Shallow water infrastructure needs to support increased activity on the shores of Semarang.This study chooses several pontoons because of their good stability,rolling motion,and more expansive space.A coupled simulati...Shallow water infrastructure needs to support increased activity on the shores of Semarang.This study chooses several pontoons because of their good stability,rolling motion,and more expansive space.A coupled simulation method consisting of hydrodynamic and structural calculations has been used to evaluate a catamaran pontoon’s motion and structural integrity.Four different space sizes are set for the pontoon system:5 m,5.5 m,6 m,and 6.5 m.The frequency domain shows that the pontoon space affects the RAO in wave periods ranging from 3 s to 5 s.At wave periods of 3 s,4 s,and 5 s,the pontoon space significantly affects the maximum motion and chain tension parameter values,which are evaluated via time domain simulation.The critical stress of the pontoon is shown at a wave period of 5 s for 5 m and 5.5 m of pontoon space,which shows that the stress can reach 248 MPa.展开更多
For the design and operation of a floating bridge, the understanding of its dynamic behavior under a moving load is of great importance. The purpose of this paper is to investigate the dynamic performances of a new ty...For the design and operation of a floating bridge, the understanding of its dynamic behavior under a moving load is of great importance. The purpose of this paper is to investigate the dynamic performances of a new type floating bridge, the pontoon-separated floating bridge, under the effect of a moving load. In the paper, a brief summary of the dynamic analysis of the floating bridge is first introduced. The motion equations for a pontoon-separated floating bridge, considering the nonlinear properties of connectors and vehicles＇ inertia effects, are proposed. The super-element method is applied to reduce the numerical analysis scale to solve the reduced equations. Based on the static analysis, the dynamic features of the new type floating bridge subjected to a moving load are investigated. It is found that the dynamie behavior of the pontoon-separated floating bridge is superior to that of the ribbon bridge by taking the nonlinearity of eonneetors into account.展开更多
A pile-restrained pontoon-plate floating breakwater is proposed in this paper. The laboratory physical-model tests are conducted to investigate the wave-dissipation property and heave-motion response of a model. The i...A pile-restrained pontoon-plate floating breakwater is proposed in this paper. The laboratory physical-model tests are conducted to investigate the wave-dissipation property and heave-motion response of a model. The influence of the model＇s geometric parameters including relative pontoon width, plate width, number of plates and pontoon draft on wavedissipation performance and heave-motion response are discussed, as well as the correlation between these two factors. The result indicates that wave-dissipation performance of the proposed structure is better than the pontoon structure： its transmission coefficient and heave-motion height are reduced by 0.2 and 0.3, respectively, in comparison with those of the pile-restrained pontoon model at a relative pontoon width of 0.2.展开更多
A numerical model is developed by use of the boundary integral equation method to investigate the responses of a two-dimensional floating structure. The structure under consideration consisting of two pontoons, is con...A numerical model is developed by use of the boundary integral equation method to investigate the responses of a two-dimensional floating structure. The structure under consideration consisting of two pontoons, is connected by a rigid framework, and linked to the sea floor by a mooring system. The theoretical conception is based on potential theory with hnear external forces, and applied to an arbitrarily shaped body and water depth. The discussion includes the influence of draft and space between pontoons on the responses of the floating structure. Finally, the validity of the method is adequately verified by experimental results.展开更多
A numerical study adopting the 2Dδ-SPH model is performed to compare the hydrodynamic characteristics of a single pontoon floating breakwater and a double pontoon floating breakwater.Numerical simulations are perform...A numerical study adopting the 2Dδ-SPH model is performed to compare the hydrodynamic characteristics of a single pontoon floating breakwater and a double pontoon floating breakwater.Numerical simulations are performed using theδ-SPH model and experimental tests are conducted to validate the numerical model.The numerical results of both the free surface elevations and motions of the floating breakwater are in good agreement with the experimental results.Numerical results show that when the pontoon drafts are larger,the double pontoon floating breakwater performs better in wave attenuations compared with the single pontoon floating breakwater,and for all the drafts,the amplitudes of motions including sway,heave and roll of the double pontoon floating breakwater is always smaller.In addition,increasing the spacing between the two pontoons can further reduce the amplitudes of pontoon motions and improve the wave attenuation ability of the double pontoon floating breakwater.展开更多
