Trilochan Sahoo

• Ph.D(Math), IISc, Bangalore, INDIA
• Professor at Indian Institute of Technology Kharagpur

This paper investigates the interaction of water waves with multiple thin horizontal floating porous plates over multiple trenches at the bottom. The boundary value problem is solved for velocity potential using Havelock's expansion and algebraic least-square method. To understand the advantage of multiple porous plates and trenches, the numerical...

We implement porous breakwaters to mitigate the effects of wave loads on diverse marine structures and to dissipate excess wave energy, thereby establishing a tranquil zone. This paper demonstrates the effectiveness of wave scattering by a graded array of surface-piercing vertical porous barriers of different configurations, namely, (a) monotonical...

The role of a vertical flexible porous barrier of two different configurations, namely (i) surface-piercing barrier (SPB) and (ii) bottom-standing barrier (BSB) in the mitigation of hyroelastic responses of a very large floating structure (VLFS) is analysed. Both the flexible barrier and the floating plate are modelled using Euler-Bernoulli beam eq...

The study uses linearized water wave theory to examine the role of detuned frequency on Bragg scattering of surface gravity waves over an array of bottom-standing submerged sinusoidal patches. Explicit formulae for reflection and transmission coefficients are derived using the matrix transfer method in the case of an array of patches, with each pat...

A Fourier Bessel series type expansion formula is used to investigate the interaction of surface gravity wave with two arc-shaped porous breakwaters that shield a circular floating flexible structure from wave action. The flexural gravity waves result from the interaction between the surface gravity waves and the circular floating structure. Additi...

Flexural-gravity wave scattering by an array of vertical porous barriers of various configurations is investigated in finite water depth from the viewpoint of blocking dynamics. A scattering matrix is introduced for the velocity potentials using the canonical eigenfunction expansion method developed for a single propagating wave mode to account for...

This study examines the formation of triads of flexural gravity wave in a homogeneous fluid within the context of blocking dynamics due to the presence of shear current. This study will enable us to understand the distribution of wave energy on an ice-covered sea surface. New classes of triads for flexural gravity waves are introduced depending on...

The present study investigates the scattering of flexural gravity waves due to uneven bottom topography in the context of wave blocking. Emphasis is given to analyzing the effects of multiple propagating wave modes on the solution procedures. The mathematical model is developed for two scenarios: a bottom step and a submerged rectangular breakwater...

This research aims to investigate the hydrodynamic performance and efficiency of the LIMPET oscillating water column (OWC) device. A two-dimensional NWT is used in a fully nonlinear RANS model with the k-ω turbulence model for the Stokes secondorder incident waves. A VOF method is utilized to capture the free surface elevation. The simulation shows...

The present study deals with the surface gravity wave interaction of a submerged composite wavy porous plate in the presence of a tunnel placed at a finite distance under the assumption of small amplitude theory and a two-dimensional framework. To solve the boundary value problem, a numerical method using the multi-domain boundary element method (M...

Flexural-gravity wave blocking is demonstrated in a three-layer fluid having a floating ice-covered surface in the water of finite depth. The study reveals that wave blocking occurs for higher values of compressive force in either of the modes, which depends on the density ratio and the wave frequency. Two (three) roots of the dispersion relation c...

The results of a theoretical study on Benjamin–Ono (BO) soliton evolution are presented in a simple model of a two-layer ocean with a shear flow and viscosity. The upper layer is assumed to move with a constant speed relative to the lower layer with a tangential discontinuity in the flow profile. It is shown that in the long-wave approximation, suc...

Surface gravity waves interact with the flexural waves to generate the flexural gravity waves whose characteristics are triggered for higher values of lateral compressive stress to generate multiple propagating wave modes. This investigation examines the scattering of obliquely incident flexural gravity waves due to articulation in two semi-infinit...

Scattering of obliquely incident flexural gravity long waves by an articulated floating elastic plate is studied within the framework of blocking dynamics. The dispersion curve reveals that for a range of compressive force prior to buckling limit, wave blocking occurs for two different values of time-period where group velocity vanishes. Moreover,...

The study deals with the blocking of flexural gravity waves, which is developed due to the interaction of surface gravity waves with a floating submerged plate resting on a viscoelastic foundation. Here, the Winkler foundation is generalized using the Kelvin-Voigt model to account for the viscoelastic foundation. The roots of the dispersion relatio...

Surface gravity wave interaction of composite wavy porous plate is studied by developing a numerical model using the boundary element method in the context of two-dimensional linear potential theory. Bragg scattering phenomenon is studied by considering the linearized pressure drop condition known as Darcy's law passing through the porous structure...

