Numerical investigation of rip currents near a barred beach induced by irregular waves

Abstract

Rip currents pose a common natural hazard at coastal tourist beaches, presenting a significant threat to the safety of beachgoers and beach management. To better understand the characteristics of rip currents, particularly those induced by irregular waves on a barred beach, this study utilized a Boussinesq-type, phase-resolving hydrodynamic model for numerical simulations. We investigated various factors, including significant wave height, peak period, incident angle, and bottom friction, to assess their impact on rip currents formation. The results of our research reveal some key insights. Firstly, an increase in significant wave height and peak period fosters the development of rip currents. However, beyond a certain threshold, the intensity of the rip currents decreases. Conversely, a larger incident angle tends to reduce the intensity of rip currents. Additionally, higher bottom friction leads to increased energy dissipation during wave propagation, consequently resulting in decreased rip currents intensity. In an effort to create a more precise representation of real sea conditions, multi-directional waves were employed as incident waves in this study. An analysis of different standard deviations of directional distributions revealed that as the directional spread of incident waves widens, the waves become more susceptible to breaking, ultimately leading to a reduction in the intensity of rip currents.