Faculty Publications
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Item Performance evaluation of submerged breakwater using Multi-Domain Boundary Element Method(Elsevier Ltd, 2021) Patil, S.B.; Karmakar, D.The gravity wave interaction with submerged breakwater of different structural configurations are investigated based on the small-amplitude wave theory. The boundary value problem is analysed in two-dimension using the linearized wave theory in water of finite depth. The submerged breakwater structural configuration such as (i) thin-walled type (impermeable), (ii) rectangular type (impermeable and permeable), (iii) triangular type (impermeable, permeable, perforated), (iv) trapezoidal type (impermeable, permeable, perforated) and (v) Tandem type (impermeable, permeable, perforated) are considered to analyse and performance of the breakwater. The numerical model is developed using the Multi-Domain Boundary Element Method (MDBEM) to analyse the hydrodynamic scattering coefficient (such as reflection, transmission and dissipation coefficient) for the change of physical parameters such as relative spacing between the breakwaters, relative water depth and structural dimensions. The convergence of the present numerical model is performed for the specific case of tandem breakwater and numerical computation is validated with the results available in the literature. The wave reflection and transmission coefficient along with wave force on the structure is analysed for different shapes, structural parameters and geometrical parameters of the breakwater to maximize the efficiency of breakwater. In the case of permeable breakwater, the submerged tandem breakwater is found to be more efficient in wave transformation as compared to rectangular, triangular and trapezoidal permeable submerged breakwaters. The comparative analysis performed on different configurations of the breakwater in the present study will be helpful in the effective design of the breakwater near the harbour regions. © 2021 Elsevier LtdItem Hydrodynamic analysis of floating tunnel with submerged rubble mound breakwater(Elsevier Ltd, 2022) Patil, S.B.; Karmakar, D.The wave interaction with a Submerged Floating Tunnel (SFT) of two different shapes (rectangular and circular) in the presence of a submerged rubble mound breakwater (SRMB) is analyzed using Multi-Domain Boundary Element Method (MDBEM). Furthermore, three typical SFT cross-sections (rectangular, trapezoidal, and circular) of equal area and structural height in the presence of SRMB under similar operating conditions are investigated as comparative study to analyse the influence of SFT shape on hydrodynamic performance. The performance of the tunnel configurations is analyzed as a (a) measurement in terms of hydrodynamic efficiency and (b) criterion for tunnel structure safety. In both shallow and intermediate water depth regions, the critical wave number and the critical angle of incidence followed by resonant wave reflection are identified, and suitable structural parameters of SRMB such as structural porosity in the armour layer, relative crest width, relative gap width between the SFT and the SRMB, structural width and position (relative draft of tunnel structure measured from the free water surface) of SFT are investigated. The present parametric investigation of SFT with SRMB reveals an improved wave transformation properties for a specific range of water depth. The coupling of SRMB has resulted not only in a reduction of wave-induced force acting on SFTs, but also in improved performance in wave transformation characteristics as a coastal protection structure, which is substantially determined by SRMB structural properties. Due to the presence of SRMB, the SFT's safety is improved, which may also add stability to the SFT. A comparative study of different distinct cross-sections of SFTs indicates that, due to its shape, the circular SFT has a reduced reflection capability and lower wave-induced force with nearly the same wave transmission as the rectangular and trapezoidal SFT. The study performed on the coupled SFT and rubble mound breakwater may be useful in determining the suitability of breakwaters not only for maintaining shore dynamics but also for protecting important floating structures for underwater transit. © 2022 Elsevier LtdItem Dissipation of Gravity Waves Due to Submerged Porous Plate Coupled With Porous Structures(American Society of Mechanical Engineers (ASME), 2023) Krishna, K.R.A.; Abdulla, K.; Karmakar, D.The present study focuses on wave trapping due to the submerged horizontal porous plate combined with the bottom-standing porous structure and surface-piercing porous structure. The submerged plate thickness is considered to be negligible as compared to the incident wavelength and water depth, and the porous structure is considered to be of finite width. The study is performed based on the eigenfunction expansion method, and the wave interaction with the combined structure is investigated using the small amplitude wave theory. The orthogonal mode-coupling relation is used to analyze the wave interaction with the combined structure. The reflection, transmission, and dissipation coefficients along with wave force on the porous structure are investigated