Surface gravity wave scattering by an array of floating flexible plates having free/moored edges and resting on a Winkler foundation are studied within the framework of flexural gravity wave blocking. The impact of the floating plates having moored edges compared to that of free edges along with the occurrences of Bragg reflection are analysed. The...

This research examines the hydrodynamic performance of the oscillating water column device under the influence of irregular incident waves. The numerical model is based on the Reynolds-Averaged Navier-Stokes equations (RANS) with a modified k − ω turbulence model and uses the volume-of-fluid (VOF) approach to monitor the air-water interface. To exp...

Flexural-gravity wave scattering due to an array of polynyas is investigated from the perspective of the blocking dynamics. The canonical eigenfunction expansion method is generalized to account for multiple propagating wave modes within blocking frequencies. Bragg scattering occurs due to the presence of multiple gaps in the floating ice sheet, an...

Surface gravity wave interaction with an articulated flexible submerged plate in the presence of lateral compressive force is investigated within the framework of blocking dynamics, assuming that the submerged plate is resting on a uniform Winkler foundation. The problem is studied considering small-amplitude plate response and linearised water wav...

In the present study, the gravity wave scattering by circular edged breakwaters in the presence of retrofits is analysed within the framework of linearized water wave theory. Various types of retrofits (say, porous shield) such as quarter-circular retrofit, semi-rectangular retrofit, semi-circular retrofit, and rectangular retrofit are investigated...

A numerical investigation based on the boundary element method is conducted to analyze the effect of step bottom on the radiation of surface gravity wave by the rectangular marine structure under the assumption of a two-dimensional linearized water wave theory. The investigation is supplemented by analyzing the presence of a back wall located near...

The present study deals with the formation of triads in flexural gravity waves in a two-layer density stratified fluid having a flexible plate-covered surface and an interface within the framework of blocking, which can be used as a mechanism for understanding the spectral distribution of wave energy. The physical model is considered in a two-dimen...

Bragg scattering of surface gravity waves by an array of submerged bottom-standing non-smooth breakwaters is studied under the assumption of linearized long wave theory. The closed-form long-wave analytical solutions are derived and validated by comparing them with the results available in the literature. The role of various physical parameters suc...

We investigate the effectiveness of a porous box in attenuating the structural response of a very large floating structure (VLFS). Assuming the water depth to be finite and small amplitude water wave theory, the physical problem is formulated by employing Darcy's law for flow past a porous structure. The boundary value problem is reduced to a syste...

The scattering of gravity waves by vertically staggered multiple porous barriers having variable porosity is analyzed within the framework of linearized water wave theory in two dimensions. The barriers are assumed to follow quadratic pressure boundary conditions to account for energy dissipation with the changes in the wave height, which is often...

Scattering of obliquely incident surface gravity wave by a semi-infinite floating elastic plate in the presence of lateral compressive force is studied within the framework of blocking dynamics in time-space. In the presence of lateral compressive force, primary and secondary wave blocking occur for two different values of time-period where the gro...

The influence of wave blocking on the scattering of a flexural-gravity wave by a linear crack in a thin ice cover resting over a two-layer ocean having a rigid flat seafloor is investigated. The wave dispersion curve reveals the existence of multiple propagating wave modes within the blocking frequencies, either in the surface or interface mode. Th...

Scattering of flexural gravity waves due to an abrupt change in structural heterogeneity is studied within the framework of blocking dynamics in time-space under shallow water approximations. As a special case, wave scattering due to a crack in the ice sheet is obtained. In the presence of compressive force, primary and secondary wave blocking occu...

In the present study, capillary-gravity wave blocking in a two-layer fluid in the presence of surface and interfacial tensions are analyzed under the assumption of the linearized theory of water waves. In the presence of surface and interfacial tensions, two propagating capillary-gravity wave modes exist, namely barotropic (surface) and baroclinic...

The scattering of surface gravity waves by a skirt wall breakwater is analysed in two dimensions under the assumption of small-amplitude wave theory. The oscillatory wave past the porous skirt walls is assumed to follow Darcy's law. The boundary value problem is solved using multi-domain boundary element method to obtain the numerical results for t...

The hydrodynamic performance of composite wavy submerged porous plate attached to a wall is investigated using numerical method MDBEM (Multi-domain boundary element method) in the linearized water wave theory in which wave past the porous barriers are modelled using Darcy law. Effect of the presence of wall on the hydrodynamic parameters like refle...