The hydrodynamic behaviors of a floating breakwater consisting of a rectangular pontoon and horizontal plates are studied theoretically. The fluid motion is idealized as two-dimensional linear potential flow. The moti...The hydrodynamic behaviors of a floating breakwater consisting of a rectangular pontoon and horizontal plates are studied theoretically. The fluid motion is idealized as two-dimensional linear potential flow. The motions of the floating breakwater are assumed to be two-dimensional in sway, heave, and roll. The solution to the fluid motion is derived by transforming the governing differential equation into the integral equation on the boundary in time domain with the Green＇s function method. The motion equations of the floating breakwater are established and solved with the fourth-order Runge-Kutta method to obtain the displacement and velocity of the breakwater. The mooring forces are computed with the static method. The computational results of the wave transmission coefficient, the motion responses, and the mooring forces of the pontoon-plate floating breakwater are given. It is indicated that the relative width of the pontoon is an important factor influencing the wave transmission coefficient of the floating breakwater. The transmission coefficient decreases obviously as the relative width of the pontoon increases. The horizontal plates help to reduce the wave transmission over the floating breakwater. The motion responses and the mooring forces of the pontoon-plate floating breakwater are less than those of the pontoon floating breakwater. The mooring force at the offshore side is larger than that at the onshore side.展开更多
A floating breakwater(FB)has extensive potential applications in the fields of coastal,offshore,and ocean engineering owing to its advantages such as eco-friendliness,low cost,easy and rapid construction,and quick dis...A floating breakwater(FB)has extensive potential applications in the fields of coastal,offshore,and ocean engineering owing to its advantages such as eco-friendliness,low cost,easy and rapid construction,and quick dismantling and reinstallation.An FB composed of twin pontoons and multi-porous vertical plates is proposed to improve the wave attenuation performance.The wave attenuation performance is investigated for different FB structures and vertical plate types under different incident wave heights and periods using 2D wave physical model tests in a wave flume.The results demonstrate that the proposed FB has a better performance than that of the conventional single pontoon-type FB.It reduces the wave transmission due to its enhanced wave reflection and energy loss.The wave transmission coefficient of the proposed FB decreases with an increase in the number of layers and relative draft depth of the vertical plates.However,a further decrease in the wave transmission coefficient is not observed when the number of porous vertical plates is increased from 4 to 5 layers.An equation has been derived to predict the wave transmission of the proposed FB based on the experimental results.展开更多
The dynamic responses of two pontoons while connected with each other in irregular waves are calculated by means of three-dimensional （3-D） potential flow theory. The computation is to find the optimal status for co...The dynamic responses of two pontoons while connected with each other in irregular waves are calculated by means of three-dimensional （3-D） potential flow theory. The computation is to find the optimal status for connection at a certain sea state. On the basis of the relative motion of two pontoons in irregular waves, Visual FORTRAN programming language, as well as OpenGL （Open Graphics Library）, is used to develop a set of virtual reality system of the relative motion of two pontoons, which is fully interactive with realistic effect. The transfinite interpolation scheme is applied for the mesh generation of wave surface, and the wave motion is simulated by surface elevation and calculated by 3-D potential flow theory.展开更多
