Rubble mound breakwaters with a crown wall are a common coastal engineering structure.The wave force on crown walls is an important parameter for the practice engineering design.Particularly,the wave force on crown wa...Rubble mound breakwaters with a crown wall are a common coastal engineering structure.The wave force on crown walls is an important parameter for the practice engineering design.Particularly,the wave force on crown walls under intermediate depths has been studied through physical model tests and numerical simulations.In this study,a three-dimensional numerical wave flume was developed to investigate monochromatic wave interactions in a rubble mound breakwater with a crown wall.Armor blocks were modeled in detail.The Navier-Stokes equations for two-phase incompressible flows,combined with shear stress transport k-ωturbulence model and volume of fluid method for tracking the free surface,were solved.A set of laboratory experiments were performed to validate the adopted model.Subsequently,a series of numerical simulations were implemented to examine the impacts of different hydrodynamic parameters(including wave height,incident wave period,and water depth)and the berm width on the wave force of the crown wall.Finally,a comparison of the experimental results and Martin method shows that the latter method is not suitable for this experimental scope.New empirical formulas are proposed to predict the wave force on crown walls under intermediate depth.The results can provide a basis for the design of crown wall of rubble mound breakwaters at intermediate depths.展开更多
In the present study, a new algorithm based on the Volume Of Fluid （VOF） method is developed to simulate the hydrodynamic characteristics on an arc crown wall. Structured grids are generated by the coordinate transf...In the present study, a new algorithm based on the Volume Of Fluid （VOF） method is developed to simulate the hydrodynamic characteristics on an arc crown wall. Structured grids are generated by the coordinate transform method in an arbitrary complex region. The Navier-Stokes equations for two-dimensional incompressible viscous flows are discretized in the Body Fitted Coordinate （BFC） system. The transformed SIMPLE algorithm is proposed to modify the pressure-velocity field and a transformed VOF method is used to trace the free surface. Hydrodynamic characteristics on an arc crown wall are obtained by the improved numerical model based on the BFC system （BFC model）. The velocity field, the pressure field and the time profiles of the water surface near the arc crown wall obtained by using the BFC model and the Cartesian model are compared. The BFC model is verified by experimental results.展开更多
Cylinder-crown integrated hydraulic press( CCIHP) is a new press structure. The hemispherical hydraulic cylinder also functions as a main portion of crown,which has lower weight and higher section modulus compared wit...Cylinder-crown integrated hydraulic press( CCIHP) is a new press structure. The hemispherical hydraulic cylinder also functions as a main portion of crown,which has lower weight and higher section modulus compared with the conventional hydraulic cylinder and press crown. In order to design cylinder-crown integrated hydraulic press with large capacity, the theoretical design of hemispherical hydraulic cylinder was first proposed,and the structural parameters of 150 MN CCIHP were listed. Then the simulation was carried out to analyze the stress and deformation of CCIHP,and weight comparison was conducted between CCIHP and conventional press. It is shown that the weight reduction for hydraulic cylinder and press crown is about 20% compared with that for conventional press,and the stress and deformation are both within the range of constraints including strength and stiffness conditions. It is possible to manufacture cylinder-crown integrated hydraulic press with large capacity.展开更多
针对笛卡尔坐标系下的VOF(volume of fluid)方法无法精确模拟复杂边界的自由表面流动问题,以连续方程和雷诺平均方程为基本控制方程,采用k-ε湍流模型来封闭方程组,修正了基于交错网格的贴体坐标系下的SIMPLE算法来迭代求解压力-速度场...针对笛卡尔坐标系下的VOF(volume of fluid)方法无法精确模拟复杂边界的自由表面流动问题,以连续方程和雷诺平均方程为基本控制方程,采用k-ε湍流模型来封闭方程组,修正了基于交错网格的贴体坐标系下的SIMPLE算法来迭代求解压力-速度场,修正了贴体坐标系下的界面跟踪方法,建立了基于BFC-VOF方法求解波浪对弧形胸墙结构作用的数值计算模型.对弧形胸墙结构附近的波面、流场及其所受波浪力等进行了数值模拟.研究结果表明:贴体网格模型能够精确模拟复杂边界的自由表面流动问题,模型计算的弧形胸墙迎浪面所受到的波浪力随着圆弧半径的增大而减小.展开更多
基金supported by the National Natural Science Foundation of China–Shandong Joint Fund(No.U1706226)the National Natural Science Foundation of China(No.52171284).
