| As an important coastal protection structure,breakwaters are often used to protect against waves.Compared to the relatively large cost of traditional sit-on-bottom breakwaters,floating breakwaters have a wider engineering significance due to their low cost and rapid arrangement,and are therefore receiving more and more attention from scholars and researchers.However,the research work of scholars at home and abroad is mainly focused on the linear arrangement of floating breakwaters,and little research has been done on the heterogeneous arrangement of floating breakwaters.Compared with the linear arrangement of floating breakwaters,its cover effect in the multi-wake direction is better,but due to the asymmetry of its mooring system and floating load,the overall hydrodynamic response is more complex,and the characteristics of its response need to be studied.In this paper,two heterogeneous layouts of floating breakwaters are proposed for a sea area in the South China Sea,for which corresponding mooring systems are designed and their overall hydrodynamic performance is studied numerically in comparison.The main research elements of this paper include.(1)In order to cope with multi-wake environmental conditions,two heterogeneous layouts,i.e.curved and V-shaped layout forms,are proposed for a double cylinder type floating breakwater based on the target sea state,cover and conditions,while a linear layout form is given as a comparison for hydrodynamic analysis,and corresponding mooring arrangements are designed for each layout.(2)The three mooring analysis methods are introduced,and the mooring system design is carried out for the three designed layouts considering the target environment,topography and cover requirements.The tensions under the two heterogeneous layouts are calculated using the concentrated mass method,and the mooring forces for the less stressed arc layout are provided and analysed.(3)Simulations in the frequency and time domains were carried out for the arc-shaped layout using the uncoupled calculation method,and the frequency domain spectra of its additional mass,radiation damping and motion response amplitude operator were obtained,and its six-degree-of-freedom motion response was calculated using the fully coupled calculation method.(4)The linear layout as a comparative analysis was analysed in the frequency domain and time domain to obtain its frequency domain hydrodynamic performance,and the wave frequency and low frequency motion response of the floating body was jointly solved in the time domain.The comparative analysis provides the basis for the subsequent(5)The hydrodynamic response of the linear layout was compared with that of the curved layout to compare their performance in the frequency and time domains.The frequency domain comparison results show that the arc layout has greater additional mass and radiation damping in the longitudinal rocking degrees of freedom than in the other degrees of freedom;the motion response amplitude operator has larger values at low frequencies for both layouts,with the main motion responses occurring in the longitudinal,transverse and transverse rocking degrees of freedom.The time domain comparison results show that the forces are less in the linear layout for transverse waves and less in the arc layout for oblique waves,and the mooring tensions are generally comparable in both layouts,with the mooring safety factors meeting the code requirements.In terms of the main motion response,the linear layout is relatively larger in terms of longitudinal and transverse motion response,and the transverse motion response is more violent under transverse wave conditions,while the transverse motion response is relatively mild under oblique wave conditions,and the transverse motion response is more influenced by the wave direction,while the motion response under the arc layout is less influenced by the wave direction,and the overall motion is smoother and has better hydrodynamic performance. |
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