Smoothed particle hydrodynamics（SPH） is a mesh-free adaptive Lagrangian particle method with attractive features for dealing with the free surface flow.This paper applies the SPH method to simulate the large-amplitu...Smoothed particle hydrodynamics（SPH） is a mesh-free adaptive Lagrangian particle method with attractive features for dealing with the free surface flow.This paper applies the SPH method to simulate the large-amplitude lateral sloshing both with and without a floating body,and the vertical parametrically-excited sloshing in a two-dimensional tank.The numerical results show that the SPH approach has an obvious advantage over conventional mesh-based methods in handling nonlinear sloshing problems such as violent fluid-solid interaction,and flow separation and wave-breaking on the free fluid surface.The SPH method provides a new alternative and an effective way to solve these special strong nonlinear sloshing problems.展开更多
In this work,the nonlinear behaviors of soft cantilevered pipes containing internal fluid flow are studied based on a geometrically exact model,with particular focus on the mechanism of large-amplitude oscillations of...In this work,the nonlinear behaviors of soft cantilevered pipes containing internal fluid flow are studied based on a geometrically exact model,with particular focus on the mechanism of large-amplitude oscillations of the pipe under gravity.Four key parameters,including the flow velocity,the mass ratio,the gravity parameter,and the inclination angle between the pipe length and the gravity direction,are considered to affect the static and dynamic behaviors of the soft pipe.The stability analyses show that,provided that the inclination angle is not equal to π,the soft pipe is stable at a low flow velocity and becomes unstable via flutter once the flow velocity is beyond a critical value.As the inclination angle is equal to π,the pipe experiences,in turn,buckling instability,regaining stability,and flutter instability with the increase in the flow velocity.Interestingly,the stability of the pipe can be either enhanced or weakened by varying the gravity parameter,mainly dependent on the value of the inclination angle.In the nonlinear dynamic analysis,it is demonstrated that the post-flutter amplitude of the soft pipe can be extremely large in the form of limit-cycle oscillations.Besides,the oscillating shapes for various inclination angles are provided to display interesting dynamical behaviors of the inclined soft pipe conveying fluid.展开更多
An effective computational method is developed for dynamic analysis offluid-structure interaction problems involving large-amplitude sloshing of the fluid andlarge-displacement motion of the structure. The structure i...An effective computational method is developed for dynamic analysis offluid-structure interaction problems involving large-amplitude sloshing of the fluid andlarge-displacement motion of the structure. The structure is modeled as a rigid container supportedby a system consisting of springs and dashpots. The motion of the fluid is decomposed into twoparts: the large-displacement motion with the container and the large-amplitude sloshing relative tothe container. The former is conveniently dealt with by defining a container-fixed noninertiallocal frame, while the latter is easily handled by adopting an ALE kinematical description. Thisleads to an easy and accurate treatment of both the fluid-structure interface and the fluid freesurface without producing excessive distortion of the computational mesh. The coupling between thefluid and the structure is accomplished through the coupling matrices that can be easilyestablished. Two numerical examples, including a TLD-structure system and a simplified liquid-loadedvehicle system, are presented to demonstrate the effectiveness and reliability of the proposedmethod. The present work can also be applied to simulate fluid-structure problems incorporatingmultibody systems and several fluid domains.展开更多
The Haizhou and Daya bays are chosen as basins for seiche research in this paper. By reducing the astronomical tide, we obtain residuals which include seiches from the original observed tide curve of two representativ...The Haizhou and Daya bays are chosen as basins for seiche research in this paper. By reducing the astronomical tide, we obtain residuals which include seiches from the original observed tide curve of two representative gauges of the Haizhou and Daya bays, with a time resolution of 1min. We have further made a statistical analysis of the characteristics of the seasonal distribution of seiches and by making a comparative analysis of the seiches and the corresponding weather system, studied the origin of seiches. The research findings are of important reference value for the ocean engineering design and the storm surge forecast.展开更多
Seiches are long-period standing waves with a unique period called a natural resonant period,during which the phenomenon of resonance occurs.The occurrence of resonance in coastal areas can cause destruction to surrou...Seiches are long-period standing waves with a unique period called a natural resonant period,during which the phenomenon of resonance occurs.The occurrence of resonance in coastal areas can cause destruction to surrounding natural and man-made structures.By determining the resonant period of a given basin,we can pinpoint the conditions that allow waves to achieve resonance.In this study,a mathematical model is developed from the shallow water equations to examine seiches and resonances in various types of closed basin.The developed model is solved analytically using the separation of variables method to determine the seiches’fundamental resonant periods.Comparisons between the analytical solutions and experimental measurements for resonant periods are also provided.It is shown that the analytical resonant period confirms the experimental data for closed basin of various geometric profiles.Using a finite volume method on a staggered grid,the model is solved numerically to simulate the wave profile when resonance phenomenon occurs.Through those numerical simulations,we also obtain the fundamental resonant period for each basin which agrees with the derived analytical period.展开更多
利用 23 a （1964—1986 年）的假潮资料，讨论了龙口港假潮的振幅、频率、周期和持续时间等；给出了导致假潮的各种天气形势和风场；分析了不同气象要素对假潮的贡献；探讨了大和特大振幅假潮的成因。分析结果表明：风场变化是导致龙...利用 23 a （1964—1986 年）的假潮资料，讨论了龙口港假潮的振幅、频率、周期和持续时间等；给出了导致假潮的各种天气形势和风场；分析了不同气象要素对假潮的贡献；探讨了大和特大振幅假潮的成因。分析结果表明：风场变化是导致龙口港假潮的直接原因；100 cm 左右和 >150 cm 的大和特大振幅假潮，是龙口港特殊地理环境、港湾及附近大范围海域骤猛的向港爆发性大风尤其强雷暴大风涌水在港内骤然积聚和海水惯性振荡的综合结果，该假潮具有较大危害性。展开更多
基金National Science Foundation of China under Grant No. 51279133Open Research Fund Program of State Key Laboratory of Hydro-science and Engineering under Grant No. SKLHSE-2011-C-02
文摘Smoothed particle hydrodynamics（SPH） is a mesh-free adaptive Lagrangian particle method with attractive features for dealing with the free surface flow.This paper applies the SPH method to simulate the large-amplitude lateral sloshing both with and without a floating body,and the vertical parametrically-excited sloshing in a two-dimensional tank.The numerical results show that the SPH approach has an obvious advantage over conventional mesh-based methods in handling nonlinear sloshing problems such as violent fluid-solid interaction,and flow separation and wave-breaking on the free fluid surface.The SPH method provides a new alternative and an effective way to solve these special strong nonlinear sloshing problems.