With the rapid development of social economy, the rapid progress of science and technology, people＇s quality of life requirements are growing higher and higher, in order to further meet the growing masses of the grow...With the rapid development of social economy, the rapid progress of science and technology, people＇s quality of life requirements are growing higher and higher, in order to further meet the growing masses of the growing sports fitness needs, the State Council in June 1995 approved the ＂ Fitness program outline＂. With the sound of physical education, sports activities are increasingly rich, but also gradually from the land movement to the development of water sports, and water power center other hand, people＇s demand for the environment pontoon project and bear the brunt of the project. On the and landscape is also rising. Water pontoon in this environment, but also toward the ecological water conservancy, landscape water direction. While the pontoon is the driving force of the economic development and social needs and other aspects to be reflected展开更多
LNG bunkering pontoons are presented to solve the fueling difficulty of LNG ships on inland waterways with a great variation of water height and channel width by seasonal change.First,the background of this concept wa...LNG bunkering pontoons are presented to solve the fueling difficulty of LNG ships on inland waterways with a great variation of water height and channel width by seasonal change.First,the background of this concept was analyzed as well as the demand of LNG bunkering pontoons,and the involved idea of levels management.Then,from the safety barrier perspective,safety design principles were discussed,the safety principles and implement measures of LNG storage were provided,LNG tanks for the pontoon were analyzed in detail in terms of their types,design pressure,material selection and leakage protection principles.Also,the safety concerns of LNG supply and bunkering process were raised,and an improved handy bunkering arm&hose,lighter and more flexible than ever before,was introduced.Berthing and unberthing are related to the survival of the pontoon so that the key points of such design were highlighted.It is concluded that(1)based on the levels management,the pontoon equipped with IMO Type C tanks,with reasonable berthing/unberthing and safety designs adopted,is proved to be safe and reliable by practices;(2)by 2025,nearly 30 such improved LNG bunkering pontoons with a fueling capacity of 500 m^(3) each will be required on Yangtze and Pearl Rivers;and(3)the pontoon's safety and reliability has been verified by practices and its fourth generation has been developed.展开更多
To investigate the hydrodynamic characteristic of pontoon bridge, the multi-block grid generation technique with numerical methods for viscous fluid dynamics is applied to numerical simulations on the hydrodynamic cha...To investigate the hydrodynamic characteristic of pontoon bridge, the multi-block grid generation technique with numerical methods for viscous fluid dynamics is applied to numerical simulations on the hydrodynamic characteristic of a ribbon ferrying raft model at a series of towing speeds. Comparison of the simulated results with the experimental data indicates that the simulated results are acceptable. It shows that the multi-block grid generation technique is effective in the computation on pontoon bridge hydrodynamics.展开更多
The objective of this study is to develop a procedure to analyze the motions of a floating pier comprised of several pontoons that are modeled as rigid bodies and connected to each other by flexible and rigid connecto...The objective of this study is to develop a procedure to analyze the motions of a floating pier comprised of several pontoons that are modeled as rigid bodies and connected to each other by flexible and rigid connectors.Recently,the use of floating piers has increased because of their advantages,such as faster and higher-quality construction,seismic force isolation for a full-scale mooring system,low dependence on local soil conditions and tides,ability to relocate or reconfigure the pier modules during the operation period and 75-100 years of repair-free service.A floating pier consists of a pier,access bridge,mooring system and fender system,each of which comes in many variations to suit different usages and construction considerations.The typical loads used in the design of these piers are dead loads,live loads,mooring loads,fender loads and environmental loads induced by wind,currents and waves.For numerical simulation,three types of piers are used:passenger piers,light-cargo piers and semi-heavy-cargo piers.The selected piers consist of several large pontoons joined by pivots and have a pile-based mooring system.These piers are modeled by SAP2000software as two-dimensional frames that are linked together.As the first step,each type of pier is subjected to loading,and its general behavior is assessed.According to this behavior,the major load combinations are described for the design of piers and analyzed to determine the behavior of the modules.Lastly,according to the analysis results and the safe use and stability considerations,such as the maximum draft and longitudinal gradient,the dimensions of each module in each pier type are presented.展开更多
