Bay and Nearshore Current at Ishikari-Hama Beach, Japan

“…Figures show that the rip current generated at the point ①, and the current velocity was about 0.15 m/s. The occurrence situation of the rip current about the wave height was similar to the other example (Inukai, 2015 and2017). However, after flowing out to the offshore, the current velocity changed to about 0.19 m/s, and the current direction changed to SW.…”

“…The wavelength of the cups is about 200 m. Furthremore, Zenibako beach is the sandy coast that has the 200m wavelength cusp topography, and the several offshore breakwaters are set at off the beach. The past our research (Inukai, 2015 and2017) confirmed that such cusp topography was formed by waves, and the nearshore current (include the rip current) occurs at these beaches.…”

“…During conducting the survey, we confirmed the occurrence of a rip current at point ➀ and point ➁ (Figure 3). We visualized the rip current by Inukai's method (Inukai, 2015(Inukai, , 2017. In this method, we pigmented the current by the water colorant, and we got the aerial photograph by Unmanned Aerial Vehicle (UAV).…”

“…When the field survey was conducted, the sea water colorant was sprayed and the diffusion situation was observed. Therefore, we modified the model to be able to simulate the diffusion (Inukai, 2015(Inukai, , 2017. Specifically, this model simulates the diffusion process with Boussinesq equation and the continuous equation at each calculate time step.…”