Dissipation of incident wave energy by two floating horizontal porous plates over a trench type bottom

ABSTRACT

This work investigates the scattering of oblique incident waves by two floating horizontal porous plates over a trench-type sea bed to study the role of different pairs of barriers in dissipating the incident wave energy. This problem is modelled based on Darcy's law for flow past a porous structure. Havelock's expansions of water wave potentials, suitable matching conditions, and the algebraic least-square method handle the boundary value problem. The role of the horizontal porous plates is studied by analysing the scattering coefficients, energy loss, hydrodynamic wave force and free surface elevation through graphs which show a periodic oscillatory pattern as a function of gap length. The study reveals that if the porous effect parameter of plates or the length of plates is increased, more energy is dissipated and the plates experience less wave force, and the free surface elevation on the lee side is decreased. The present results also signify that as compared to rigid plates, significant changes are found in wave scattering coefficients, hydrodynamic force and free surface elevation due to the consideration of one porous plate along with one rigid plate and also two porous plates, where a pair of porous plates are more effective as compared to one porous plate. The present study reveals that the scattering of water waves by two floating horizontal porous plates over uneven bottom topography plays a vital role in constructing floating structures having more staying power in harsh wave environments.

KEYWORDS:

• Water wave scattering
• horizontal porous plates
• algebraic least-square method
• dissipation coefficient
• scattering coefficients
• wave force

Acknowledgments

The authors thank Dr. Harekrushna Behera, SRM Institute of Science and Technology, Tamil Nadu, India for his valuable suggestions during the revision of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

Sunita Choudhary is thankful to the University Grants Commission (UGC), Govt. of India, for fellowship [Ref. No. JUNE18-419784] for pursuing Ph.D. degree at the Indian Institute of Technology Ropar, India. This work was partially supported by the FIST program of the Dept. of Science and Technology, Govt. of India (IN) [Ref. No. SR/FST/MS-I/2018/22(C)].