Tension leg platform(TLP)is a typical compliant offshore structure for oil/gas resources exploitation.In the design process,the prediction of the free surface elevation is of great importance for the determination of ...Tension leg platform(TLP)is a typical compliant offshore structure for oil/gas resources exploitation.In the design process,the prediction of the free surface elevation is of great importance for the determination of the air gap.So far,the existing researches for predicting the air gap of the TLPs focus on the supporting columns while pay little attention to the horizontal pontoons.For the second order diffraction problem or long incident wave condition,the velocity potential decays slowly with water depth and the effect of pontoons should not be neglected.Herein the effect of pontoons on the diffracted wave field in the vicinity of a TLP platform is investigated in this study.The diffraction of regular waves by a square array of truncated cylinders and a whole TLP structure is studied in detail by using both the linear and the second-order diffraction theory.Numerical calculation is performed for the free surface elevation and wave run up.Numerical results show that the near-trapping phenomenon can occur inside the TLP and leads to significantly increased wave height.To study the effect of pontoons on the free surface elevation comparisons are carried out between the results of these two structures with and without pontoons.It is found that pontoons have an appreciable effect on the diffracted wave field for long incident regular waves and increase the largest response notably when the near-trapping phenomenon occurs at the second-order.展开更多
Modular floating structures(MFS)offer a sustainable pathway towards the expansion of coastal cities in adaptation tofilooding and sea level rise driven by climate change.It is therefore necessary to develop analytical...Modular floating structures(MFS)offer a sustainable pathway towards the expansion of coastal cities in adaptation tofilooding and sea level rise driven by climate change.It is therefore necessary to develop analytical methods easily accessible to architects or structural engineers for the rapid prototyping of MFS designs.This work develops novel closed‑form expressions describing the rigid body dynamics of symmetrically loaded rectangular pontoons across all six degrees of freedom(DOF)excited by surface waves approaching from any arbitrary direction.The derivations were based on Airy wave theory assuming frequency‑independent added mass and damping.When benchmarked against numerical solutions from ANSYS/AQWA for two MFS prototypes,the analytical approach proved capable of predicting the response amplitude operators(RAO)across all DOFs,wave directions,and structural confiigurations.However,while the response of mass‑dominated DOFs(surge,sway,and yaw)were well captured,the damping ratio for stiffness‑dominated DOFs(heave,roll,and pitch)must be judiciously selected to yield accurate RAO results.A parametric investigation further elucidated the contribution of structural geometry and wave directionality on the critical accelerations experienced by an idealizedfiloating structure founded upon a square pontoon under realistic sea states.It was discovered that the largest accelerations were triggered by waves approaching orthogonally to the pontoon.Ultimately,this work facilitates a more streamlined approach for the dynamic analysis of compliantfiloating bodies to supplement detailed modeling efforts via numerical methods.展开更多
基金financially supported by the Riset Pengembangan dan Penerapan(RPP),Diponegoro University 2023 research scheme with contract number 609-18/UN7.D2/PP/VIII/2023.
文摘Shallow water infrastructure needs to support increased activity on the shores of Semarang.This study chooses several pontoons because of their good stability,rolling motion,and more expansive space.A coupled simulation method consisting of hydrodynamic and structural calculations has been used to evaluate a catamaran pontoon’s motion and structural integrity.Four different space sizes are set for the pontoon system:5 m,5.5 m,6 m,and 6.5 m.The frequency domain shows that the pontoon space affects the RAO in wave periods ranging from 3 s to 5 s.At wave periods of 3 s,4 s,and 5 s,the pontoon space significantly affects the maximum motion and chain tension parameter values,which are evaluated via time domain simulation.The critical stress of the pontoon is shown at a wave period of 5 s for 5 m and 5.5 m of pontoon space,which shows that the stress can reach 248 MPa.
基金This project was supported by the Commission of Science Technology and Industry for National Defense .
