Browsing by Author "Athul Krishna, K.R."

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    Wave Attenuation due to Stratified Porous Structure with Stepped Seabed
    (Editorial Board of Journal of Harbin Engineering, 2024) Varghese, A.; Athul Krishna, K.R.; Karmakar, D.
    The wave interaction with stratified porous structure combined with a surface-piercing porous block in a stepped seabed is analysed based on the small amplitude wave theory. The study is performed to analyse the effectiveness of partial porous structure in increasing the wave attenuation in the nearshore regions consisting of stratified porous structures of different configurations using the eigenfunction expansion method and orthogonal mode-coupling relation. The hydrodynamic characteristics such as wave reflection coefficient, transmission coefficient, dissipation coefficient, wave force impact and surface elevation are investigated due to the presence of both horizontally and vertically stratified porous structures. The effect of varying porosity, structural width, angle of incidence, wavelength and length between the porous block and stratified structure is examined. The numerical results are validated with the results available in the literature. The present study illustrates that the presence of the stratified structure decreases wave transmission and efficient wave attenuation can also be easily achieved. The wave force acting on stratified structure can be decreased if the structure is combined with wider surface-piercing porous blocks. Further, the presence of stratified porous structure combined with porous block helps in creating a tranquil zone in the leeside of the structure. The combination of vertical and horizontal stratified porous structure with surface-piercing porous block is intended to be an effective solution for the protection of coastal facilities. © Harbin Engineering University and Springer-Verlag GmbH Germany, part of Springer Nature 2024.
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    Wave Energy Damping due to Coupled Porous Structure and Submerged Porous Plate
    (Editorial Board of Journal of Harbin Engineering, 2023) Athul Krishna, K.R.; Abdulla, K.; Karmakar, D.
    The present study investigates the wave-damping characteristics due to the combination of bottom-standing porous structure, submerged porous plate, and fully-extended porous structure of finite width using the small amplitude wave theory. The hydrodynamic characteristics such as reflection, transmission, and dissipation coefficients are determined to analyse the wave energy dissipation by the composite breakwater using the matched eigenfunction expansion method and orthogonal mode-coupling relation. Darcy’s law is incorporated to the flow through porous media. The composite breakwater system is investigated experimentally to validate and compare the numerical results with the physical model study. The complex porous effect parameter for the submerged plate is incorporated in the numerical analysis, which represents the reactance and resistance of the porous structure. The wave forces on the submerged plate and porous structure for the composite breakwater are investigated by considering the effects of changing parameters such as structural porosity, plate submergence, angle of incidence, width of the submerged porous structure and distance between the structures. The study illustrates that the increasing width of the fully-extended porous structure improves the performance of the breakwater system. The proposed study on the composite breakwater yields an useful information for wave energy attenuation, which can be designed and implemented in coastal and harbour areas to achieve wave tranquillity. © 2023, Harbin Engineering University and Springer-Verlag GmbH Germany, part of Springer Nature.