to analyze the hydrodynamic performance of the composite porous breakwater system. Further, the effect of porosity of submerged plate and structure, submergence depth of plate and structure, angle of incidence, and the submerged plate length are investigated to analyze the effective wave dissipation by the composite breakwater. In addition, the comparative study of the numerical method is performed with the results available in the literature. The study noted that the wave damping due to the submerged porous plate backed by surface-piercing porous structure is more as compared to the submerged porous plate backed by the bottom-standing porous structure. The study performed will be helpful to scientists and engineers in the design of suitable composite breakwater systems and also assists in selecting the best structural configuration for attenuation of wave height and to protect the offshore facility from high waves in the coastal region. © 2023 American Society of Mechanical Engineers (ASME). All rights reserved.Item Hydrodynamic Performance of Fixed Floating Structures Coupled with Submerged Breakwaters Using the Multidomain Boundary Element Method(American Society of Civil Engineers (ASCE), 2023) Patil, S.B.; Karmakar, D.The hydrodynamic characteristics of fixed floating structure (FFSs) of various configurations, such as rectangular fixed floating structures and trapezoidal fixed floating structures coupled with submerged breakwaters of two different shapes, namely, rectangular breakwater and trapezoidal breakwater, are investigated using the multidomain boundary element method under the framework of small-amplitude wave theory. The hydrodynamic analysis of the FFS with and without the presence of submerged breakwater is performed for the variation in physical parameters such as a change in structural parameters of the submerged breakwater (shape, relative submergence depth, relative crest width, and structural porosity), structural parameters of FFS (shape and structural width), wave parameter (angle of incidence), and relative spacing between the FFS and submerged breakwater. The study demonstrates, for a given range of incident wave angles, periodic values of the distance between the submerged breakwater and the FFS and optimal shape combinations for which the coupled structures act effectively in attenuating wave force acting on the FFS and optimizing wave transformations. In addition, to enhance the hydrodynamic performance, the presence of reef structures in front of the FFS is associated, which results in Bragg's resonance with a phase shift in peaks of wave reflection and transmission coefficient caused by changing the structural porosity of the submerged breakwater, indicating that the proposed models are more flexible, allowing demand-based control over shore dynamics and coastal management. The study will be useful for coastal management and safeguarding floating structures by selecting various forms and combinations of coupled FFSs with submerged porous breakwaters. © 2023 American Society of Civil Engineers.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 analysis of an H-shaped pile-restrained floating breakwater combined with a pair of vertical barriers(Elsevier Ltd, 2024) Panda, A.; Karmakar, D.; Rao, M.The present study analyses the performance of a composite breakwater consisting of an H-shaped breakwater attached with vertical/inclined barriers held from both sides using the Multi-Domain Boundary Element Method (MDBEM). The study is performed to analyse the wave transformation characteristics (reflection and transmission), wave energy dissipation and horizontal wave forces due to the gravity wave-structure interaction. The hydrodynamic performance of the integrated breakwater is performed due to the effect of changing various structural properties such as porosity, width and depth of structural elements, relative spacing between breakwater and barrier, angle of incidence and the inclination of the barriers. The boundary conditions and the corresponding edge conditions are incorporated for each surface and interface and correlated with Green's function to solve the boundary value problem. The detailed study proposes the suitable dimensions of the structural elements of the breakwater for optimal performance. The application of inclined barriers over the vertical barrier in certain conditions for maximising wave reflection is presented and analysed to understand the effectiveness of the barrier inclination. The favourable barrier dimensions and the suitable relative spacing for deep water regions are discussed, and the effect of rigidity and porosity of the barriers are analysed to maximise breakwater performance in wave attenuation. On considering the suitable design parameters and structural stability, the composition of vertical/inclined barriers with an H-shaped pile-restrained floating breakwater serves as a protective component by encountering maximum wave force and dissipating considerable wave energy to provide an efficient solution in harbour protection. © 2024 Elsevier LtdItem Oblique wave interaction with pile-restrained dual H-shaped breakwater(National Institute of Science Communication and Policy Research, 2024) Panda, A.; Karmakar, D.; Rao, M.The hydrodynamic