该文采用课题组自主研发的CIP-ZJU(constraint interpolation profile model in Zhejiang University)模型对涌潮问题进行小尺度数值模拟研究。模型以高阶差分CIP方法为流场基本求解器,离散了纳维-斯托克斯(Navier-Stokes:N-S)方程,采用...该文采用课题组自主研发的CIP-ZJU(constraint interpolation profile model in Zhejiang University)模型对涌潮问题进行小尺度数值模拟研究。模型以高阶差分CIP方法为流场基本求解器,离散了纳维-斯托克斯(Navier-Stokes:N-S)方程,采用VOF(Volume of Fluid)类型的具有高精度、紧致的THINC(tangent of hyperbola for interface capturing)方法重构了自由水面。首先对经典溃坝问题开展了模型验证工作,通过与文献实验结果的比较验证模型的有效性;然后将模型应用于涌潮问题的相关研究,重点关注回头潮和水位变化过程,并得到相关规律和结论。该文的工作可丰富涌潮的小尺度数值模型,并可进一步拓宽CIP-ZJU模型的应用领域。展开更多
In this study, solitary waves passing over a submerged breakwater are investigated both experimentally and numerically. A total of 9 experimental conditions are carried out, including different incident wave heights a...In this study, solitary waves passing over a submerged breakwater are investigated both experimentally and numerically. A total of 9 experimental conditions are carried out, including different incident wave heights and water depths. Numerical simulations are performed using a high-order finite-difference model solving Navier–Stokes (N–S) equations. The predicted water wave elevation, velocity and pressure show good agreement with experimental data, verifying the accuracy and capacity of the numerical model. Furthermore, parametric studies are conducted by numerical modelling to examine the effects of the geometrical features of submerged dike on hydrodynamic characteristics around the breakwater.展开更多
利用自主研发的CIP-ZJU(Constrained Interpolation Profile Method in Zhejiang University)高精度数学模型研究强非线性自由表面流动问题.模型在直角坐标系统下建立,采用紧致插值曲线CIP方法作为流场的基本求解器,通过多相流的方式实...利用自主研发的CIP-ZJU(Constrained Interpolation Profile Method in Zhejiang University)高精度数学模型研究强非线性自由表面流动问题.模型在直角坐标系统下建立,采用紧致插值曲线CIP方法作为流场的基本求解器,通过多相流的方式实现固-液-气耦合同步求解,采用平衡格式的VOF(VOF/WLIC:Volume of Fluid/Weighted Line Interface Calculation)自由面捕捉方法改进了原模型,利用浸入边界方法处理运动物体.利用改进的CIP模型开展了不同类型的物体冲击液面引起的液滴飞溅现象的数值模拟,重点分析液滴飞溅过程中的自由液面变形、作用荷载和物体位置等.通过数值结果与实验结果的比较验证模型的可靠性.结果表明:平衡格式的VOF自由面捕捉方法能更精确地重构自由面,本文的数学模型可精确预测强非线性自由表面流动问题.展开更多
In this paper, two novel numerical computation methods are introduced which have been recently developed at Research Institute for Applied Mechanics （ R/AM ）, Kyushu University, for strongly nonlinear wave-body inte...In this paper, two novel numerical computation methods are introduced which have been recently developed at Research Institute for Applied Mechanics （ R/AM ）, Kyushu University, for strongly nonlinear wave-body interaction problems, such as ship motions in rough seas and resulting green-water impact on deck. The first method is the CIP-based Cartesian grid method, in which the free surface flow is treated as a multi-phase flow which is solved using a Cartesian grid. The second method is the MPS method, which is a so-called particle method and hence no grid is used. The features and calculation procedures of these numerical methods are described. One validation computation against a newly conducted experiment on a dam break problem, which is also described in this paper, is presented.展开更多
The flow past an in-line forced oscillating square cylinder at Reynolds number of 200 is studied using an in-house code, named constrained interpolation profile method developed in Zhejiang University （CIP-ZJU）. The...The flow past an in-line forced oscillating square cylinder at Reynolds number of 200 is studied using an in-house code, named constrained interpolation profile method developed in Zhejiang University （CIP-ZJU）. The model is established in the Cartesian coordinate system using the CIP method to discretise the Navier-Stokes equations. The fluid-structure interaction is treated as a multiphase flow of the liquid and solid phases to be solved simultaneously. An immersed boundary method is used to deal with the boundary of the solid body. The CFD model is first applied to the computation of the flow past a fixed square cylinder for its validation. Computations are then performed for the flow past a square cylinder oscillating in the streamwise direction. Considerable attention is paid to the symmetric and anti-symmetric modes of the vortex shedding in the oscillating square cylinder wake. Various oscillation amplitudes and frequencies are simulated and their effects on the vortex shedding modes are analyzed via Lissajous patterns of the unsteady lift coefficient. The relationship among the lift coefficient, the drag coefficient and the lock-on range is also investigated quantitatively.展开更多
