Complex factors including steep slopes, intense wave breaking, large bottom friction and remarkable wave setup should be considered while studying wave propagation over coral reefs, and how to simulate wave propagatio...Complex factors including steep slopes, intense wave breaking, large bottom friction and remarkable wave setup should be considered while studying wave propagation over coral reefs, and how to simulate wave propagation and setup on coral reefs efficiently has become a primary focus. Several wave models can be used on coral reefs as have been published, but further testing and comparison of the reliability and applicability of these models are needed. A comparative study of four numerical wave models (i.e., FUNWAVE-TVD, Coulwave, NHWAVE and ZZL18) is carried out in this paper. These models’ governing equations and numerical methods are compared and analyzed firstly to obtain their differences and connections;then the simulation effects of the four wave models are tested in four representative laboratory experiments. The results show that all four models can reasonably predict the spectrum transformation. Coulwave, NHWAVE and ZZL18 can predict the wave height variation more accurately;Coulwave and FUNWAVE-TVD tend to underestimate wave setup on the reef top induced by spilling breaker, while NHWAVE and ZZL18 can predict wave setup relatively accurately for all types of breakers;NHWAVE and ZZL18 can predict wave reflection by steep reef slope more accurately. This study can provide evidence for choosing suitable models for practical engineering or establishing new models.展开更多
In the course of the propagation of waves from the offshore to the nearshore zone, the wave may break due to the shoaling effect. Strong impact forces are observed when the breaking wave acts on the pier of the bridge...In the course of the propagation of waves from the offshore to the nearshore zone, the wave may break due to the shoaling effect. Strong impact forces are observed when the breaking wave acts on the pier of the bridge. This impact force might not only change the dynamic load pattern on the pier but also cause strong structural vibration, which may threaten the driving and structural safety of the bridge. Many studies have been carried out to study the issues in the aspect of wave flume experiment, numerical simulation, calculation of breaking wave force, and random vibration response of the structure. Considering the studies of breaking wave load on bridge piers are lack of systematic summaries, this paper presents a comprehensive and up-to-date literature review of breaking wave research and practice related to bridges. Firstly, a brief introduction is given, which includes recent cases of bridge failures caused by breaking waves. Then, both scientific and technical studies are reviewed, categorized into four aspects: experimental study, numerical simulation, analytical calculation of breaking wave force, and the structural response under breaking wave. Finally, Discussion is provided on four emerging ideas to investigate breaking wave forces on the pier from both science and engineering perspectives.展开更多
A novel numerical framework is developed for large-eddy simulation(LES) of interactions among air, water, and solid bodies. The motions of air and water are solved on a fixed block-structured mesh, with the air–water...A novel numerical framework is developed for large-eddy simulation(LES) of interactions among air, water, and solid bodies. The motions of air and water are solved on a fixed block-structured mesh, with the air–water interface captured using the volume-of-fluid method. A new sub-grid scale stress model based on the vortex identifier is used to improve the robustness and efficiency of the simulation flows with air–water interface. The new framework is tested in the context of bow waves and Kelvin waves generated by a water-surface vehicle. Wave breaking at the bow of the vehicle is captured in LES. The LES results of wave geometry approaches the measurements progressively as the grid resolution is refined. The simulation results indicate that LES is a useful tool for studying wave dynamics of water-surface vehicles.展开更多
Among all environmental forces acting on ocean structures and marine vessels, those resulting from wave impacts are likely to yield the highest loads. Being highly nonlinear, transient and complex, a theoretical analy...Among all environmental forces acting on ocean structures and marine vessels, those resulting from wave impacts are likely to yield the highest loads. Being highly nonlinear, transient and complex, a theoretical analysis of their impact would be impossible without numerical simulations. In this paper, a pressure-split two-stage numerical algorithm is proposed based on Volume Of Fluid （VOF） methodology. The algorithm is characterized by introduction of two pressures at each half and full cycle time step, and thus it is a second-order accurate algorithm in time. A simplified second-order Godunov-type solver is used for the continuity equations. The method is applied to simulation of breaking waves in a 2-D water tank, and a qualitative comparison with experimental photo observations is made. Quite consistent results are observed between simulations and experiments. Commercially available software and Boundary Integral Method （BIM） have also been used to simulate the same problem. The results from present code and BIM are in good agreement with respect to breaking location and timing, while the results obtained from the comrnercial software which is only first-order accurate in time has clearly showed a temporal and spatial lag, verifying the need to use a higher order numerical scheme.展开更多
