A new wave modeling method and a level of detail (LOD) scheme are proposed for ocean surface simulation in this paper.The modeling method describes ocean wave by modifying the sine wave,and gets wave direction at any ...A new wave modeling method and a level of detail (LOD) scheme are proposed for ocean surface simulation in this paper.The modeling method describes ocean wave by modifying the sine wave,and gets wave direction at any position of ocean surface under any ocean floor conditions using wave num decomposition.LOD scheme is proposed based on quad-tree block,which simplifies the ocean surface regular mesh and realizes the real-time rendering of large-scale ocean surface.Experimental results show that these methods can get realistic effect and fast rendering speed,which are appropriated to the applications of 3D games and battlefield simulation.展开更多
Wave transmission and overtopping around nearshore breakwaters can have significant influence on the transmitted wave parameters,which affects wave conditions and sediment transportation and becomes the focus of desig...Wave transmission and overtopping around nearshore breakwaters can have significant influence on the transmitted wave parameters,which affects wave conditions and sediment transportation and becomes the focus of design in engineering.The objective of this paper is to present a simplified model to estimate these important wave parameters.This paper describes the incorporation of wave transmission and overtopping module into a wave model for multi-directional random wave transformation based on energy balance equation with the consideration of wave shoaling,refraction,diffraction,reflection and breaking.Wen's frequency spectrum and non-linear dispersion relation are also included in this model.The influence of wave parameters of transmitted waves through a smooth submerged breakwater has been considered in this model with an improved description of the transmitted wave spectrum of van der Meer et al.(2000) by Carevic et al.(2013).This improved wave model has been validated through available laboratory experiments.Then the verified model is applied to investigate the effect of wave transmission and overtopping on wave heights behind low-crested breakwaters in a project for nearshore area.Numerical calculations are carried out with and without consideration of the wave transmission and overtopping,and comparison of them indicates that there is a considerable difference in wave height and thus it is important to include wave transmission and overtopping in modelling nearshore wave field with the presence of low-crested breakwaters.Therefore,this model can provide a general estimate of the desired wave field parameters,which is adequate for engineers at the preliminary design stage of low-crested breakwaters.展开更多
An offshore platform of jacket type in Bohai Bay vibrated excessively under design environmental conditions, which had affected the normal operation of the platform. In order to mitigate the vibration of the platform,...An offshore platform of jacket type in Bohai Bay vibrated excessively under design environmental conditions, which had affected the normal operation of the platform. In order to mitigate the vibration of the platform, it is essentially important to explore the cause of the vibration. So the objective of this study is to investigate the cause of the excessive vibration. In this paper, dynamic characteristics of the offshore platform is analyzed by numerical simulation using finite element (FE) modeling. For further verifying the numerical results, model experiment is conducted. Numerical and experimental results demonstrate that there is relative movement and impact between the piles and the jacket, i.e. the piles and the jacket didnt connect well to an entity. It is this cause that the stiffness of the platform decreases and the impact between piles and the jacket legs induces excessive vibration. And also the grouting measure is advised to reduce the vibration of the offshore platform according to the analysis results.展开更多
We propose a method to establish a dynamic model for a wave glider, a wave-propelled sea surface vehicle that can make use of wave energy to obtain thrust. The vehicle, composed of a surface float and a submerged glid...We propose a method to establish a dynamic model for a wave glider, a wave-propelled sea surface vehicle that can make use of wave energy to obtain thrust. The vehicle, composed of a surface float and a submerged glider in sea water, is regarded as a two-particle system. Kane's equations are used to establish the dynamic model. To verify the model, the design of a testing prototype is proposed and pool trials are conducted. The speeds of the vehicle under different sea conditions can be computed using the model, which is verified by pool trials. The optimal structure parameters useful for vehicle designs can also be obtained from the model. We illustrate how to build an analytical dynamics model for the wave glider, which is a crucial basis for the vehicle's motion control. The dynamics model also provides foundations for an off-line simulation of vehicle performance and the optimization of its mechanical designs.展开更多
Slip boundary condition is commonly utilized to model elastic wave propagation through layered earth media. The same approach is used here to characterize acoustic wave propagation along a cased borehole with various ...Slip boundary condition is commonly utilized to model elastic wave propagation through layered earth media. The same approach is used here to characterize acoustic wave propagation along a cased borehole with various cement bond conditions. By modeling the cement layer between casing and formation as a viscoelastic slip interface with complex coupling rigidity parameters, one can not only reduce the complexity in the classical elastic wave modeling of the problem, but also efficiently model various complicated wave phenomena that are difficult for the existing modeling. More specifically, the new theory can well describe the effect of the cement bond condition change and the location of the change(i.e., whether it is in the first interface between casing and cement, or the second interface between cement and formation) on the acoustic waves,demonstrating the good modeling capability and predicting power. Application of the theory to field data shows that the theory can correctly model the acoustic wave characteristics and interpret the cement bond condition, thus providing a useful fundament theory for casing bond evaluation using acoustic logging.展开更多
文摘A new wave modeling method and a level of detail (LOD) scheme are proposed for ocean surface simulation in this paper.The modeling method describes ocean wave by modifying the sine wave,and gets wave direction at any position of ocean surface under any ocean floor conditions using wave num decomposition.LOD scheme is proposed based on quad-tree block,which simplifies the ocean surface regular mesh and realizes the real-time rendering of large-scale ocean surface.Experimental results show that these methods can get realistic effect and fast rendering speed,which are appropriated to the applications of 3D games and battlefield simulation.
