Hydrodynamic analysis of a seaside quarter-circular breakwater with an array of porous cages using DBEM

ABSTRACT

The gravity wave interaction with an array of porous cages in the presence of a seaside submerged quarter-circular porous breakwater (QCPBW) is analyzed within the framework of linearized water wave theory. A quadratic pressure drop is adopted for the wave past the porous structures to capture the effect of wave height on the energy dissipation. The boundary value problem is solved using the iterative Dual Boundary Element Method (DBEM). The numerical code is validated with known results in the literature. One or upto four units of submerged and bottom fixed porous cages are considered. The effect of porosity on QCPBW and porous cages are investigated pragmatically to study the scattering and wave forces. It is found that introducing a single porous cage with 10% porosity at the rear side of a QCPBW with a porosity of 25% can reduce the wave transmission coefficient by about 50% for relative water depth ${\mathrm{k}}_0\mathrm{h}>\pi /3$. Increasing the porosity of the single cage from 10% to 40% has a significant reduction on the horizontal and vertical force coefficients on the cage, whereas the change is insignificant on QCPBW. The horizontal wave force is three to four times higher when compared to the vertical wave force for both QCPBW as well as on the porous cage. For a system comprising four units of cages, both the horizontal and vertical wave forces on cage 1, 2, 3, and 4 reduce progressively (cage 2 is at the lee side of cage 1 and so on). The results of the present study can be used for the optimal design of open sea porous systems.

KEYWORDS:

• Quarter-circular porous breakwater
• porous cages
• gravity waves
• wave scattering
• dual boundary element method
• nonlinear pressure drop

Nomenclature

Table

CRediT author statement

Nishad: Methodology, and Formal Analysis. Neelamani: Conceptualization, Data curation, Original draft preparation, Formal Analysis and Investigation. Vijay: Conceptualization, Methodology, Matlab Coding, Formal Analysis and Investigation. All the authors are responsible for reviewing and editing the manuscript.

Disclosure statement

We wish to confirm that there are no known conflicts of interest associated with this publication and there has been no significant financial support for this work that could have influenced its outcome.

Data availability

All data that support the findings of this study are available from the corresponding author on a reasonable request.

Correction Statement

This article has been republished with minor changes. These changes do not impact the academic content of the article.