Based on the time dependent mild slope equation including the effect of wave energy dissipation, an expression for the energy dissipation factor is derived in conjunction with the wave energy balance equation, and the...Based on the time dependent mild slope equation including the effect of wave energy dissipation, an expression for the energy dissipation factor is derived in conjunction with the wave energy balance equation, and then a practical method for the simulation of wave height and wave set- up in nearshore regions is presented. The variation of the complex wave amplitude is numerically simulated by use of the parabolic mild slope equation including the effect of wave energy dissipation due to wave breaking. The components of wave radiation stress are calculated subsequently by new expressions for them according to the obtained complex wave amplitude, and then the depth-averaged equation is applied to the calculation of wave set-up due to wave breaking. Numerical results are in good agreement with experimental data, showing that the expression for the energy dissipation factor is reasonable and that the new method is effective for the simulation of wave set-up due to wave breaking in nearshore regions.展开更多
The Large Eddy Simulation （LES） of the wave breaking over a muddy seabed is carried out with a Coupled Level Set and Volume Of Fluid （CLSVOF） method to capture the interfaces.The effects of the mud on the wave bre...The Large Eddy Simulation （LES） of the wave breaking over a muddy seabed is carried out with a Coupled Level Set and Volume Of Fluid （CLSVOF） method to capture the interfaces.The effects of the mud on the wave breaking are studied.The existence of a mud layer beneath an otherwise rigid bottom is found to have a similar effect as an increase of the water depth.As compared with the case of a simple rigid bottom,the inception of the wave breaking is evidently delayed and the breaking intensity is much reduced.The dissipation of the wave energy is shown to have very different rates before,during and after the breaking.Before and after the breaking,the mud plays an important role.During the breaking,however,the turbulence as well as the entrainment of the air also dissipate a large amount of energy.展开更多
As wave propagates into shallow water, the shoaling effect leads to increaseof wave height, and at a certain position, the wave will be breaking. The breaking wave is powerfulagents for generating turbulence, which pl...As wave propagates into shallow water, the shoaling effect leads to increaseof wave height, and at a certain position, the wave will be breaking. The breaking wave is powerfulagents for generating turbulence, which plays an important role in most of the fluid dynamicalprocesses in the surf zone, so a proper numerical model for describing the turbulent effect isneeded urgently. A numerical model is set up to simulate the wave breaking process, which consistsof a free surface model using the surface marker method and the vertical two-dimensional model thatsolves the flow equations. The turbulence is described by Large Eddy Simulation (LES) method wherethe larger turbulent features are simulated by solving the flow equations, and the small-scaleturbulence that is represented by a sub-grid model. A dynamic eddy viscosity sub-grid scale stressmodel has been used for the present simulation. The large eddy simulation model, which we presentedin this paper, can be used to study the propagation of a solitary wave in constant water depth andthe shoaling of a non-breaking solitary wave on a beach. To track free-surface movements, The TUMMACmethod is employed. By applying the model to wave breaking problem in the surf zone, we found thatthese model results compared very well with experimental data. In addition, this model is able toreproduce the complicated flow phenomena, especially the plunging breaker.展开更多
基金financially supported by the National Natural Science Foundation of China(Grant Nos.11572130 and 41106031)
文摘Complex factors including steep slopes, intense wave breaking, large bottom friction and remarkable wave setup should be considered while studying wave propagation over coral reefs, and how to simulate wave propagation and setup on coral reefs efficiently has become a primary focus. Several wave models can be used on coral reefs as have been published, but further testing and comparison of the reliability and applicability of these models are needed. A comparative study of four numerical wave models (i.e., FUNWAVE-TVD, Coulwave, NHWAVE and ZZL18) is carried out in this paper. These models’ governing equations and numerical methods are compared and analyzed firstly to obtain their differences and connections;then the simulation effects of the four wave models are tested in four representative laboratory experiments. The results show that all four models can reasonably predict the spectrum transformation. Coulwave, NHWAVE and ZZL18 can predict the wave height variation more accurately;Coulwave and FUNWAVE-TVD tend to underestimate wave setup on the reef top induced by spilling breaker, while NHWAVE and ZZL18 can predict wave setup relatively accurately for all types of breakers;NHWAVE and ZZL18 can predict wave reflection by steep reef slope more accurately. This study can provide evidence for choosing suitable models for practical engineering or establishing new models.
