| Title |
Investigation of Characteristics of Rip Current at Haeundae Beach based on Observation Analysis and Numerical Experiments |
| Authors |
윤성범(Yoon, Sung Bum) ; 권석재(Kwon, Seok Jae) ; 배재석(Bae, Jae Soek) ; 최준우(Choi, Junwoo) |
| DOI |
https://doi.org/10.12652/Ksce.2012.32.4B.243 |
| Keywords |
이안류;해운대;관측분석;수치실험 Rip current;Haeundae beach;observation analysis;numerical experiment;COULWAVE |
| Abstract |
To investigate the characteristics of rip current occurring at Haeundae beach, observations obtained from a buoy and a CCTV were analyzed and numerical experiments were conducted. During observed rip-current events, the CCTV images showed that a couple of wave-trains, which are close to regular waves with slightly different directions, propagated to the beach, and wavelet analyses of data from the buoy showed very narrow-banded spectra with a peak frequency. From the evidences, it was inferred that a known mechanism of generating rip current due to the nodal line area of honeycomb-patterned wave crest was one of the significant factors of rip current occurrences of Haeundae beach. The mechanism has been explained by the following: When two wave-trains with slightly different directions propagate to a beach, wave crests of the incident wave-trains form honeycomb pattern due to nonlinear interaction. The nodal lines of honeycomb pattern are developed in the cross-shore direction. And longshore currents flow toward the nodal line area which has very low wave energy. Consequently their mass flux is expelled through the area toward the sea direction. To confirm the generation, numerical experiments were performed using a nonlinear Boussinesq equation model. In the cases with two incident wave-trains with slightly different directions and with a monochromatic wave propagating over a submerged shoal, it was seen that the honeycomb pattern of wave crests was well developed, and thus rip currents were evolved along the nodal lines. |