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Journal ArticleDOI

Oblique wave scattering by horizontal floating flexible porous membrane

01 Jan 2017-Meccanica (Springer Netherlands)-Vol. 52, Iss: 1, pp 125-138
TL;DR: In this article, the oblique wave scattering by a floating flexible porous membrane under the assumptions of small amplitude water wave theory and membrane response in both the cases of finite and infinite water depths.
Abstract: The present study deals with the oblique wave scattering by a floating flexible porous membrane under the assumptions of small amplitude water wave theory and membrane response in both the cases of finite and infinite water depths. Using the Green’s function technique, the boundary value problems are converted into pairs of Fredholm integral equations in terms of the velocity potentials and their normal derivatives along the membrane. Using Simpson’s quadrature formula, various integrals are evaluated and the system of integral equations are reduced to a system of linear algebraic equations which are solved to find various physical quantities of interests. Energy balance relations are derived and used to check the accuracy of the computational results. Several results of physical interests are computed and analyzed to study the effects of various wave and structural parameters. The present study will be of immense importance in creating tranquility zone for protecting coastal infrastructures through the use of floating flexible porous membrane. The concept and methodology can be used to deal with wave-structure interaction problems in related branches of mathematical physics and engineering.
Citations
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Journal ArticleDOI
TL;DR: A literature review on the research and developments of floating breakwaters is presented in this paper, where the authors classify breakwaters into seven main types, namely, the box-type, the pontoon type, the frame-type and the horizontal plate type.

126 citations

Journal ArticleDOI
TL;DR: In this article, a coupled eigenfunction expansion-boundary element method is developed and used to analyze the interaction of surface gravity waves with a submerged semicircular porous breakwater placed on a porous seabed in water of finite depth.
Abstract: In the present study, a coupled eigenfunction expansion-boundary element method is developed and used to analyze the interaction of surface gravity waves with a submerged semicircular porous breakwater placed on a porous seabed in water of finite depth. Two separate cases: (a) wave scattering by the semicircular breakwater, and (b) wave trapping by the semicircular breakwater placed near a porous sloping seawall are studied. Further, as a special case, wave trapping by a semicircular breakwater placed on a rubble mound foundation near a sloping seawall is analyzed in water of uniform depth having an impermeable bed. The wave motion through the semicircular permeable arc of the breakwater is modeled using the Darcy's law of fine pore theory, whilst the wave motion through the porous seabed, rubble mound foundation and the porous seawall are modeled using the Sollitt and Cross model. The friction coefficient defined in Sollitt and Cross model is computed by approximating the spatial dependency of the seepage velocity with the average velocity within the porous media. An algorithm for determining the friction coefficient f is provided. Various physical quantities of interests are plotted and analyzed for various values of waves and structural parameters.

54 citations

Journal ArticleDOI
TL;DR: In this paper, a literature review is presented on the theoretical, numerical, and experimental progress made in the application of porous membranes and net-type structures to breakwaters and fish cages.

40 citations

Journal ArticleDOI
TL;DR: In this article, the role of structural flexibility and porosity, wave period and angle of incidence on wave scattering by a floating flexible porous plate is investigated in water of finite and infinite depths under the assumption of small amplitude water wave theory and structural response.
Abstract: Oblique surface gravity wave scattering by a floating flexible porous plate is investigated in water of finite and infinite depths under the assumption of small amplitude water wave theory and structural response. Using the Greens function technique, the boundary value problems are converted into a system of Fredholm type integral equations in terms of the velocity potentials and their normal derivatives along the plates which are handled for solutions using Simpsons quadrature formula. Energy relations are derived to check the accuracy of the computed results. Various results of physical interests are computed and analyzed to study the roles of structural flexibility and porosity, wave period and angle of incidence on wave scattering by the plate. Certain results are analyzed to study the effect of edge conditions on the scattering of surface waves by the flexible porous plate. It is observed that depending on the heading angle of the incident waves, with suitable positioning of the plate, tranquility zone can be created by a flexible floating plate. Moreover, the study reveals that a major part of the wave energy can be dissipated with the introduction of structural porosity which will be of immense help in the creation of a tranquility zone for the protection of various marine facilities and infrastructures.

27 citations

Journal ArticleDOI
TL;DR: In this paper, the performance of bottom-standing, surface-piercing and fully extended membrane wave barriers is analyzed for various values of wave and structural parameters, and the analytic solution of the physical problem is obtained using eigenfunction expansion method and a coupled boundary element-finite difference method is used to get the numerical solution.

25 citations


Cites methods from "Oblique wave scattering by horizont..."

  • ...Recently, using the same approach as use d in [9], [11] analyzed the hydroelastic response of a floating horizontal flexible porous membrane....

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References
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Journal ArticleDOI
TL;DR: In this article, Squire et al. distinguish between two major seaice types: continuous ice, such as is normally found in the central Arctic, and the ice of marginal neighbourhoods, i.e. near the open sea, where individual ice floes and cakes are present at typically lower levels of concentration.

