Effect of Seabed Geometry on the Hydrodynamic Performance of a Thick Wavy Porous Barrier

Abstract

This study evaluates the physical mechanisms of incident waves as they interact with a porous wavy barrier of finite thickness. A wave-trapping chamber is formed between the thick wavy barrier (TWB) and partially reflecting seawall (PRS). The effect of seabed undulations is incorporated into the wave-trapping analysis of the TWB. The boundary value problem proposed in this study is solved using a multidomain boundary element method within the context of linear potential flow theory. Coefficients such as reflection, runup, horizontal force on PRS, and vertical force on TWB are examined for various structural configurations. The position of seabed undulations is analyzed for four scenarios: i) seabed undulations upwave of the wavy barrier with a trapping chamber, ii) seabed undulations upwave of the wavy barrier without a trapping chamber, iii) seabed undulations underneath the wavy barrier with a trapping chamber, and iv) seabed undulations beneath the wavy barrier without a trapping chamber. The study results are compared with known results to verify their accuracy. The effects of PRS, TWB porosity, trapping chamber, plate thickness, seabed type, and submergence depth on hydrodynamic coefficients are analyzed against relative water depth. The study reveals that the introduction of a porous TWB with a trapping chamber results in minimal hydrodynamic coefficients (reduced reflection and force on a wall) compared to a rigid TWB without a trapping chamber. A comparison of various seabeds is reported for all combinations of TWB with a chamber. The sloping seabed upwave of the barrier with a trapping chamber, 20% plate porosity, and 50% wall reflection at an appropriate submergence depth could replace gravity-type breakwaters in deeper waters. This study holds great potential for analyzing wave trapping coefficients by TWB to provide an effective coastal protection system.

Keywords

Wave trapping / Thick wavy plate / Porosity / Partially reflecting wall / Multidomain boundary element method / Undulated seabed

RIGHTS & PERMISSIONS

Harbin Engineering University and Springer-Verlag GmbH Germany, part of Springer Nature