An enhanced numerical model for simulating two-dimensional incompressible viscous flow with distorted free surface is reported. The numerical simulation is carried out through the CIP （Constrained Interpolation Prof...An enhanced numerical model for simulating two-dimensional incompressible viscous flow with distorted free surface is reported. The numerical simulation is carried out through the CIP （Constrained Interpolation Profile）-based method, which is described in the paper. A more accurate interface capturing scheme, the VOF/WLIC scheme （VOF：Volume-of-Fluid;WLIC：weighed line interface calculation）, is adopted as the interface capturing method. To assess the developed algorithm and its versatility, a selection of test problems are examined, i.e. the square wave propagation, the Zalesak’s rigid body rotation, dam breaking problem with and without obstacles, wave sloshing in an excited wave tank and interaction between extreme waves and a floating body. Excellent agreements are obtained when numerical results are compared with available analytical, experimental, and other numerical results. These examples demonstrate that the use of the VOF/WLIC scheme in the free surface capturing makes better results and also the proposed CIP-based model is capable of predicting the freak wave-related phenomena.展开更多
Laboratory experiments are performed to investigate the hydrodynamics around a submerged breakwater due to regular incident waves. With an in-house code, a constrained interpolation profile (CIP)-based model is employ...Laboratory experiments are performed to investigate the hydrodynamics around a submerged breakwater due to regular incident waves. With an in-house code, a constrained interpolation profile (CIP)-based model is employed to simulate this process. The model is built on a Cartesian grid system with the Navier-Stokes equations using a CIP method for the flow solver and an immersed boundary method (IBM) is used for the treatment of the solid body boundary. A more accurate interface capturing scheme, the tangent of hyperbola for interface capturing/slope weighting (THINC/SW) scheme, is used to track the free surface. The numerical results are compared with experimental data. Reasonably good agreement is achieved in terms of the wave profiles at six measuring stations, the flow velocities at three different space locations and the pressures of eight points on the surface of the submerged breakwater. Moreover, the water mass transfer over the breakwater is discussed using a two-phase VOF model and the wave spectrum is also presented for analysis. It is indicated that the present model can accurately predict the hydrodynamic characteristics of the wave over a submerged bar. Furthermore, the experimental data in the present work can provide reliable basic data, including the wave transformations, the velocities and the dynamic pressures, for the validation of other CFD models.展开更多
Floating structures are commonly seen in coastal and offshore engineering. They are often subjected to extreme waves and, therefore, their nonlinear dynamic behaviors are of great concern. In this paper, an in-house C...Floating structures are commonly seen in coastal and offshore engineering. They are often subjected to extreme waves and, therefore, their nonlinear dynamic behaviors are of great concern. In this paper, an in-house CFD code is developed to investigate the accurate prediction of nonlinear dynamic behaviors of a two-dimensional（2-D） box-shaped floating structure in focused waves. Computations are performed by an enhanced Constrained Interpolation Profile（CIP）-based Cartesian grid model, in which a more accurate VOF（Volume of Fluid） method, the THINC/SW scheme（THINC： tangent of hyperbola for interface capturing; SW： Slope Weighting）, is used for interface capturing. A focusing wave theory is used for the focused wave generation. The wave component of constant steepness is chosen. Comparisons between predictions and physical measurements show good agreement including body motions and free surface profiles. Although the overall agreement is good, some discrepancies are observed for impact pressure on the superstructure due to water on deck. The effect of grid resolution on the results is checked. With a fine grid, no obvious improvement is seen in the global body motions and impact pressures due to water on deck. It is concluded that highly nonlinear phenomena, such as distorted free surface, large-amplitude body motions, and violent impact flow, have been predicted successfully.展开更多
