Faculty Publications
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Item Hydrodynamic performance of wave energy converter integrated with pile restrained floating structure near a partially reflecting seawall(Elsevier Ltd, 2023) Patil, S.B.; Karmakar, D.The integration of a Wave Energy Converter (WEC) with a Pile-Restrained Rectangular Floating Breakwater (PRFB) in the presence of a partially reflecting vertical seawall is analysed to enhance the hydrodynamic performance and WEC efficiency of the integrated breakwater-WEC device based on small amplitude wave theory using the Boundary Element Method (BEM). The rectangular floating breakwater is designed to have heave motion with a pile-restrained floating structure placed in a position to attenuate the incoming wave in the transmitted region and the linear power take-off (PTO) damping is employed to calculate the absorbed power. The study is performed to understand the effectiveness of wave energy conversion and its hydrodynamic performance due to changes in the seawall's porosity, relative structural width, relative structural draft, wave energy conversion power take-off damping coefficients, and the relative gap of the WEC integrated with PRFB from the seawall. The study demonstrated that in the presence of a fully reflecting seawall, the wave energy extraction is enhanced for the integrated WEC system without compromising the defined threshold wave reflection coefficient but at the expense of a constrained range of wavenumbers that correspond near the system's fundamental natural frequency. Moreover, the capture width ratio is noted to be higher for relatively smaller structural drafts, while the wave reflection coefficient shows precisely the reverse trend. However, under such circumstances, the integrated WEC system operates as a motion-trapping structure, especially when the reflection coefficient of the seawall, CR≥0.75. Thus, the present study will assist the designer in determining the appropriate degrees of efficiency of the WEC device without sacrificing hydrodynamic performance by fine-tuning the hybrid floating breakwater system's geometrical parameters. © 2023 Elsevier LtdItem Hydrodynamic performance of pile restrained U-shaped OWC device using boundary element method(Elsevier Ltd, 2024) Muduli, R.; Patil, S.B.; Karmakar, D.The hydrodynamic performance of a pile-restrained U-shaped Oscillating Water Column (U-OWC) device under the action of normal incident waves is analysed using the Boundary Element Method (BEM). The hydrodynamic parameters, such as the radiation susceptance and conductance coefficients and hydrodynamic efficiency, are analysed for various cases of different structural parameters of U-OWC. It is observed that the theoretical maximum efficiency can be achieved for a wide range of wavenumbers by appropriate tweaking and optimisation of the device geometry. The resonance enables the device to reach the maximum possible efficiency and the phenomenon of obtaining the maximum efficiency of the final optimised geometry is achieved. The shorter length of draft of the device is chosen over longer draft considering the high construction cost as well as efficiency enhancement of the device, even though the longer draft is observed to perform marginally better in a narrow wave number range. The numerical investigation of the theoretical maximum efficiency is observed to be 100% whenever the μ (dimensionless radiation susceptance coefficient) crosses the zero mark. Consequently, the maximum theoretical efficiency is observed close to maximum whenever μ is close to zero. The final optimised geometry consisting of an inward inclined top wall configuration performs best but could be challenging in actual construction. Further, on inclining the bottom wall in the inwards or outward direction does not result in better performance than inclining only the top wall. The present study explores a novel concept of pile-restrained U-OWC kept near the surface and will be helpful in determining the best-performing geometry for the device. © 2023 Elsevier LtdItem Hydrodynamic performance of an oscillating water column WEC integrated with a pile-restrained H-type breakwater(Taylor and Francis Ltd., 2025) Vishwakarma, R.D.; Muduli, R.; Karmakar, D.The present study examines the hydrodynamic performance of an oscillating water column (OWC) wave energy converter (WEC) integrated into a pile restrained H-type breakwater. A three-dimensional model study is performed using ANSYS-AQWA based on potential flow theory. The results for the incident wave excitation force, shear force, and bending moment on the pile restrained breakwater and the transmission coefficient are obtained for the regular waves. The effect of incident wave angle on the forces is assessed along with the impact of changes in relative draft and width of the device. The power capture efficiency as well as wave transformation characteristics of the device are evaluated using Boundary Element Method (BEM). The study performed will be helpful to scientists and researchers to design and develop an integrated hybrid breakwater system that can protect the coast and provide useful energy by minimising the impact on the marine ecological system and environment. © 2025 Informa UK Limited, trading as Taylor & Francis Group.Item Hydrodynamic analysis of arrays of integrated U-shaped OWC device and ?-breakwater(Elsevier Ltd, 2025) Muduli, R.; Karmakar, D.The hydrodynamic performance of arrays of hybrid floating breakwater consisting of pile-restrained U-shaped Oscillating Water Column (U-OWC) integrated with ?