群遮效应对海上结构物波漂移力的低减作用
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摘要
针对波浪作用下海上浮式建筑物的波漂移力问题,考虑在海上建筑物周围合理地布设小型浮体群以降低海上建筑物的波漂移力。本文基于波浪交互理论和高阶边界元方法,建立了分析三维多浮体间群遮效应的数值模型。计算结果表明:通过优化外围浮体的尺寸可以降低海上建筑物的波漂移力;本数值模型计入了浮体间的波浪相互干涉作用,对群遮效应的预报更加准确和接近工程实际问题。随着入射波频率的不同,发生群遮效应所对应的外围浮体尺寸不同;群遮效应不仅可以降低所需防护海上建筑物的波漂移力,也可以降低整个浮体群的波漂移力。
This study aims to examine the reduction in the wave drift force acting on a floating structure,such as an offshore platform,by appropriate positioning of small floating bodies around the floating structure. To investigate the cloaking phenomenon on 3 D multiple floating bodies,a numerical model using a combination of wave interaction theory and the higher-order boundary element method is introduced. Computed results show that reduction in the wave drift force on the offshore structure is realized using optimized parameters of the surrounding floating bodies.Numerical computations were highly accurate and benefited from considering the interactions between multi-bodies,and the optimized parameters of the surrounding bodies were different in relation to the various wave frequencies. Results show that the cloaking phenomenon can reduce the wave drift force on the central structure and on the entire array of floating bodies.
This study aims to examine the reduction in the wave drift force acting on a floating structure,such as an offshore platform,by appropriate positioning of small floating bodies around the floating structure. To investigate the cloaking phenomenon on 3 D multiple floating bodies,a numerical model using a combination of wave interaction theory and the higher-order boundary element method is introduced. Computed results show that reduction in the wave drift force on the offshore structure is realized using optimized parameters of the surrounding floating bodies.Numerical computations were highly accurate and benefited from considering the interactions between multi-bodies,and the optimized parameters of the surrounding bodies were different in relation to the various wave frequencies. Results show that the cloaking phenomenon can reduce the wave drift force on the central structure and on the entire array of floating bodies.
引文
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[2]缪泉明,顾民,杨占明,等.极限海况下浮标运动及锚链受力估算[J].船舶力学,2003,7(5):21-27.MIU Quanming,GU Min,YANG Zhanming,et al.Estimation of buoy motions and chain forces in extreme sea state[J].Journal of ship mechanics,2003,7(5):21-27.
[3]PENDRY J B,SCHURIG D,SMITH D R.Controlling electromagnetic filed[J].Science,2006,312:1780-1782.
[4]ZIGONEANU L,POPA B,CUMMER S A.Three-dimensional broadband omnidirectional acoustic ground cloak[J].Nature materials,2014,13(4):352-355.
[5]BRULE S,JAVELAUD E H,ENOCH S,et al.Experiments on seismic metamaterials:molding surface waves[J].Physical review letters,2014,112(13):133901.
[6]ALAM M.Broadband cloaking in stratified seas[J].Physical review letters,2011,108:1-5.
[7]PORTER R.Cloaking of a cylinder in waves[C]//26thInternational Workshop on Water Waves and Floating Bodies,Greece,2011,36:1-4.
[8]NEWMAN J N.Cloaking a circular cylinder in deep water[C]//28thInternational Workshop on Water Waves and Floating Bodies,L'isle surla Sorgue,France,2013:157-160.
[9]OHKUSU M.Hydrodynamic forces on multiple cylinders in waves[C]//The Process of International Symposium Dynamics of Marine Vehicles and Structures in Waves,London,1974:261-268.
[10]KAGENOTO H,YUE D K P.Three-dimensional bodies in water waves:an exact algebraic method[J].Journal of fluid mechanics,1986,166:189-209.
[11]LINTON C M,EVANS D V.The interaction of waves with arrays of cylinders[J].Journal of fluid mechanics,1990,215:549-569.
[12]KASHIWAGI M.3-D calculation for multiple floating bodies in proximity using wave interaction theory[J].Journal of offshore and polar engineering,2008,18:1-7.
[13]MARUO H.The drift of a body floating on waves[J].Journal of ship research,1960,4:1-10.
[14]KASHIWAGI M,YOSHIDA S.Wave drift force and moment on a VLFS supported by a great number of floating columns[J].International journal of offshore and polar engineering,2001,11:176-183.
[15]FANG M C,CHEN G R.On three-dimension solution of drift forces and moments between two ships in waves[J].Journal of ship research,2002,46(4):280-28.