文摘For the design and operation of a floating bridge, the understanding of its dynamic behavior under a moving load is of great importance. The purpose of this paper is to investigate the dynamic performances of a new type floating bridge, the pontoon-separated floating bridge, under the effect of a moving load. In the paper, a brief summary of the dynamic analysis of the floating bridge is first introduced. The motion equations for a pontoon-separated floating bridge, considering the nonlinear properties of connectors and vehicles＇ inertia effects, are proposed. The super-element method is applied to reduce the numerical analysis scale to solve the reduced equations. Based on the static analysis, the dynamic features of the new type floating bridge subjected to a moving load are investigated. It is found that the dynamie behavior of the pontoon-separated floating bridge is superior to that of the ribbon bridge by taking the nonlinearity of eonneetors into account.
基金supported by the National Natural Science Foundation of China(Grant No.50479054)
文摘A pile-restrained pontoon-plate floating breakwater is proposed in this paper. The laboratory physical-model tests are conducted to investigate the wave-dissipation property and heave-motion response of a model. The influence of the model＇s geometric parameters including relative pontoon width, plate width, number of plates and pontoon draft on wavedissipation performance and heave-motion response are discussed, as well as the correlation between these two factors. The result indicates that wave-dissipation performance of the proposed structure is better than the pontoon structure： its transmission coefficient and heave-motion height are reduced by 0.2 and 0.3, respectively, in comparison with those of the pile-restrained pontoon model at a relative pontoon width of 0.2.
文摘A numerical model is developed by use of the boundary integral equation method to investigate the responses of a two-dimensional floating structure. The structure under consideration consisting of two pontoons, is connected by a rigid framework, and linked to the sea floor by a mooring system. The theoretical conception is based on potential theory with hnear external forces, and applied to an arbitrarily shaped body and water depth. The discussion includes the influence of draft and space between pontoons on the responses of the floating structure. Finally, the validity of the method is adequately verified by experimental results.
基金supported by the National Natural Science Foundation of China(Grant Nos.51725903 and 52088102).
文摘A numerical study adopting the 2Dδ-SPH model is performed to compare the hydrodynamic characteristics of a single pontoon floating breakwater and a double pontoon floating breakwater.Numerical simulations are performed using theδ-SPH model and experimental tests are conducted to validate the numerical model.The numerical results of both the free surface elevations and motions of the floating breakwater are in good agreement with the experimental results.Numerical results show that when the pontoon drafts are larger,the double pontoon floating breakwater performs better in wave attenuations compared with the single pontoon floating breakwater,and for all the drafts,the amplitudes of motions including sway,heave and roll of the double pontoon floating breakwater is always smaller.In addition,increasing the spacing between the two pontoons can further reduce the amplitudes of pontoon motions and improve the wave attenuation ability of the double pontoon floating breakwater.
基金supported by the National Natural Science Foundation of China (Grant No. 51009032)the Scientific Research Foundation of Third Institute of Oceanography, SOA (Grant No. 201003)the Open Research Fund Program of Hunan Province Key Laboratory of Water, Sediment Science & Flood Hazard Prevention (Grant No. 2010SS03)
文摘The hydrodynamic behaviors of a floating breakwater consisting of a rectangular pontoon and horizontal plates are studied theoretically. The fluid motion is idealized as two-dimensional linear potential flow. The motions of the floating breakwater are assumed to be two-dimensional in sway, heave, and roll. The solution to the fluid motion is derived by transforming the governing differential equation into the integral equation on the boundary in time domain with the Green＇s function method. The motion equations of the floating breakwater are established and solved with the fourth-order Runge-Kutta method to obtain the displacement and velocity of the breakwater. The mooring forces are computed with the static method. The computational results of the wave transmission coefficient, the motion responses, and the mooring forces of the pontoon-plate floating breakwater are given. It is indicated that the relative width of the pontoon is an important factor influencing the wave transmission coefficient of the floating breakwater. The transmission coefficient decreases obviously as the relative width of the pontoon increases. The horizontal plates help to reduce the wave transmission over the floating breakwater. The motion responses and the mooring forces of the pontoon-plate floating breakwater are less than those of the pontoon floating breakwater. The mooring force at the offshore side is larger than that at the onshore side.
基金This work was financially supported by the National Key R&D Program of China(Grant No.2017YFC1404200).
