The Experts below are selected from a list of 7341 Experts worldwide ranked by ideXlab platform
Na Zhang - One of the best experts on this subject based on the ideXlab platform.
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Wave load on submerged quarter-circular and semicircular Breakwaters under irregular waves
Coastal Engineering, 2017Co-Authors: Xue Lian Jiang, Na ZhangAbstract:Abstract Laboratory experiments were conducted to investigate the characteristics of wave loading on submerged circular-front Breakwaters due to irregular waves. The wave force spectrum for a semicircular breakwater is similar to that for a quarter-circular breakwater. The dimensionless peak wave force for irregular waves is less than that for regular waves. The performance of our theoretical wave load model is improved significantly by incorporating the effect of wave transmission and flow separation. A RANS-VOF model was used to investigate the effect of local hydrodynamic disturbances by submerged Breakwaters on the pressure distribution around the breakwater and total wave load. The numerical results reveal that wave-induced vortices at the structure have a substantial influence on the wave loading on the submerged quarter-circular breakwater but not on the semicircular breakwater. A parametric analysis is required to further improve the relationship between wave loads and the vortices.
Karsten Lindegaard Jensen - One of the best experts on this subject based on the ideXlab platform.
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an experimental and numerical study of floating Breakwaters
Coastal Engineering, 2018Co-Authors: Erik Damgaard Christensen, Harry B Bingham, Andreas Peter Skou Friis, Alexander Kruse Larsen, Karsten Lindegaard JensenAbstract:Abstract Breakwaters are used to provide sheltered areas for loading and unloading of ships, and coastal protection. Often the Breakwaters are bottom mounted such as rubble mound Breakwaters. However, there can be several advantages to use a Floating Breakwater (FB). Therefore, the objective of this paper is to study the effect of two different damping mechanisms of a floating breakwater. Three basic cross-sections of FBs were tested and analysed in 2D; a regular pontoon (RG), a regular pontoon with wing plates attached (WP), and a regular pontoon with wing plates and porous media attached to the sides (WP P100). The damping of the FB motions was due to wave radiation and viscous damping. The viscous damping originated mainly from vortex generation around the edges of the structure and due to energy loss inside the porous material attached to the vertical sides of the floating breakwater. Attaching wing plates to the floating breakwater significantly reduced the motion, which was also anticipated. When the porous sides were attached the motion of the FB increased compared to the (WP) cross-section, but the wave transmission was reduced. The possibility for incorporating the effect of the damping in the radiation/diffraction code WAMIT was assessed. The study showed that the cross section with wing plates reduced the motions of the breakwater to the largest extend, while the cross section with wing plates and porous media attached to the sides reduced the reflection and transmission most effectively.
Yize Wang - One of the best experts on this subject based on the ideXlab platform.
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numerical investigations and optimizations of typical submerged box type floating Breakwaters using sph
Ocean Engineering, 2020Co-Authors: Zhenqing Liu, Yize WangAbstract:Abstract Box-type floating Breakwaters have been studied extensively. However, the examinations of the performances of them with different shapes or different numbers of boxes are limited. In addition, if it is possible to optimize the floating Breakwaters by combining the optimized parameters in separated testing groups is still unclear. Consequently, in this study, four typical box-type floating Breakwaters, i.e., dual rectangular breakwater, single rectangular breakwater, dual circular breakwater, and single circular breakwater, are selected to do extensive investigations using SPH. The coupling between DualSPHysics and MoorDyn is implemented and verified, and the coupled code can be applied to simulate the interactions between waves and moored floating structures. A total of 88 cases are modeled, and the effects of the geometry parameters on wave-attenuation performances of the Breakwaters are clarified. The numerical results show that the performances of the Breakwaters are greatly sensitive to the immersion depth. In general, the larger and lighter the Breakwaters, the better the performances will be. Meanwhile, the dual rectangular breakwater performs the best in wave attenuations, and its motions and forces are smaller than single Breakwaters. Importantly, combining the optimized parameters in each separated testing group is found to be effective to optimize the floating Breakwaters.
