Author(s): Yuhua Zheng; Xiaoyan Li; Hongwei Zhang; Jiafa Shen And Chuanguo Cheng
Linked Author(s): Yuhua Zheng
Keywords: Reef-type breakwater smoothed particle hydrodynamic spacing ratios bragg resonance wave-induced current
Abstract: The study investigates the characteristics of wave transformation and wave-induced currents over periodically distributed single-row perforated reef-type breakwater (RB) groups with varying spacing under three distinct regular incident wave conditions. Laboratory experiments were conducted to measure wave profiles and heights for RBs positioned without spacing under short-period incident waves. The findings reveal a significant reduction in wave height due to energy dissipation from shoaling effects; however, the waves retained a quasi-symmetrical sinusoidal form and continued propagating forward due to the substantial submergence of the breakwaters. Additionally, a non-reflective numerical wave model was developed using the Smoothed Particle Hydrodynamics (SPH) method and validated against experimental data. This model was utilized to simulate regular wave propagation over RBs with spacing ratios ranging from 0.5 to 3.0. Notably, the interaction between RBs with a spacing ratio of 2.5 and the incident waves induced Bragg resonance under short-period wave conditions (period 1.2 s, wave height 0.04 m), resulting in the most pronounced reflection effect observed. The RB groups generated a wave-induced current circulation that transitioned from near-bottom undertow currents to near-surface onshore currents aligned with the direction of wave propagation. Increased incident wave intensity and reduced spacing between the RB blocks enhanced the strength of this wave-induced circulation. The spacing between RBs serves as a mechanism for adjusting wave energy by altering the phase difference during wave propagation. Specifically, after waves passed through RBs with smaller spacing, the wave energy density shifted from the dominant frequency to higher frequencies, while larger spacing caused the energy to shift from the dominant frequency to lower frequencies.
Year: 2025