An interesting physical phenomenon was recently observed when a fresh-water basin is covered by a thin ice film that has properties similar to the property of a rubber membrane. Surface waves can be generated under the action of wind on the air–water interface that contains an ice film. The modulation property of hydro-elastic waves (HEWs) in deep...

Bragg scattering of long flexural gravity waves due to an array of submerged trenches is studied under the shallow water approximation and small amplitude structural response in the presence of lateral compressive force. The group velocity vanishes at two different points in the frequency space for specific values of the compressive force, which ar...

Linear surface gravity wave scattering by a partial porous breakwater is studied in a two-layer ocean having an interface with bottom undulations. The partial breakwaters, namely surface-piercing breakwater (SPB) and bottom-standing breakwater (BSB), are considered. The continuity of fluid pressure and mass flux is applied at interface boundaries,...

Surface gravity wave interaction with a semi-infinite floating elastic plate in the presence of multiple undulations has been studied under the assumption of linearized water wave theory and small amplitude structural response. The elastic plate is modeled using the Euler-Bernoulli beam equation, whilst the multiple undulations are categorized as a...

The scattering of gravity waves by a rigid floating dock in the presence of an array of porous and non-porous breakwaters of different configurations is analysed under the framework of linear potential flow theory. The waves passing the submerged porous structures are assumed to follow Darcy’s law. Two independent physical problems such as the arra...

The present study investigates the influence of nonlinear waves on the oscillatory pore pressure-induced response around buried pipes. The study is carried out considering the applicable wave theories namely: linear, Stokes, cnoidal and solitary wave theories. The soil modelling is based on Biot’s consolidation equations which are solved using Fini...

The time-dependent motion of flexural waves generated by the vibration of an elastic plate resting on a variable Winkler foundation with compression is studied. The physical problem is analysed under the assumption of small amplitude structural response in two dimensions. The dispersion equation is analysed in detail, and points of wave blocking a...

Wave climate over the North Indian Ocean region experienced a paradigm shift in the recent past, indicating an increase in the extremes. Wind-waves and swell climatology have shown an increasing trend over this region, having direct implications on the coastal zone dynamics surrounding the mainland and island features. The present study aims to inv...

In the present study, the influence of bed slope on the hydrodynamic performance of a floating oscillating water column (OWC) device is investigated. Numerical computations are performed using the incompressible multiphase volume of fluid (VOF) approach. A dynamic meshing technique is adapted to capture the body motions for different wave condition...

Oscillating water column (OWC) wave energy converters are one of the most widely researched devices for ocean wave energy harvesting. This study investigates the hydrodynamic performance of a shore-fixed OWC device for different bottom slopes using two numerical approaches, namely, computational fluid dynamics (CFD) and boundary integral equation m...

n the present study, the effectiveness of using multiple slatted screens placed in front of a caisson porous breakwaterto dissipate the incident wave energy is analyzed. To model the water flow through the slatted screens, a quadratic(nonlinear) pressure drop condition, which involves both the inertial and drag effects is considered. Further, for t...

A hydroelastic model is developed to study the interaction of linear long gravity waves with a very large floating flexible plate resting on a viscoelastic foundation, which is based on the Kelvin–Voigt model. Flexural gravity wave blocking occurs for specific values of the compressive force in the absence of viscous damping. During wave blocking,...

In the present study, gravity wave interaction with a series of submerged artificial permeable reefs is analysed within the framework of linearised water wave theory. For wave past porous walls of the artificial reefs, a quadratic pressure drop is assumed to account for the wave energy dissipation due to the changes in wave height. The physical pro...

The modulation instability of surface capillary-gravity water waves is analysed in a shear flow model with a tangential discontinuity of velocity. It is assumed that air blows along the surface of the water with a uniform profile in the vertical direction. Such a model, despite its simplicity, plays an important role in hydrodynamics as the referen...

In this article, a coupled model is proposed for wave interaction with a pair of submerged floating tunnels in the presence of an array of bottom-standing trapezoidal porous breakwaters. The theory of Sollitt and Cross is adopted to govern the fluid flow inside the porous medium. For constant water-depth, the eigenfunction expansion method is emplo...

The modulation instability of surface capillary-gravity water waves is analysed in a shear flow model with a tangential discontinuity of velocity. It is assumed that air blows along the surface of the water with a uniform profile in the vertical direction. Such a model, despite its simplicity, plays an important role in hydrodynamics as the referen...

This study examines the multiple layers in a rubble mound breakwater and their effect on reflection and dissipation of incoming ocean waves. The numerical model is developed using multi-domain boundary element method for oblique water wave trapping near a sloping wall by a multi-layered trapezoidal porous structure, which is utilized to model armou...

