Oblique wave interaction with a two-layer pile-rock breakwater placed on elevated bottom

ABSTRACT

The two-layer pile-rock porous breakwater consisting of the upper porous layer, middle porous layer placed over the bottom rigid layer (elevated bottom) is proposed as an active wave absorber for significant wave damping and wave trapping. The two-layer rock core is placed between the two thin porous barriers (piles), and the thin barriers/ piles are useful to reduce the wave force experienced by active two-layered breakwater. The eigenfunction expansion method is used to analyse the physical problem on considering the continuity in fluid velocity and pressure along with mode-coupling relation based on classical linearised potential flow theory. The developed analytical model is validated with the available results and then various hydrodynamic characteristics such as wave reflection, transmission, damping, wave forces on seaward, leeward barriers and wave force experienced by the vertical cliff are presented. The porosity of surface layer shows an effective role in reducing the harmonic oscillatory pattern in the hydrodynamic quantities, and the study suggests the higher surface layer porosity ${\epsilon }_s=0.8$ as compared with bottom layer porosity for optimal wave damping.

KEYWORDS:

• Eigenfunction expansion method
• multi-layered structure
• wave trapping
• wave scattering
• pile-rock breakwater

SUBJECT CLASSIFICATION CODES:

• 74J15
• 74J20

Acknowledgements

VV and KA are thankful to the Department of Civil Engineering, Bapatla Engineering College, Bapatla for providing the necessary facilities. DK acknowledges the partial support from the Science and Engineering Research Board (SERB), India through research grant CRG/2018/ 004184.

Disclosure statement

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