performance of pile-restrained dual H-shaped floating breakwater is investigated using the small amplitude wave theory considering oblique wave incidence. The research on a single H-shaped floating structure supported by the piles has demonstrated effective wave reflection and wave trapping due to its distinctive configuration, composed of a vertical member called a web and a horizontal member called a flange. Thus, the dual H-shaped breakwater is proposed to enhance the breakwater’s efficiency and to provide additional support to the leeside structure. The present analysis is performed by varying the structural parameters such as the width and submergence draft of the web, flange width of the dual H-shaped breakwaters and the corresponding effect on the hydrodynamic coefficients along with the wave-induced force acting horizontally on the breakwater using Multi-Domain Boundary Element Method (MDBEM). Based on the study, the leeside structure experiences a greater wave force than the primary H-shaped structure placed seaside for the critical angle of incidence. The dual H-shaped breakwater is noted as a highly effective harbour defence solution based on the structural and design specifications. The dual H-shaped pile-restrained floating breakwaters provide protection by absorbing the highest wave force and releasing a significant quantity of wave energy. © 2024, National Institute of Science Communication and Policy Research. All rights reserved.Item Effect of seabed condition on the hydrodynamic performance of a pile-restrained H-shaped floating breakwater(Taylor and Francis Ltd., 2025) Panda, A.; Karmakar, D.; Rao, M.The present study investigates the hydrodynamic analysis of pile-restrained H-shaped porous breakwater for various seabed conditions using the small amplitude wave theory. The Multi-Domain Boundary Element Method (MDBEM) is employed to investigate the influence of parametric variations on the hydrodynamic coefficients and horizontal wave force under normal and oblique incident waves. The numerical accuracy is ensured by comparing it with the available literature. The numerical investigation on the hydrodynamic performance of the H-shaped breakwater is performed for various seabed configurations considering different angles of slope, the width of slope/step/obstacle, step height, number of steps, soil permeability, angle of wave incidence, the width of flange and submergence draft of the web of the H-shaped structure. The findings indicate that the seabed undulation has a higher wave impact on the breakwater than the horizontal seabed. In addition, the study suggests that the sloped seabed is preferable in deeper water depths to reflect waves efficiently and the seabed permeability can affect the hydrodynamic coefficients in shallow and intermediate water depths. The study performed on the H-shaped breakwater for varying seabed topography will be helpful in the design and construction of a suitable H-shaped breakwater for an effective wave absorber in coastal regions. © 2025 Informa UK Limited, trading as Taylor & Francis Group.Item Hydroelastic analysis of VLFS integrated with porous floating box breakwater using multi-domain boundary element method(Elsevier Ltd, 2025) Hemanth, S.; Karmakar, D.The present study analyses the feasibility of integrating a Very Large Floating Structure (VLFS) with a porous floating box-type breakwater kept fixed in its position to analyze the hydroelastic responses within the integrated system based on linearized wave theory. The integrated VLFS-breakwater system, comprising the VLFS and the porous box-type breakwater assures in mitigating the structural effects induced by waves. The coupled Multi-Domain Boundary Element Method (MDBEM) and Finite Difference Method (FDM) are employed to investigate the performance of integrated VLFS-breakwater system. The computational framework employs the MDBEM to model the fluid domain and the floating breakwaters, while the VLFS is modeled using the FDM approach. The study considers three distinct relative positions of the VLFS integrated with a floating breakwater on (i) the leeside, (ii) the seaside, and (iii) on both leeside and seaside of the VLFS. The numerical study is performed based on thin-plate theory and small amplitude wave theory. The study corroborates its numerical findings with existing literature, supporting the validity of its methodology. The integrated system effectively reduces forces acting on the VLFS by absorbing the primary impact of waves. Consequently, the hydroelastic response of the VLFS is reduced, preserving its structural integrity and enhancing overall safety. The study signifies the importance of integrating the porous box-type breakwater with the VLFS. The importance of the orientation of the structure towards the sea waves, the porosity of the breakwater, the effect of relative spacing between the breakwater and VLFS and variations in hydrodynamic responses with respect to the placement of the floating breakwater are thoroughly discussed. The study performed will be helpful in the design and implementation of integrated VLFS-breakwater system, enhancing their robustness and safety in maritime environments. © 2024 Elsevier LtdItem 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 Ltd