Faculty Publications
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Item Wave trapping due to composite pile-rock structure coupled with vertical barrier(SAGE Publications Ltd, 2023) Sreebhadra, M.N.; Krishna, K.R.A.; Karmakar, D.The wave transformation due to pile-rock porous structure in combination with vertical porous barrier is studied under oblique wave action. The pile-rock breakwaters consists of two rows of closely spaced piles and a rock core between them is effective in dissipating wave energy when compared with traditional rigid breakwaters due to its reduced deadweight of construction materials and additional stability. Three different cases of the vertical barrier configurations such as fully-extended barrier, bottom-standing barrier and surface-piercing barrier placed in front of the pile-rock porous structure are considered for the investigation. The numerical study is performed using the eigenfunction expansion and the associated orthogonal mode-coupling relations considering the continuity of pressure and velocity for the vertical barrier, seaward and leeward structural interfaces. The Darcy’s law is incorporated for the flow through porous media and the porosity factor of the structure is introduced using the complex porous effect parameter. The numerical results for the wave reflection, transmission and dissipation coefficient, wave force on front and rear side of porous structure along with the wave force on the barrier interface are evaluated for different hydraulic characteristics. The analysis is presented for varying structural porosity, angle of incidence, structural thickness, friction factor, length between vertical barrier and porous structure for the three different cconfigurations of vertical barrier. The numerical investigation performed in the present study will be useful for the design and analysis of the composite breakwater system to protect the offshore facility from high waves. © IMechE 2022.Item Wave attenuation due to stratified porous structure in the presence of stepped seabed(Springer Nature, 2024) Varghese, A.; Krishna, K.R.A.; Karmakar, D.The wave transformation due to the stratified porous structures in the presence of stepped seabed at leeward side is analysed based on the small amplitude wave theory. The study is performed to analyse the effectiveness of both horizontal and vertical stratified porous structure for the wave attenuation in the nearshore regions using orthogonal mode-coupling relation and eigenfunction expansion method. The hydrodynamic coefficients such as wave reflection, transmission, dissipation, wave force acting and surface elevation are investigated for both horizontally and vertically stratified porous structures. The effect of change in the structural properties such as varying porosity, friction factor, structural width, angle of incidence and length between the porous structure and stepped seabed are examined. Thereafter, the comparative study is performed for both horizontally and vertically stratified porous structure in the presence of stepped seabed and the numerical results are validated with the results available in the literature. The present study illustrates that with the increase in step height, the wave damping efficiency is enhanced. In addition, the wave energy dissipation is observed more for horizontally stratified structure in the case of longer waves whereas vertically stratified structure is effective in dampening of shorter waves. Further, the wave reflection and transmission for vertically stratified structure is found to be more for same length between structure and stepped seabed. The stepped seabed in leeward side in combination with vertical and horizontal stratified porous structure is intended to be an effective solution for protection of coastal facility. © The Author(s), under exclusive licence to Sociedade Brasileira de Engenharia Naval 2024.