We present a Cartesian grid method for numerical simulation of strongly nonlinear phenomena of ship-wave interactions. The Constraint Interpolation Profile （CIP） method is applied to the flow solver, which can effic...We present a Cartesian grid method for numerical simulation of strongly nonlinear phenomena of ship-wave interactions. The Constraint Interpolation Profile （CIP） method is applied to the flow solver, which can efficiently increase the discretization accuracy on the moving boundaries for the Cartesian grid method. Tangent of Hyperbola for Interface Capturing （THINC） is imple- mented as an interface capturing scheme for free surface calculation. An improved immersed boundary method is developed to treat moving bodies with complex-shaped geometries. In this paper, the main features and some recent improvements of the Cartesian grid method are described and several numerical simulation results are presented to discuss its performance.展开更多
文摘该文采用课题组自主研发的CIP-ZJU(constraint interpolation profile model in Zhejiang University)模型对涌潮问题进行小尺度数值模拟研究。模型以高阶差分CIP方法为流场基本求解器,离散了纳维-斯托克斯(Navier-Stokes:N-S)方程,采用VOF(Volume of Fluid)类型的具有高精度、紧致的THINC(tangent of hyperbola for interface capturing)方法重构了自由水面。首先对经典溃坝问题开展了模型验证工作,通过与文献实验结果的比较验证模型的有效性;然后将模型应用于涌潮问题的相关研究,重点关注回头潮和水位变化过程,并得到相关规律和结论。该文的工作可丰富涌潮的小尺度数值模型,并可进一步拓宽CIP-ZJU模型的应用领域。
基金financially supported by the National Natural Science Foundation of China(Grant No.51679212)Zhejiang Provincial Natural Science Foundation of China(Grant No.LR16E090002)+1 种基金the Fundamental Research Funds for the Central Universities(Grant No.2018QNA4041)the Tang Scholar
文摘In this study, solitary waves passing over a submerged breakwater are investigated both experimentally and numerically. A total of 9 experimental conditions are carried out, including different incident wave heights and water depths. Numerical simulations are performed using a high-order finite-difference model solving Navier–Stokes (N–S) equations. The predicted water wave elevation, velocity and pressure show good agreement with experimental data, verifying the accuracy and capacity of the numerical model. Furthermore, parametric studies are conducted by numerical modelling to examine the effects of the geometrical features of submerged dike on hydrodynamic characteristics around the breakwater.
文摘利用自主研发的CIP-ZJU(Constrained Interpolation Profile Method in Zhejiang University)高精度数学模型研究强非线性自由表面流动问题.模型在直角坐标系统下建立,采用紧致插值曲线CIP方法作为流场的基本求解器,通过多相流的方式实现固-液-气耦合同步求解,采用平衡格式的VOF(VOF/WLIC:Volume of Fluid/Weighted Line Interface Calculation)自由面捕捉方法改进了原模型,利用浸入边界方法处理运动物体.利用改进的CIP模型开展了不同类型的物体冲击液面引起的液滴飞溅现象的数值模拟,重点分析液滴飞溅过程中的自由液面变形、作用荷载和物体位置等.通过数值结果与实验结果的比较验证模型的可靠性.结果表明:平衡格式的VOF自由面捕捉方法能更精确地重构自由面,本文的数学模型可精确预测强非线性自由表面流动问题.
文摘In this paper, two novel numerical computation methods are introduced which have been recently developed at Research Institute for Applied Mechanics （ R/AM ）, Kyushu University, for strongly nonlinear wave-body interaction problems, such as ship motions in rough seas and resulting green-water impact on deck. The first method is the CIP-based Cartesian grid method, in which the free surface flow is treated as a multi-phase flow which is solved using a Cartesian grid. The second method is the MPS method, which is a so-called particle method and hence no grid is used. The features and calculation procedures of these numerical methods are described. One validation computation against a newly conducted experiment on a dam break problem, which is also described in this paper, is presented.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51209184,51479175 and 51679212)the Natural Science Foundation of Zhejiang Province(Grant No.LR16E090002)
文摘The flow past an in-line forced oscillating square cylinder at Reynolds number of 200 is studied using an in-house code, named constrained interpolation profile method developed in Zhejiang University （CIP-ZJU）. The model is established in the Cartesian coordinate system using the CIP method to discretise the Navier-Stokes equations. The fluid-structure interaction is treated as a multiphase flow of the liquid and solid phases to be solved simultaneously. An immersed boundary method is used to deal with the boundary of the solid body. The CFD model is first applied to the computation of the flow past a fixed square cylinder for its validation. Computations are then performed for the flow past a square cylinder oscillating in the streamwise direction. Considerable attention is paid to the symmetric and anti-symmetric modes of the vortex shedding in the oscillating square cylinder wake. Various oscillation amplitudes and frequencies are simulated and their effects on the vortex shedding modes are analyzed via Lissajous patterns of the unsteady lift coefficient. The relationship among the lift coefficient, the drag coefficient and the lock-on range is also investigated quantitatively.