基金supported by the NSFC-Shandong Joint Fund Project(No.U1706226)Research Award Fund for Outstanding Young and Middle-aged Scientists of Shandong Province(No.ZR2016EEB06)the Scientific Research Foundation of Shandong University of Science and Technology for Recruited Talents
文摘Wave transmission and overtopping around nearshore breakwaters can have significant influence on the transmitted wave parameters,which affects wave conditions and sediment transportation and becomes the focus of design in engineering.The objective of this paper is to present a simplified model to estimate these important wave parameters.This paper describes the incorporation of wave transmission and overtopping module into a wave model for multi-directional random wave transformation based on energy balance equation with the consideration of wave shoaling,refraction,diffraction,reflection and breaking.Wen's frequency spectrum and non-linear dispersion relation are also included in this model.The influence of wave parameters of transmitted waves through a smooth submerged breakwater has been considered in this model with an improved description of the transmitted wave spectrum of van der Meer et al.(2000) by Carevic et al.(2013).This improved wave model has been validated through available laboratory experiments.Then the verified model is applied to investigate the effect of wave transmission and overtopping on wave heights behind low-crested breakwaters in a project for nearshore area.Numerical calculations are carried out with and without consideration of the wave transmission and overtopping,and comparison of them indicates that there is a considerable difference in wave height and thus it is important to include wave transmission and overtopping in modelling nearshore wave field with the presence of low-crested breakwaters.Therefore,this model can provide a general estimate of the desired wave field parameters,which is adequate for engineers at the preliminary design stage of low-crested breakwaters.
文摘An offshore platform of jacket type in Bohai Bay vibrated excessively under design environmental conditions, which had affected the normal operation of the platform. In order to mitigate the vibration of the platform, it is essentially important to explore the cause of the vibration. So the objective of this study is to investigate the cause of the excessive vibration. In this paper, dynamic characteristics of the offshore platform is analyzed by numerical simulation using finite element (FE) modeling. For further verifying the numerical results, model experiment is conducted. Numerical and experimental results demonstrate that there is relative movement and impact between the piles and the jacket, i.e. the piles and the jacket didnt connect well to an entity. It is this cause that the stiffness of the platform decreases and the impact between piles and the jacket legs induces excessive vibration. And also the grouting measure is advised to reduce the vibration of the offshore platform according to the analysis results.
基金Project supported by the National Natural Science Foundation of China (Nos. 51305396 and U1509210) and the Fundamental Research Funds for the Central Universities, China
文摘We propose a method to establish a dynamic model for a wave glider, a wave-propelled sea surface vehicle that can make use of wave energy to obtain thrust. The vehicle, composed of a surface float and a submerged glider in sea water, is regarded as a two-particle system. Kane's equations are used to establish the dynamic model. To verify the model, the design of a testing prototype is proposed and pool trials are conducted. The speeds of the vehicle under different sea conditions can be computed using the model, which is verified by pool trials. The optimal structure parameters useful for vehicle designs can also be obtained from the model. We illustrate how to build an analytical dynamics model for the wave glider, which is a crucial basis for the vehicle's motion control. The dynamics model also provides foundations for an off-line simulation of vehicle performance and the optimization of its mechanical designs.
基金supported by the National Natural Science Foundation of China (Grant No. 41774141)
文摘Slip boundary condition is commonly utilized to model elastic wave propagation through layered earth media. The same approach is used here to characterize acoustic wave propagation along a cased borehole with various cement bond conditions. By modeling the cement layer between casing and formation as a viscoelastic slip interface with complex coupling rigidity parameters, one can not only reduce the complexity in the classical elastic wave modeling of the problem, but also efficiently model various complicated wave phenomena that are difficult for the existing modeling. More specifically, the new theory can well describe the effect of the cement bond condition change and the location of the change(i.e., whether it is in the first interface between casing and cement, or the second interface between cement and formation) on the acoustic waves,demonstrating the good modeling capability and predicting power. Application of the theory to field data shows that the theory can correctly model the acoustic wave characteristics and interpret the cement bond condition, thus providing a useful fundament theory for casing bond evaluation using acoustic logging.