http://scholars.ntou.edu.tw/handle/123456789/6 2026-04-28T10:16:47Z http://scholars.ntou.edu.tw/handle/123456789/26553 標題: 小水線面雙體離岸風電人員運輸船耐海性能評估 作者: 方志中; 何達立 2025-01-01T00:00:00Z http://scholars.ntou.edu.tw/handle/123456789/26543 標題: Hydrodynamic performance of a viscoelastic flexible membrane floating over a submerged rubble mound breakwater under oblique wave incidence 作者: Swami, Kailash Chand; Koley, Santanu; Tsai, Chia-Cheng 摘要: This study investigates the scattering of oblique water waves by a viscoelastic membrane placed over a trapezoidal rubble-mound breakwater on a sloped seabed. This study considers both wave scattering and trapping when a partially reflecting seawall is positioned downstream. The boundary value problem related to the present physical setup is solved using the hybrid boundary element method-based approach by coupling the central difference scheme with the boundary element method (BEM) to handle the second-order dynamic boundary condition of the viscoelastic floating flexible membrane. The flow through the rubble mound porous breakwater is modeled using the Sollitt and Cross ["Wave transmission through permeable breakwaters," in Coastal Engineering (ASCE, 1972), pp. 1827-1846] model, while the flow through the flexible floating viscoelastic membrane is described based on the formulation presented by Agarwal et al. [J. Fluids Struct. 129, 104167 (2024)]. According to the given model, the transmitted energy is below 30% for moderate values of the viscoelastic damping parameter of the membrane. The moderate values of the breakwater's porosity and structural size are suitable for optimal performance of the present configuration of the viscoelastic membrane-breakwater setup. Also, the wave run-up coefficient, reflected energy, and wave force acting on the partially reflecting seawall show an oscillatory pattern for numerous values of seawall coefficient and inclination angle when plotted as a function of relative spacing between the breakwater and seawall. A rubble-mound breakwater combined with a viscoelastic flexible membrane effectively reduces wave energy, creating a calmer lee side zone. 2025-08-01T00:00:00Z http://scholars.ntou.edu.tw/handle/123456789/26540 標題: Modeling an array of surface-piercing piezoelectric plate wave energy converters for wave power absorption 作者: Sarkar, Biman; De, Soumen; Tsai, Chia-Cheng; Hsu, Tai-Wen 摘要: In recent years, the pursuit of sustainable ocean energy has accelerated, with wave energy conversion technologies emerging as a promising avenue for low-power electricity generation. Among various approaches, extracting electrical energy from ocean waves through piezoelectric mechanisms offers an innovative and eco-friendly solution. Acting as flexible plate-type wave energy converters, these structures are designed to efficiently capture the hydrodynamic energy of surface waves. The primary motivation behind this work arises from the observation that surface-piercing, vertically oriented piezoelectric plate-type wave energy converters have not been reported in the existing literature, to the best of the authors' knowledge. Despite their significant potential for practical marine energy applications, vertical piezoelectric configurations can provide advantages in achieving the optimum electrical load resistance, thereby maximizing harvested power, compared to horizontally oriented configurations (Kazemi et al., 2021). To overcome the mathematical complexities associated with the coupling between structural flexibility and piezoelectric interactions, a rigorous semi-analytical framework is developed. These complexities arise due to boundary conditions that involve higher-order derivatives with complex-valued coefficients. The governing problem is reformulated into a set of coupled integral equations by employing Green's function solutions along with mixed Fourier transform techniques. These equations are subsequently solved through a Singularity-Respecting Galerkin approximation, yielding accurate evaluations of the hydrodynamic response, including the reflection characteristics, wave power absorption efficiency and hydrodynamic wave forces. Furthermore, a comprehensive parametric investigation is undertaken to elucidate the influences of wave and structural parameters on plate deflection, bending moments and shear forces. Deploying multiple piezoelectric plates in an array has been found to be a more promising approach for wave power absorption. Widening the spacing between adjacent plates greatly influences the deflection of the leeward plate, regardless of whether the edges are clamped-clamped or clamped-free. The outcomes offer valuable physical insights into the energy extraction capability and dynamic behavior of the proposed array of surface-piercing piezoelectric plate-type wave energy converters. 2026-01-01T00:00:00Z http://scholars.ntou.edu.tw/handle/123456789/26537 標題: Scattering of capillary-gravity waves by surface-piercing porous barriers in the presence of uniform current over a porous sea bed 作者: Sahoo, Gagan; Behera, Harekrushna; Hsu, Tai-Wen 摘要: Capillary-gravity waves, influenced by both surface tension and gravity, interact strongly with marine structures, especially in the presence of uniform currents. Despite extensive studies on wave scattering by porous structures, the combined effects of surface tension, current, and porous barriers over a porous bottom remain insufficiently explored. This study examines the scattering of such waves by two thin surface-piercing porous barriers in the presence of a uniform current over a porous sea bed. A linear wave-structure interaction model is solved numerically through a hybrid Boundary Element-Finite Difference Method (BEM-FDM) and analytically through an eigenfunction expansion combined with a least-squares approach. The hybrid BEM-FDM efficiently handles higher-order boundary conditions that cannot be directly addressed by conventional BEM, while the analytical method eliminates the need for eigenfunction orthogonality and explicit mode coupling. The effects of surface tension, current velocity and direction, porous effect parameters of barriers as well as bottom, barrier length and spacing between them on reflection, transmission, and energy dissipation are analyzed. Results show that surface tension enhances reflection and dissipation while reducing transmission. Current direction strongly affects scattering: following currents enhance transmission, whereas opposing currents increase reflection and dissipation. Longer barriers and larger porous-effect parameters of both porous barriers and porous bottom enhance energy dissipation, while spacing between porous barriers induce interference driven oscillations. 2026-01-01T00:00:00Z