文摘A floating breakwater(FB)has extensive potential applications in the fields of coastal,offshore,and ocean engineering owing to its advantages such as eco-friendliness,low cost,easy and rapid construction,and quick dismantling and reinstallation.An FB composed of twin pontoons and multi-porous vertical plates is proposed to improve the wave attenuation performance.The wave attenuation performance is investigated for different FB structures and vertical plate types under different incident wave heights and periods using 2D wave physical model tests in a wave flume.The results demonstrate that the proposed FB has a better performance than that of the conventional single pontoon-type FB.It reduces the wave transmission due to its enhanced wave reflection and energy loss.The wave transmission coefficient of the proposed FB decreases with an increase in the number of layers and relative draft depth of the vertical plates.However,a further decrease in the wave transmission coefficient is not observed when the number of porous vertical plates is increased from 4 to 5 layers.An equation has been derived to predict the wave transmission of the proposed FB based on the experimental results.
基金supported by the National Natural Science Foundation of China(Grant No.50579047)
文摘The dynamic responses of two pontoons while connected with each other in irregular waves are calculated by means of three-dimensional （3-D） potential flow theory. The computation is to find the optimal status for connection at a certain sea state. On the basis of the relative motion of two pontoons in irregular waves, Visual FORTRAN programming language, as well as OpenGL （Open Graphics Library）, is used to develop a set of virtual reality system of the relative motion of two pontoons, which is fully interactive with realistic effect. The transfinite interpolation scheme is applied for the mesh generation of wave surface, and the wave motion is simulated by surface elevation and calculated by 3-D potential flow theory.
文摘With the rapid development of social economy, the rapid progress of science and technology, people＇s quality of life requirements are growing higher and higher, in order to further meet the growing masses of the growing sports fitness needs, the State Council in June 1995 approved the ＂ Fitness program outline＂. With the sound of physical education, sports activities are increasingly rich, but also gradually from the land movement to the development of water sports, and water power center other hand, people＇s demand for the environment pontoon project and bear the brunt of the project. On the and landscape is also rising. Water pontoon in this environment, but also toward the ecological water conservancy, landscape water direction. While the pontoon is the driving force of the economic development and social needs and other aspects to be reflected
基金Project supported by the funding program of China Maritime Safety Administration and National Energy Administration“Research on the Application Safety of LNG-Fueled Vessels”(No.:MSA[2012]509).
文摘LNG bunkering pontoons are presented to solve the fueling difficulty of LNG ships on inland waterways with a great variation of water height and channel width by seasonal change.First,the background of this concept was analyzed as well as the demand of LNG bunkering pontoons,and the involved idea of levels management.Then,from the safety barrier perspective,safety design principles were discussed,the safety principles and implement measures of LNG storage were provided,LNG tanks for the pontoon were analyzed in detail in terms of their types,design pressure,material selection and leakage protection principles.Also,the safety concerns of LNG supply and bunkering process were raised,and an improved handy bunkering arm&hose,lighter and more flexible than ever before,was introduced.Berthing and unberthing are related to the survival of the pontoon so that the key points of such design were highlighted.It is concluded that(1)based on the levels management,the pontoon equipped with IMO Type C tanks,with reasonable berthing/unberthing and safety designs adopted,is proved to be safe and reliable by practices;(2)by 2025,nearly 30 such improved LNG bunkering pontoons with a fueling capacity of 500 m^(3) each will be required on Yangtze and Pearl Rivers;and(3)the pontoon's safety and reliability has been verified by practices and its fourth generation has been developed.
文摘To investigate the hydrodynamic characteristic of pontoon bridge, the multi-block grid generation technique with numerical methods for viscous fluid dynamics is applied to numerical simulations on the hydrodynamic characteristic of a ribbon ferrying raft model at a series of towing speeds. Comparison of the simulated results with the experimental data indicates that the simulated results are acceptable. It shows that the multi-block grid generation technique is effective in the computation on pontoon bridge hydrodynamics.