基金financially supported by the National Natural Science Foundation of China(Grant No.51209184)the Fundamental Research Funds for the Central Universities(Grant No.2012QNA4020)+1 种基金the Zhejiang Open Foundation of the Most Important Subjects,the Key Laboratory of Water-Sediment Sciences and Water Disaster Prevention of Hunan Province(Grant No.2013SS03)the Educational Commission of Zhejiang Province of China(Grant No.Y201225713)
文摘An enhanced numerical model for simulating two-dimensional incompressible viscous flow with distorted free surface is reported. The numerical simulation is carried out through the CIP （Constrained Interpolation Profile）-based method, which is described in the paper. A more accurate interface capturing scheme, the VOF/WLIC scheme （VOF：Volume-of-Fluid;WLIC：weighed line interface calculation）, is adopted as the interface capturing method. To assess the developed algorithm and its versatility, a selection of test problems are examined, i.e. the square wave propagation, the Zalesak’s rigid body rotation, dam breaking problem with and without obstacles, wave sloshing in an excited wave tank and interaction between extreme waves and a floating body. Excellent agreements are obtained when numerical results are compared with available analytical, experimental, and other numerical results. These examples demonstrate that the use of the VOF/WLIC scheme in the free surface capturing makes better results and also the proposed CIP-based model is capable of predicting the freak wave-related phenomena.
基金Project supported by the National Natural Science Foundation of China (Grant No. 51679212)the Natural Science Foundation of Zhejiang Province (Grant No. LR16E090002)the Fundamental Research Funds for the Central Universities (Grant No. 2018QNA4041).
文摘Laboratory experiments are performed to investigate the hydrodynamics around a submerged breakwater due to regular incident waves. With an in-house code, a constrained interpolation profile (CIP)-based model is employed to simulate this process. The model is built on a Cartesian grid system with the Navier-Stokes equations using a CIP method for the flow solver and an immersed boundary method (IBM) is used for the treatment of the solid body boundary. A more accurate interface capturing scheme, the tangent of hyperbola for interface capturing/slope weighting (THINC/SW) scheme, is used to track the free surface. The numerical results are compared with experimental data. Reasonably good agreement is achieved in terms of the wave profiles at six measuring stations, the flow velocities at three different space locations and the pressures of eight points on the surface of the submerged breakwater. Moreover, the water mass transfer over the breakwater is discussed using a two-phase VOF model and the wave spectrum is also presented for analysis. It is indicated that the present model can accurately predict the hydrodynamic characteristics of the wave over a submerged bar. Furthermore, the experimental data in the present work can provide reliable basic data, including the wave transformations, the velocities and the dynamic pressures, for the validation of other CFD models.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.51209184 and 51479175)Zhejiang Provincial Natural Science Foundation of China(Grant No.LR16E090002)the Open Foundation of State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering(Grant No.2013490211)
文摘Floating structures are commonly seen in coastal and offshore engineering. They are often subjected to extreme waves and, therefore, their nonlinear dynamic behaviors are of great concern. In this paper, an in-house CFD code is developed to investigate the accurate prediction of nonlinear dynamic behaviors of a two-dimensional（2-D） box-shaped floating structure in focused waves. Computations are performed by an enhanced Constrained Interpolation Profile（CIP）-based Cartesian grid model, in which a more accurate VOF（Volume of Fluid） method, the THINC/SW scheme（THINC： tangent of hyperbola for interface capturing; SW： Slope Weighting）, is used for interface capturing. A focusing wave theory is used for the focused wave generation. The wave component of constant steepness is chosen. Comparisons between predictions and physical measurements show good agreement including body motions and free surface profiles. Although the overall agreement is good, some discrepancies are observed for impact pressure on the superstructure due to water on deck. The effect of grid resolution on the results is checked. With a fine grid, no obvious improvement is seen in the global body motions and impact pressures due to water on deck. It is concluded that highly nonlinear phenomena, such as distorted free surface, large-amplitude body motions, and violent impact flow, have been predicted successfully.
文摘We present a Cartesian grid method for numerical simulation of strongly nonlinear phenomena of ship-wave interactions. The Constraint Interpolation Profile （CIP） method is applied to the flow solver, which can efficiently increase the discretization accuracy on the moving boundaries for the Cartesian grid method. Tangent of Hyperbola for Interface Capturing （THINC） is imple- mented as an interface capturing scheme for free surface calculation. An improved immersed boundary method is developed to treat moving bodies with complex-shaped geometries. In this paper, the main features and some recent improvements of the Cartesian grid method are described and several numerical simulation results are presented to discuss its performance.
