Toshiki OOHASHI
Fundamental Numerical Study on Generation of Rip Currents
Tokuzo HOSOYAMADA
Every year, a lot of swimming accidents occur in Japan. The seashore accidents are considered to be caused by rip currents. Rip current is a strong flow with the direction from shore into offshore. Moreover, it is known that the rip current is very difficult flow because the place of occurrence and the scale are different based on the incident wave condition and the weather condition. However, the generation mechanism of the rip current has not been clarified fully.
In this study, numerical simulation of rip current is carryied out using two-dimensional finite difference model based on the Boussinesq equations. Virtual topography which has artificial cusp topography was used to understand basic mechanism of rip current. Wave is generated at the offshore boundary with the various wave directional conditions and then relationship of wave and rip currents around shore are examined. The characteristics of incident wave are estimated using the wave of normal circumstances.
The simulation results show that rip current occurred at the cusp if the water level is different. Moreover, the significant wave period and the significant wave high are factors that influence it at the maximum flow velocity of the rip current. Moreover, the index from which the maximum flow velocity of the rip current corresponding to geographical features was able to be requested was able to be shown by quantitatively evaluating flow velocity.
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