-breakwater is analysed using Boundary Element Method (BEM). The study is performed to analyse the theoretical maximum efficiency, reflection and transmission coefficients and horizontal wave force coefficient on the top wall of the U-OWC integrated with breakwater as a function of the incidence angle as well as the non-dimensional spacing between the devices. The geometrical variations of the U-OWC relative chamber width and draft are considered to study the effect on the hydrodynamic performance. The study reveals that on increasing the relative draft of the U-OWC, the energy conversion efficiency is improved whereas the increase in the relative chamber width beyond 0.5 times the water depth (A2/h=0.5) was detrimental to the efficiency. Further, the wave reflection coefficient as a function of incidence angle is noted to be unaffected by geometric variations of the U-OWC. The wave force coefficients as a function of the non-dimensional spacing is observed to exhibit a sinusoidal pattern for the wave interaction with array of integrated U-OWC with breakwater. The numerical investigation on the array of integrated devices will enhance the knowledge and determine the performance of the array of integrated device. © 2025 Elsevier LtdItem Hydrodynamic performance of a hybrid floating breakwater-wave energy conversion system(SAGE Publications Ltd, 2025) Patil, S.B.; Karmakar, D.The study presents the hydrodynamic performance and wave energy conversion of a hybrid floating breakwater under the framework of small amplitude linear wave theory. The hybrid floating breakwater is composed of a partially liquid-filled rectangular-box type tank with built-in buoys connected to a Power Take-Off (PTO) (linear inductance generator) and is excited under regular wave conditions for (a) constrained roll motion, and (b) constrained surge, heave, and roll motion. The Boundary Element Method (BEM) is employed with the assumption of modest sloshing in the tank of the hybrid floating breakwater to estimate the hydrodynamic efficiency of the hybrid floating breakwater. Further, the experimental investigation on the Wave Energy Converter (WEC) capabilities and the hydrodynamic coefficients (wave reflection and transmission coefficients) are estimated for the excitation frequencies corresponding to nondimensional wavenumber. The present study reveals that the hybrid concept improves wave attenuation performance by 20%–35% compared to conventional floating breakwaters by increasing wave attenuation, damping and stabilizing the wave transmission coefficient (Formula presented) within (Formula presented). The experimental investigation shows that hybrid floating breakwater attaints its floating stability for the depth 15 – 25% of partially filled fluid for which the proposed design as floating breakwater as well as WEC system is achieved for a wide range of excitation frequencies. Furthermore, the hybrid floating breakwater functions as a barrier which is noted to be capable of significantly attenuating incoming progressive waves below the predetermined threshold values of wave attenuation characteristics, in addition to converting wave energy. © IMechE 2025. This article is distributed under the terms of the Creative Commons Attribution 4.0 License (https://creativecommons.org/licenses/by/4.0/) which permits any use, reproduction and distribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access page (https://us.sagepub.com/en-us/nam/open-access-at-sage).Item Hydrodynamic analysis of U-shaped OWC with varying bottom profiles integrated with ?-breakwater(SAGE Publications Ltd, 2025) Muduli, R.; Karmakar, D.In the present study, the fixed U-OWC integrated with ?-shaped breakwater is analysed considering three different bottom profiles (straight, inclined, and curved) of the interior chamber of the U-OWC. The hydrodynamic performance is assessed based on the theoretical maximum efficiency, radiation susceptance and conductance, reflection, transmission and dissipation coefficients and force coefficient on the top lip wall of U-OWC and front face of breakwater. The influence of geometric variations such as width of U-channel, draft of U-OWC, draft and width of breakwater and distance between the two structures on the hydrodynamic performance is analysed using Boundary Element Method (BEM). The study depicts that the presence of a wider U-channel width impairs the energy conversion efficiency of the U-OWC and increasing the draft of the U-OWC improves the efficiency of the device. Further, changing the bottom profile of the internal chamber of U-OWC changes the natural frequency of the device without hampering the efficiency. In addition, as the distance between the two structures is increased, transmission of waves decreases. The influence of wave force on the breakwater is noted to be maximum when the leading U-OWC structure has a curved bottom. The study on the variation of the bottom profile of the fixed U-OWC integrated with breakwater will be helpful in the design and analysis of efficient hybrid floating breakwater system. © IMechE 2024. This article is distributed under the terms of the Creative Commons Attribution 4.0 License (https://creativecommons.org/licenses/by/4.0/) which permits any use, reproduction and distribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access page (https://us.sagepub.com/en-us/nam/open-access-at-sage).