Flow characteristics of the rip current system adjacent to a coastal vertical structure for irregular waves

• Published in: Ocean engineering 2024-11, Vol.312, p.119128, Article 119128
• Main Authors: Xu, Jie, Yan, Sheng, Zou, Zhi-li, Liu, Zhongbo, Wang, Yan, Chang, Cheng-shu, Wang, Zhao-wei, You, Zai-jin
• Format: Article
• Language: English
• Subjects: Crossing waves; Irregular waves; Lateral flow; Rip currents; Single-vortex
• ISSN: 0029-8018
• DOI: 10.1016/j.oceaneng.2024.119128

Rip currents are common hazards found on many beaches around the world. The present research examines the rip current flow features adjacent to a coastal vertical structure with total reflection function to the incident waves. The laboratory experiments were conducted over the planar beach for both regular and irregular waves to explore the specific phenomenon for the irregular waves, and a higher-order Boussinesq equation model was adopted in the simulations to analyze the formation mechanism of the flow features. The study results show that, the standing wave pattern for the irregular wave is much weaker than that for the regular wave with inducing only one apparent node rip at the first node line in the reflection wave area. Moreover, the specific “single-vortex” flow pattern was formed in the crossing wave field for the irregular wave tests. This specific flow pattern is found essentially induced by the larger wave reflection rate of the vertical structure, which leads to the strong lateral flow against the downstream longshore current. This specific flow pattern prefers to present for the smaller wave incident angles and larger wave heights and periods, and leads to the feeding flow volume rates discharged more in the form of lateral flow. The C-shaped lateral flow is found mainly induced by the longshore gradient of the wave set-up instead of the non-uniform wave radiation stress nearshore. •Rip current system adjacent to a coastal structure consists of the deflection rip and one node rip for irregular waves.•The specific “single-vortex” flow pattern in the rip current system was found for the irregular waves.•This “single-vortex” flow pattern presents for the smaller wave incident angles and larger wave heights and periods.•The “single-vortex” flow pattern leads to the feeding flow volume rates discharged more in the form of lateral flow.•The formation of the C-shaped lateral flow is found mainly due to the longshore gradient of the mean water level.