文摘The objective of this study is to develop a procedure to analyze the motions of a floating pier comprised of several pontoons that are modeled as rigid bodies and connected to each other by flexible and rigid connectors.Recently,the use of floating piers has increased because of their advantages,such as faster and higher-quality construction,seismic force isolation for a full-scale mooring system,low dependence on local soil conditions and tides,ability to relocate or reconfigure the pier modules during the operation period and 75-100 years of repair-free service.A floating pier consists of a pier,access bridge,mooring system and fender system,each of which comes in many variations to suit different usages and construction considerations.The typical loads used in the design of these piers are dead loads,live loads,mooring loads,fender loads and environmental loads induced by wind,currents and waves.For numerical simulation,three types of piers are used:passenger piers,light-cargo piers and semi-heavy-cargo piers.The selected piers consist of several large pontoons joined by pivots and have a pile-based mooring system.These piers are modeled by SAP2000software as two-dimensional frames that are linked together.As the first step,each type of pier is subjected to loading,and its general behavior is assessed.According to this behavior,the major load combinations are described for the design of piers and analyzed to determine the behavior of the modules.Lastly,according to the analysis results and the safe use and stability considerations,such as the maximum draft and longitudinal gradient,the dimensions of each module in each pier type are presented.
基金supported by the National Natural Science Foundation of China(Grant Nos.11072052,51221961)the National Basic Research Program of China("973"Project)(Grant No.2011CB013703)
文摘Tension leg platform(TLP)is a typical compliant offshore structure for oil/gas resources exploitation.In the design process,the prediction of the free surface elevation is of great importance for the determination of the air gap.So far,the existing researches for predicting the air gap of the TLPs focus on the supporting columns while pay little attention to the horizontal pontoons.For the second order diffraction problem or long incident wave condition,the velocity potential decays slowly with water depth and the effect of pontoons should not be neglected.Herein the effect of pontoons on the diffracted wave field in the vicinity of a TLP platform is investigated in this study.The diffraction of regular waves by a square array of truncated cylinders and a whole TLP structure is studied in detail by using both the linear and the second-order diffraction theory.Numerical calculation is performed for the free surface elevation and wave run up.Numerical results show that the near-trapping phenomenon can occur inside the TLP and leads to significantly increased wave height.To study the effect of pontoons on the free surface elevation comparisons are carried out between the results of these two structures with and without pontoons.It is found that pontoons have an appreciable effect on the diffracted wave field for long incident regular waves and increase the largest response notably when the near-trapping phenomenon occurs at the second-order.
文摘Modular floating structures(MFS)offer a sustainable pathway towards the expansion of coastal cities in adaptation tofilooding and sea level rise driven by climate change.It is therefore necessary to develop analytical methods easily accessible to architects or structural engineers for the rapid prototyping of MFS designs.This work develops novel closed‑form expressions describing the rigid body dynamics of symmetrically loaded rectangular pontoons across all six degrees of freedom(DOF)excited by surface waves approaching from any arbitrary direction.The derivations were based on Airy wave theory assuming frequency‑independent added mass and damping.When benchmarked against numerical solutions from ANSYS/AQWA for two MFS prototypes,the analytical approach proved capable of predicting the response amplitude operators(RAO)across all DOFs,wave directions,and structural confiigurations.However,while the response of mass‑dominated DOFs(surge,sway,and yaw)were well captured,the damping ratio for stiffness‑dominated DOFs(heave,roll,and pitch)must be judiciously selected to yield accurate RAO results.A parametric investigation further elucidated the contribution of structural geometry and wave directionality on the critical accelerations experienced by an idealizedfiloating structure founded upon a square pontoon under realistic sea states.It was discovered that the largest accelerations were triggered by waves approaching orthogonally to the pontoon.Ultimately,this work facilitates a more streamlined approach for the dynamic analysis of compliantfiloating bodies to supplement detailed modeling efforts via numerical methods.