Bragg scattering of surface gravity waves by a slender pile-supported submerged wavy porous plate is studied under the assumption of small amplitude water wave theory. The waves past porous barriers are modeled using linearized pressure drop boundary condition known as Darcy law. Numerical solution for the boundary value problem is obtained using t...

The gravity wave interaction with horizontally staggered multiple thin wavy porous barriers is analyzed under the assumption of potential flow theory. The dual boundary element method (DBEM) is used to solve the boundary value problem. The accuracy and reliability of the DBEM solutions are ascertained by comparing with known results in the literatu...

Scattering of obliquely incident surface gravity waves by an array of partial flexible vertical porous wave barriers ofvaried configurations is studied in finite water depth and deep water cases. For the mathematical modeling purpose,linearized water wave theory is considered. Firstly, the problem associated with double vertical barriers is handled...

Bragg scattering of long gravity waves by an array of floating elastic plates in the presence of a series of rectangular trenches is studied under the assumption of linearized water wave theory and small amplitude structural response. Bragg reflection occurs in the case of an array of multiple floating flexible plates and trenches in isolation or c...

The problem of scattering for flexural-gravity waves has been the subject of extensive research motivated by understanding the wave processes which are prominent in the ice-infested ocean and the engineering challenges associated with very large floating structures. Many different problems in wave scattering have been solved, and the field has reac...

A numerical model based on multi-domain boundary element method (BEM) is developed to study the gravity wave interaction with a horizontally submerged wavy porous plate. The boundary condition on the porous barrier is considered a quadratic pressure drop to incorporate the effect of wave height on the wave energy dissipation directly. The performan...

The interaction between oblique water waves and floating bridge in the presence of a vertical partial flexible permeable barrier is studied under the assumption of the linear water wave theory in finite water depth. The associated mathematical problem is handled for a solution using the least-square approximation method. The reflection and transmis...

In the present study, gravity wave interaction with a wave attenuating system (WAS) comprised of a series of surface piercing thin vertical porous plates fixed on a fully submerged rigid pontoon is analyzed. For the wave past porous barriers, a quadratic pressure drop is considered to account for the energy dissipation due to changes in wave steepn...

The propagation of flexural-gravity waves in a coupled submerged and floating plate system is studied, and the complex flexural gravity wave propagation properties are investigated in the frequency and time domain, The system exhibits two modes of propagation analogous to the surface and internal waves in a two-layer fluid. The effect of the plate...

A coupled model of wave interaction with a submerged floating sea-tunnel in the presence of a bottom mounted submerged porous breakwater is proposed to study the role of porous breakwater in mitigating wave effects on tunnel. In this study, three configurations of the porous breakwater namely trapezoidal, circular and wedge shapes are analyzed. The...

A multi-domain boundary element code is developed to study the effect of permeable plates for attenuating wave-induced response of a floating structure near a rigid wall. The physical problem is studied in two-dimensions under the assumptions of linearized water wave theory in water of finite depth. It is observed that in the presence of permeable...

In the present study, the occurrence of Bragg resonance has been demonstrated due to scattering of long gravity waves by an array of submerged trenches in the presence of the sloping sea bed. The closed-form long wave analytical solutions are derived using the solutions of Bessel equations and validated with numerical results obtained via the bound...

Oblique gravity wave interaction with a thick porous breakwater is analyzed in a two-layer ocean having bottom undulation. The plane-wave solution in water of constant depth is matched with the solution of mild-slope equation in the region of varying depth. The breakwater is assumed to be extended from free-surface to seabed. Two different physical...

We investigate the scattering of obliquely incident water waves by a surface-piercing porous box in finite depth of fluid. The physical problem is modelled based on the small amplitude water wave theory and Darcy’s law for flow past a porous structure. Using the matched eigenfunction expansion method, the boundary value problem is reduced to a syst...

Effective design of ports, harbours, and marinas is a major challenge due to the utilization of available space, material involvement, and capital investment. One of the major aspects of the design is the construction of cost-effective breakwater for the creation of a tranquillity zone and an increase in the usable area within the harbour. In the p...

In the present study, hydroelastic response mitigation of a very large floating circular structure by an annular flexible permeable membrane is studied under the assumption of the linearized theory of water waves and small amplitude structural response. The very large floating structure is modeled based on small amplitude plate theory, while the fl...

A numerical model is developed using the boundary element method to analyze gravity wave transformation by a finite floating dock in the presence of bottom undulation such as trenches, breakwaters and a combination of both in two dimensions. The role of bottom undulation on the sea side of the floating dock has a significant role in wave scattering...