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numerical studies of submerged moored box type floating Breakwaters with different shapes of cross sections using sph
Coastal Engineering, 2020Co-Authors: Zhenqing Liu, Yize WangAbstract:Abstract The wave-attenuation performances and hydrodynamics of moored box-type floating Breakwaters with the same weight, same wall thickness, and six different cross-sections, i.e. circular, triangle-down, triangle-up, rectangular, trapezoid-down, and trapezoid-up, are investigated numerically using the smoothed particle hydrodynamics (SPH) method. Coupling between DualSPHysics and MoorDyn is implemented in the coupled SPH-mooring model. The effects of the key parameters, such as the breakwater density, immersion depth, ballast-water gravity, and wave condition, on wave-attenuation performance are examined systematically. The results reveal that the performances of floating Breakwaters are significantly affected by the immersion depth and wave condition, however, they are hardly affected by density and ballast-water gravity. Furthermore, the top deck is found to be an extremely effective part of a well-designed breakwater, and asymmetrical designs such as longer top-faces and shorter bottom-faces should be adopted for achieving reasonable material utilizations. Irrespective of the shapes of the cross-sections, the best performances of the different Breakwaters are almost at the same level after careful designs are implemented. Importantly, a strong relationship is identified between the motions, mooring tensions, and wave-attenuation performances, which implies that the motions are directly proportional to the wave-attenuation performances and the mooring tensions.
Yalcin Yuksel - One of the best experts on this subject based on the ideXlab platform.
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deformation of rubble mound Breakwaters under cyclic loads
Coastal Engineering, 2011Co-Authors: Kubilay Cihan, Yalcin YukselAbstract:Rubble-mound Breakwaters usually consist of a core of small quarry-run rock protected by one or more intermediate layers or underlayers that separate the core from the cover layers, which are composed of large armor units. Failure of rubble-mound Breakwaters may be due to effects such as removal or damage of the armor units, overtopping leading to scouring, toe erosion, loss of the core material, or foundation problems under waves. However, whether rubble mounds fail under seismic loads is unknown. High seismic activity can lead to large settlements and even to failure of the Breakwaters. The design of coastal structures should take into account the most relevant factors in each case, including seismic loading. The objective of this study is to understanding the failure mechanisms of conventional breakwater structures under seismic loads on rigid foundations. Hence, an experimental study was carried out on conventional breakwater structures with and without toes, subjected to different dynamic loadings of variable frequencies and amplitudes, in a shaking tank. A shaking tank with a single degree of freedom was developed to study the simple responses of conventional rubble-mound Breakwaters under cyclic loads. For each test, an automatic raining crane system was used to achieve the same relative density and porosity of the core material. The input motion induced horizontal accelerations of different magnitudes during the tests. The accelerations and the deformation phases of the model were measured by a data acquisition system and an image processing system. The experiments on the conventional rubble-mound type breakwater model were performed under rigid-bottom conditions. The model's scale was 1:50. Cyclic responses of Breakwaters with toes and without toes were examined separately, and their behaviors were compared. The results were compared with a numerical study, and the material properties and failure modes were thus defined.
Xue Lian Jiang - One of the best experts on this subject based on the ideXlab platform.
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Wave load on submerged quarter-circular and semicircular Breakwaters under irregular waves
Coastal Engineering, 2017Co-Authors: Xue Lian Jiang, Na ZhangAbstract:Abstract Laboratory experiments were conducted to investigate the characteristics of wave loading on submerged circular-front Breakwaters due to irregular waves. The wave force spectrum for a semicircular breakwater is similar to that for a quarter-circular breakwater. The dimensionless peak wave force for irregular waves is less than that for regular waves. The performance of our theoretical wave load model is improved significantly by incorporating the effect of wave transmission and flow separation. A RANS-VOF model was used to investigate the effect of local hydrodynamic disturbances by submerged Breakwaters on the pressure distribution around the breakwater and total wave load. The numerical results reveal that wave-induced vortices at the structure have a substantial influence on the wave loading on the submerged quarter-circular breakwater but not on the semicircular breakwater. A parametric analysis is required to further improve the relationship between wave loads and the vortices.
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numerical simulation on hydraulic performances of quarter circular breakwater
China Ocean Engineering, 2008Co-Authors: Xue Lian Jiang, Hanbin Gu, Yanbao LiAbstract:Quarter circular breakwater (QCB) is a new-type breakwater developed from semi-circular breakwater (SCB). The superstructure of QCB is composed of a quarter circular front wall, a horizontal base slab and a vertical rear wall. The width of QCB's base slab is about half that of SCB, which makes QCB suitable to be used on relatively firm soil foundation. The numerical wave flume based on the Reynolds averaged Navier-Stokes equations for impressible viscosity fluid is adopted in this paper to simulate the hydraulic performances of QCB. Since the geometry of both Breakwaters is similar and SCB has been studied in depth, the hydraulic performances of QCB are given in comparison with those of SCB.