Abstract
A Jarlan-type perforated caisson consisted of a perforated front wall, a solid rear wall, and a wave-absorbing chamber between them. The wave-absorbing chamber was the main feature of the perforated caisson, and its width had a great effect on wave attenuation performance. In this study, a larger range of the wave-absorbing chamber width was observed in model experiments to investigate the effect on wave attenuation performance including the reflection coefficients and the horizontal wave forces of a perforated caisson sitting on a rubble-mound foundation. A resistance-type porosity numerical model based on the volume-averaged Reynolds-averaged Navier–Stokes (VARANS) equations was validated by comparing the present results with those of previously reported and present experiments. The validated numerical model was then used for extended research. It was found that the reflection coefficients, the total horizontal wave force, and its components all tended to oscillate in a decrease ⟶ increase ⟶ decrease manner with increasing the wave-absorbing chamber width. The reflection coefficients and wave forces acting on both sides of the perforated front wall were found to be synchronized regardless of perforation ratio or the rubble-mound foundation height.
Highlights
Perforated caissons were first proposed by Jarlan [1] in the 1960s
Model experiments were carried out to study the effects of a large range of the wave-absorbing chamber width on the wave attenuation performance of a perforated caisson sitting on a rubble-mound foundation
A porosity-type numerical model based on volumeaveraged Reynolds-averaged Navier–Stokes (VARANS) equations was validated by comparing with the existing and present model experiments. e validated numerical model was used for extended research. e conclusions are given as follows: (i) e resistance-type porosity model used in the present research took into account the porosity of the rubble-mound foundation and the fluid viscosity. e numerical results were in good agreement with the existing and present model experiments. erefore, the numerical model could be used to further study the wave interaction with a perforated caisson sitting on a rubble-mound foundation
Summary
Perforated caissons were first proposed by Jarlan [1] in the 1960s. Some other new types of caisson were proposed and studied in recent years [9, 10]. A Jarlan-type perforated caisson consisted of a perforated front wall, a solid rear wall, and a wave-absorbing chamber between them. When the incident wave overlapped with the reflected waves from the perforated front wall and the solid rear wall, the wave energy can be greatly reduced. Compared with the traditional caisson, a perforated caisson reduced reflection coefficients and the wave forces. A perforated caisson had the advantages of easy construction and a wide range of applications, making it a key structure in coastal and port engineering
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