基金Project supported by the National Natural Science Foundation of China(Nos.11672115,11622216,and 11972167)。
文摘In this work,the nonlinear behaviors of soft cantilevered pipes containing internal fluid flow are studied based on a geometrically exact model,with particular focus on the mechanism of large-amplitude oscillations of the pipe under gravity.Four key parameters,including the flow velocity,the mass ratio,the gravity parameter,and the inclination angle between the pipe length and the gravity direction,are considered to affect the static and dynamic behaviors of the soft pipe.The stability analyses show that,provided that the inclination angle is not equal to π,the soft pipe is stable at a low flow velocity and becomes unstable via flutter once the flow velocity is beyond a critical value.As the inclination angle is equal to π,the pipe experiences,in turn,buckling instability,regaining stability,and flutter instability with the increase in the flow velocity.Interestingly,the stability of the pipe can be either enhanced or weakened by varying the gravity parameter,mainly dependent on the value of the inclination angle.In the nonlinear dynamic analysis,it is demonstrated that the post-flutter amplitude of the soft pipe can be extremely large in the form of limit-cycle oscillations.Besides,the oscillating shapes for various inclination angles are provided to display interesting dynamical behaviors of the inclined soft pipe conveying fluid.
基金This project is supported by National 863 Hi-Tech Project Foundation (No. 2002AA411030).
文摘An effective computational method is developed for dynamic analysis offluid-structure interaction problems involving large-amplitude sloshing of the fluid andlarge-displacement motion of the structure. The structure is modeled as a rigid container supportedby a system consisting of springs and dashpots. The motion of the fluid is decomposed into twoparts: the large-displacement motion with the container and the large-amplitude sloshing relative tothe container. The former is conveniently dealt with by defining a container-fixed noninertiallocal frame, while the latter is easily handled by adopting an ALE kinematical description. Thisleads to an easy and accurate treatment of both the fluid-structure interface and the fluid freesurface without producing excessive distortion of the computational mesh. The coupling between thefluid and the structure is accomplished through the coupling matrices that can be easilyestablished. Two numerical examples, including a TLD-structure system and a simplified liquid-loadedvehicle system, are presented to demonstrate the effectiveness and reliability of the proposedmethod. The present work can also be applied to simulate fluid-structure problems incorporatingmultibody systems and several fluid domains.
文摘The Haizhou and Daya bays are chosen as basins for seiche research in this paper. By reducing the astronomical tide, we obtain residuals which include seiches from the original observed tide curve of two representative gauges of the Haizhou and Daya bays, with a time resolution of 1min. We have further made a statistical analysis of the characteristics of the seasonal distribution of seiches and by making a comparative analysis of the seiches and the corresponding weather system, studied the origin of seiches. The research findings are of important reference value for the ocean engineering design and the storm surge forecast.
基金This work was supported by the ITB Research Grant.
文摘Seiches are long-period standing waves with a unique period called a natural resonant period,during which the phenomenon of resonance occurs.The occurrence of resonance in coastal areas can cause destruction to surrounding natural and man-made structures.By determining the resonant period of a given basin,we can pinpoint the conditions that allow waves to achieve resonance.In this study,a mathematical model is developed from the shallow water equations to examine seiches and resonances in various types of closed basin.The developed model is solved analytically using the separation of variables method to determine the seiches’fundamental resonant periods.Comparisons between the analytical solutions and experimental measurements for resonant periods are also provided.It is shown that the analytical resonant period confirms the experimental data for closed basin of various geometric profiles.Using a finite volume method on a staggered grid,the model is solved numerically to simulate the wave profile when resonance phenomenon occurs.Through those numerical simulations,we also obtain the fundamental resonant period for each basin which agrees with the derived analytical period.
文摘利用 23 a （1964—1986 年）的假潮资料，讨论了龙口港假潮的振幅、频率、周期和持续时间等；给出了导致假潮的各种天气形势和风场；分析了不同气象要素对假潮的贡献；探讨了大和特大振幅假潮的成因。分析结果表明：风场变化是导致龙口港假潮的直接原因；100 cm 左右和 >150 cm 的大和特大振幅假潮，是龙口港特殊地理环境、港湾及附近大范围海域骤猛的向港爆发性大风尤其强雷暴大风涌水在港内骤然积聚和海水惯性振荡的综合结果，该假潮具有较大危害性。