439 citations

Journal ArticleDOI
TL;DR: In this article, the authors derived a relation for the fluid motion through thin porous structures in addition to the conventional governing equation and boundary conditions for small-amplitude waves in ideal fluids.
Abstract: Diffraction of water waves by porous breakwaters is studied based on the linear potential wave theory. The formulation of the problem includes a newly derived relation for the fluid motion through thin porous structures in addition to the conventional governing equation and boundary conditions for small-amplitude waves in ideal fluids. The porous boundary condition, indirectly verified by collected experimental data, is obtained by assuming that the flow within the porous medium is governed by a convection-neglected and porous-effect-modeled Euler equation. A vertically two-dimensional problem with long-crested waves propagating in the normal direction of an infinite porous wall is first solved and the solution is compared with available experimental data. The wave diffraction by a semiinfinite porous wall is then studied by the boundary-layer method, in which the outer approximation is formulated by virtue of the reduced two-dimensional solution. It is demonstrated that neglect of the inertial effect of the porous medium leads to an overestimate of the functional performance of a porous breakwater.

280 citations

Journal ArticleDOI
TL;DR: In this paper, the interaction of oblique monochromatic incident waves with horizontal/inclined/dual porous plates is investigated in the context of two-dimensional linear potential theory and Darcy's law.
Abstract: The interaction of oblique monochromatic incident waves with horizontal/inclined/dual porous plates is investigated in the context of two-dimensional linear potential theory and Darcy's law (the normal velocity of fluid passing through a thin porous plate is linearly proportional to the pressure difference across it). The developed theory is verified by both small-scale and full-scale experiments. First, matched eigenfunction expansion (MEE) solutions for a horizontal porous plate are obtained. The relationship between the plate porosity and the porous parameter is obtained from systematic model tests by using six porous plates with different sizes and spacing of circular holes. Secondly, a multi-domain boundary-element method (BEM) using simple-sources (second-kind modified Bessel function) is developed to confirm the MEE solutions and to apply to more general cases including inclined or multiple porous plates. The BEM-based inner solutions are matched to the eigenfunction-based outer solutions to satisfy the outgoing radiation condition in the far field. Both analytical and BEM solutions with the developed empirical porous parameter agree with each other and correlate well with both small-scale data from a two-dimensional wave-tank test and full-scale measurement in a large wave basin. Using the developed predictive tools, wave-absorption efficiency is assessed for various combinations of porosity, water depth, submergence depth, wave heading, and plate/wave characteristics. In particular, it is found that the performance can be improved by imposing the proper inclination angle near the free surface. The optimal porosity is near porosity P=0.1 and the optimal inclination angle is around 10° as long as the plate length is greater than 20% of the wavelength. Based on the selected optimal parameters (porosity=0.1 and inclination angle=11.3°), the effective wave-absorption system for MOERI's square basin is designed.

136 citations

Journal ArticleDOI
TL;DR: In this article, a multidomain boundary element method is developed for a porous membrane based on Darcy's fine-pore model, and the inner solution uses a discrete membrane dynamic model and simple-source distribution over the entire fluid boundaries.
Abstract: The interaction of monochromatic incident waves with a horizontal porous flexible membrane is investigated in the context of a 2D linear hydroelastic theory. First, a multidomain boundary element method is developed for a porous membrane based on Darcy’s fine-pore model. The inner solution uses a discrete membrane dynamic model and simple-source distribution over the entire fluid boundaries. The outer solution is based on an eigenfunction expansion method. The inner solution is then matched to the outer solution at the matching boundaries. Second, the corresponding analytic diffraction and radiation solutions are obtained based on the multidomain eigenfunction expansion method to better understand the relevant physics and confirm the boundary element method results. Using the developed computer program, the wave-blocking performance of a submerged horizontal porous membrane is tested with various system parameters, membrane porosity, and wave characteristics. The wave numbers above the porous membrane are generally complex, and the imaginary parts contribute to the dissipation of wave energy. Therefore, the overall performance of the horizontal flexible membrane can be further enhanced by using proper porous material. The theory and numerical results are also verified through a series of model tests in a 2D wave tank.

92 citations

Journal ArticleDOI
TL;DR: This Theme Issue is intended to identify and to outline mathematical problems of modern hydroelasticity and to review recent developments in this area, including physically and mathematically elaborated models and the techniques used in their analysis.
Abstract: Hydroelasticity brings together hydrodynamics and elastic theories. It is concerned with deformations of elastic bodies responding to hydrodynamic excitations, which themselves depend on elastic deformation. This Theme Issue is intended to identify and to outline mathematical problems of modern hydroelasticity and to review recent developments in this area, including physically and mathematically elaborated models and the techniques used in their analysis.

85 citations