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Breakwater

The Experts below are selected from a list of 288 Experts worldwide ranked by ideXlab platform

Hwunghweng Hwung – 1st expert on this subject based on the ideXlab platform

  • structural permeability effects on the interaction of a solitary wave and a submerged Breakwater
    Coastal Engineering, 2003
    Co-Authors: Chingjer Huang, Hsing Han Chang, Hwunghweng Hwung

    Abstract:

    Abstract The unsteady two-dimensional Navier–Stokes equations and Navier–Stokes type model equations for porous flows were solved numerically to simulate the interaction between a solitary wave and a submerged porous Breakwater. The free surface boundary conditions and the interfacial boundary conditions between the water and the porous media are in complete form. A piston-type wavemaker, set-up in the computational domain, generated the incident solitary wave. The accuracy of the numerical model was verified by comparing the numerical results with the experimental data. Having verified the accuracy of the numerical model, the effects of several parameters on the interaction of a solitary wave and a submerged Breakwater were systematically investigated. These parameters include the incident wave height, the aspect ratio of the Breakwater, and the porosity including the impermeable case. The flow fields near the Breakwater are discussed in terms of the velocity vectors, the vortex shedding and the trajectories of the fluid particles. The pressure drag acting on the Breakwater was also calculated. The numerical results reveal that if the Breakwater width is small compared with the effective wave length, the structure permeability has no apparent effect on wave transformation. For wide porous Breakwaters, if the structure porosity is small, the increase in the porosity results in the reduction of the transmission coefficient; otherwise the transmission coefficient increases with porosity.

J. S. Mani – 2nd expert on this subject based on the ideXlab platform

  • Reef Breakwaters for Coastal Protection
    , 2020
    Co-Authors: A. Chiranjeevi Rambabu, J. S. Mani

    Abstract:

    This paper presents results of a numerical modelling study to investigate the performance of impermeable reef Breakwaters for coastal protection. The study aimed to define the effect of depth of submergence, surface width of structure and reef Breakwater spacing on wave transmission characteristics. The results identify an optimum surface width of reefs and optimum spacing between reefs. The solution is written in terms of velocity potential of the waves. The scattered portion of potential is solved numerically based on Green’s formulation. The results show that for ds/d>0.625 and Hi/gT2>0.006, the Breakwater is capable of reducing incident waves by about 60%. Results also indicate an optimum width ratio of B/d=0.75. By restricting the effective width ratio of the series of Breakwater to 0.75, studies were conducted to determine the effect of spacing between Breakwaters on the transmission coefficient, suggesting an optimum clear spacing of w/b=2.00.

  • Numerical prediction of performance of submerged Breakwaters
    Ocean Engineering, 2005
    Co-Authors: A. Chiranjeevi Rambabu, J. S. Mani

    Abstract:

    Abstract The results of a numerical model study on the transmission characteristics of a submerged Breakwater are presented. Study aimed to determine the effect of depth of submergence, crest width, initial wave conditions and material properties on the transmission characteristics of the submerged Breakwater. The results highlight the optimum crest width of the Breakwater and optimum clear spacing between two Breakwaters. A submerged permeable Breakwater with d s / d =0.5, p =0.3 and f =1.0, reduces the transmission coefficient by about 10% than the impermeable Breakwater. The results indicates an optimum width ratio of B / d =0.75 for achieving minimum transmission. By restricting the effective width ratio of the series of Breakwaters to 0.75, studies were conducted to determine the effect of clear spacing between Breakwaters on transmission coefficient, suggesting an optimum clear spacing of w / b =2.00 to obtain K t below 0.6.

  • Dynamics of Cage Floating Breakwater
    Journal of Offshore Mechanics and Arctic Engineering-transactions of The Asme, 2005
    Co-Authors: K. Murali, S. S. Amer, J. S. Mani

    Abstract:

    Floating Breakwaters have potential applications in protecting minor ports and harbors such as fisheries and recreational harbors, where-in stringent tranquillity requirements are not warranted. In field applications of the existing floating Breakwaters, limitations are imposed due to their large relative width (ratio between Breakwater width and wave length) requirements to achieve desirable tranquillity level. This relative width requirement is greater than 0.3 for the existing floating Breakwaters. To overcome the above drawback associated with the existing system a new configuration for a floating Breakwater is derived, which could yield the desired performance with minimum relative width requirement. The floating Breakwater comprises of two pontoons rigidly connected together and each of the pontoons having a row of cylinders attached beneath, for improved performance characteristics. The laboratory tests were conducted in both regular and random wave flumes to study the dynamic behavior of the Breakwater. Transmission and reflection coefficients, water surface elevations and velocities inside the cage like area provided in between the pontoons, rigid body motions floating Breakwater and mooring forces were studied under regular and random waves and under the regular waves followed by a uniform current. The results proved the suitability of the floating Breakwater to the field conditions even for large wave periods. In addition the variations in water particle kinematics, rigid body motion and mooring forces show nominal magnitudes when compared to the existing systems indicating the rigidness of the Breakwater.

Chingjer Huang – 3rd expert on this subject based on the ideXlab platform

  • structural permeability effects on the interaction of a solitary wave and a submerged Breakwater
    Coastal Engineering, 2003
    Co-Authors: Chingjer Huang, Hsing Han Chang, Hwunghweng Hwung

    Abstract:

    Abstract The unsteady two-dimensional Navier–Stokes equations and Navier–Stokes type model equations for porous flows were solved numerically to simulate the interaction between a solitary wave and a submerged porous Breakwater. The free surface boundary conditions and the interfacial boundary conditions between the water and the porous media are in complete form. A piston-type wavemaker, set-up in the computational domain, generated the incident solitary wave. The accuracy of the numerical model was verified by comparing the numerical results with the experimental data. Having verified the accuracy of the numerical model, the effects of several parameters on the interaction of a solitary wave and a submerged Breakwater were systematically investigated. These parameters include the incident wave height, the aspect ratio of the Breakwater, and the porosity including the impermeable case. The flow fields near the Breakwater are discussed in terms of the velocity vectors, the vortex shedding and the trajectories of the fluid particles. The pressure drag acting on the Breakwater was also calculated. The numerical results reveal that if the Breakwater width is small compared with the effective wave length, the structure permeability has no apparent effect on wave transformation. For wide porous Breakwaters, if the structure porosity is small, the increase in the porosity results in the reduction of the transmission coefficient; otherwise the transmission coefficient increases with porosity.