In this study, the effect of the stepped sea bed on the hydrodynamic performance of an oscillating water column device is investigated using computational fluid dynamics . This investigation is performed in a numerical wave tank modeled using ANSYS Fluent, which incorporates a transient, multiphase volume of fluid method to track the air–water inte...

Subsea pipelines operating under high pressures and temperatures are typically buried to protect from the environmental impacts and to prevent the instigation of global buckling. As the seabed profile is generally uneven, certain initial imperfections generally exist along the pipeline. As the pipe traverses in shallow waters, the seabed can be sub...

A model for oblique wave interaction with a floating bridge in the presence of a submerged breakwater and a trench is developed. The breakwaters and trenches are considered to be of trapezoidal and circular types. The performance of these undulations in bottom bed are analyzed in detail for reflecting waves and reducing resulting forces on bridge....

The effectiveness of a floating porous plate for mitigating the wave-induced structural response of a very large floating structure is investigated using the eigenfunction expansion method. The analysis is based on the assumption of a small-amplitude structural response of the very large floating structure and the linearized theory of water waves w...

A numerical model is developed based on multidomain boundary element method (MBEM) to investigate the scattering of surface gravity waves by a pair of floating porous boxes. This study reveals that there is a significant reduction in wave forces acting on the boxes with the introduction of structural porosity. Moderate porosity is highly effective...

The study demonstrates the propagation of flexural gravity waves in the case of submerged and floating plate system. It is the continuation of the previous works by \cite{Das2018a,Das2018b,Das2018c,meylan2009water}. The dominant roles of the submerged and floating plates completely depend on the plate position, structural rigidity and compressive f...

The present study focuses on the buckling of pipelines in shallow waters subjected to surface gravity waves. The wave-induced uplift forces on pipelines buried in sandy seabeds are investigated using Biot's consolidation model. Thereafter, buckling analyses are performed on the pipeline with the combined temperature and the wave-induced loads. The...

Scattering of oblique flexural-gravity waves by a submerged porous plate in a finite water depth is investigated under the assumptions of linearized surface waves and small-amplitude structural response. The study is carried out using eigenfunction expansions and the corresponding orthogonal mode-coupling relations associated with flexural-gravity...

Flexural-gravity wave characteristics are analysed, in the presence of a compressive force and a two-layer fluid, under the assumption of linearized water wave theory and small amplitude structural response. The occurrence of blocking for flexural-gravity waves is demonstrated in both the surface and internal modes. Within the threshold of the bloc...

Flexural-gravity wave propagation under the action of a compressive force and in the presence of flow vorticity is studied under the framework of linear water wave theory. The occurrences of wave blocking which is analogous to the free surface gravity wave propagation against an opposing current as well as light wave propagation in curved space-tim...

In the present manuscript, the hydroelastic response of a flexible porous plate, floating in water of finite as well as in infinite depths, is studied under the assumption of linearized wave-structure interaction theory. Using Green's integral theorem, the associated boundary value problems are converted into integro-differential equations in terms...

A numerical model based on boundary element method is developed to study the scattering of surface gravity waves over a pair of trenches of varied configurations under the assumption of small amplitude water wave theory. Both the cases of symmetric and asymmetric trenches are considered in the present study. The accuracy of the numerical results is...

The effectiveness of partial vertical permeable barriers of three different configurations located at a finite distance from a very large floating structure is analyzed for mitigating the wave-induced response of the structure The eigenfunction expansion method is employed to obtain solution in case of normal incidence and the study is extended to...

An analytical study for surface gravity wave interaction with submerged flexible porous plate based on small amplitude water wave theory and structural response is presented. The flexible porous plate is modeled based on the thin elastic plate theory and wave past porous plate is using generalized Darcy's law to incorporate both frictional force an...

An analytical study is presented in this paper for oblique wave scattering by a floating elastic plate in a one or two-layer body of water over a porous seabed of infinite depth. The solution procedure adopted, under the assumption of small-amplitude surface waves and structural response, is the eigenfunction expansion method. The study aims to loo...

Interactions between surface gravity wave and submerged horizontal flexible structures are studied under the assumption of small amplitude water wave theory and structural response. The generalized dispersion relation associated with surface gravity wave interaction with submerged horizontal flexible plate is analyzed to understand the characterist...

An investigation has been carried out based on multi-domain boundary element method to analyze the mitigation of wave-induced hydrodynamic loads on a pair of floating rectangular bridges by retrofitting the structures with external porous plates. The study is based on the assumptions of small amplitude water wave theory in finite water depth with t...