文摘Rubble mound breakwaters with a crown wall are a common coastal engineering structure.The wave force on crown walls is an important parameter for the practice engineering design.Particularly,the wave force on crown walls under intermediate depths has been studied through physical model tests and numerical simulations.In this study,a three-dimensional numerical wave flume was developed to investigate monochromatic wave interactions in a rubble mound breakwater with a crown wall.Armor blocks were modeled in detail.The Navier-Stokes equations for two-phase incompressible flows,combined with shear stress transport k-ωturbulence model and volume of fluid method for tracking the free surface,were solved.A set of laboratory experiments were performed to validate the adopted model.Subsequently,a series of numerical simulations were implemented to examine the impacts of different hydrodynamic parameters(including wave height,incident wave period,and water depth)and the berm width on the wave force of the crown wall.Finally,a comparison of the experimental results and Martin method shows that the latter method is not suitable for this experimental scope.New empirical formulas are proposed to predict the wave force on crown walls under intermediate depth.The results can provide a basis for the design of crown wall of rubble mound breakwaters at intermediate depths.
基金supported by the National Natural Science Foundation of China (Grant Nos. 51179030, 50921001)
文摘In the present study, a new algorithm based on the Volume Of Fluid （VOF） method is developed to simulate the hydrodynamic characteristics on an arc crown wall. Structured grids are generated by the coordinate transform method in an arbitrary complex region. The Navier-Stokes equations for two-dimensional incompressible viscous flows are discretized in the Body Fitted Coordinate （BFC） system. The transformed SIMPLE algorithm is proposed to modify the pressure-velocity field and a transformed VOF method is used to trace the free surface. Hydrodynamic characteristics on an arc crown wall are obtained by the improved numerical model based on the BFC system （BFC model）. The velocity field, the pressure field and the time profiles of the water surface near the arc crown wall obtained by using the BFC model and the Cartesian model are compared. The BFC model is verified by experimental results.
基金Sponsored by the High-end CNC Machine Tools and Basic Manufacturing Equipment Technology Major Project(Grant No.2011ZX04001-011)
文摘Cylinder-crown integrated hydraulic press( CCIHP) is a new press structure. The hemispherical hydraulic cylinder also functions as a main portion of crown,which has lower weight and higher section modulus compared with the conventional hydraulic cylinder and press crown. In order to design cylinder-crown integrated hydraulic press with large capacity, the theoretical design of hemispherical hydraulic cylinder was first proposed,and the structural parameters of 150 MN CCIHP were listed. Then the simulation was carried out to analyze the stress and deformation of CCIHP,and weight comparison was conducted between CCIHP and conventional press. It is shown that the weight reduction for hydraulic cylinder and press crown is about 20% compared with that for conventional press,and the stress and deformation are both within the range of constraints including strength and stiffness conditions. It is possible to manufacture cylinder-crown integrated hydraulic press with large capacity.
文摘针对笛卡尔坐标系下的VOF(volume of fluid)方法无法精确模拟复杂边界的自由表面流动问题,以连续方程和雷诺平均方程为基本控制方程,采用k-ε湍流模型来封闭方程组,修正了基于交错网格的贴体坐标系下的SIMPLE算法来迭代求解压力-速度场,修正了贴体坐标系下的界面跟踪方法,建立了基于BFC-VOF方法求解波浪对弧形胸墙结构作用的数值计算模型.对弧形胸墙结构附近的波面、流场及其所受波浪力等进行了数值模拟.研究结果表明:贴体网格模型能够精确模拟复杂边界的自由表面流动问题,模型计算的弧形胸墙迎浪面所受到的波浪力随着圆弧半径的增大而减小.
