Laboratory and numerical study of solitary wave impact on a vertical wall mounted on the reef flat with bedform roughness

A series of two-dimensional flume experiments and Reynolds-averaged Navier–Stokes (RANS) simulations have been carried out to investigate the effects of bedform roughness on solitary wave propagation and its impact on the vertical wall in fringing reef profiles. Three water depths and four bedform roughness arrangements are taken into consideration to model different frictional fringing reef configurations. The wave transformation along the flume and the bore impacts on the vertical wall are measured by wave gauges and pressure transducers, respectively. The RANS model is well validated with the experimental data and helps to assist in understanding the main hydrodynamic evolution. Compared to the control tests with a smooth reef flat, bedform roughness decreases the effective depth for wave propagation and enhances wave reflection, thus dissipating the wave height along the reef flat and subsequently reducing the total force on the vertical wall. Owing to the combination of frictional effects and wave reflection, BF3 (bedform roughness configuration with roughness height k = 0.04 m and spacing λ = 0.4 m) most effectively protects the ending wall from wave impact. Moreover, the existing formulas proposed in smooth reef profiles reported in recent research [Fang et al., “Experiment and RANS modeling of solitary wave impact on a vertical wall mounted on a reef flat,” Ocean Eng. 244, 110384 (2022).] well fit the maximum pressure distribution and total force on the vertical wall in bedform roughness configurations.