基金financial support from the National Natural Science Foundation of China(No.51978578)。
文摘In the course of the propagation of waves from the offshore to the nearshore zone, the wave may break due to the shoaling effect. Strong impact forces are observed when the breaking wave acts on the pier of the bridge. This impact force might not only change the dynamic load pattern on the pier but also cause strong structural vibration, which may threaten the driving and structural safety of the bridge. Many studies have been carried out to study the issues in the aspect of wave flume experiment, numerical simulation, calculation of breaking wave force, and random vibration response of the structure. Considering the studies of breaking wave load on bridge piers are lack of systematic summaries, this paper presents a comprehensive and up-to-date literature review of breaking wave research and practice related to bridges. Firstly, a brief introduction is given, which includes recent cases of bridge failures caused by breaking waves. Then, both scientific and technical studies are reviewed, categorized into four aspects: experimental study, numerical simulation, analytical calculation of breaking wave force, and the structural response under breaking wave. Finally, Discussion is provided on four emerging ideas to investigate breaking wave forces on the pier from both science and engineering perspectives.
基金supported by Lixing plan of Institute of Mechanics,Chinese Academy of Sciencesthe National Natural Science Foundation of China(91752119,11232011 and11572331)+1 种基金the support from the Strategic Priority Research Program(XDB22040104)the Key Research Program of Frontier Sciences of the Chinese Academy of Sciences(QYZDJ-SSW-SYS002)
文摘A novel numerical framework is developed for large-eddy simulation(LES) of interactions among air, water, and solid bodies. The motions of air and water are solved on a fixed block-structured mesh, with the air–water interface captured using the volume-of-fluid method. A new sub-grid scale stress model based on the vortex identifier is used to improve the robustness and efficiency of the simulation flows with air–water interface. The new framework is tested in the context of bow waves and Kelvin waves generated by a water-surface vehicle. Wave breaking at the bow of the vehicle is captured in LES. The LES results of wave geometry approaches the measurements progressively as the grid resolution is refined. The simulation results indicate that LES is a useful tool for studying wave dynamics of water-surface vehicles.
基金Supported by the National Natural Science Foundation of China under Grant Nos 50679010 and 50579004.
文摘Among all environmental forces acting on ocean structures and marine vessels, those resulting from wave impacts are likely to yield the highest loads. Being highly nonlinear, transient and complex, a theoretical analysis of their impact would be impossible without numerical simulations. In this paper, a pressure-split two-stage numerical algorithm is proposed based on Volume Of Fluid （VOF） methodology. The algorithm is characterized by introduction of two pressures at each half and full cycle time step, and thus it is a second-order accurate algorithm in time. A simplified second-order Godunov-type solver is used for the continuity equations. The method is applied to simulation of breaking waves in a 2-D water tank, and a qualitative comparison with experimental photo observations is made. Quite consistent results are observed between simulations and experiments. Commercially available software and Boundary Integral Method （BIM） have also been used to simulate the same problem. The results from present code and BIM are in good agreement with respect to breaking location and timing, while the results obtained from the comrnercial software which is only first-order accurate in time has clearly showed a temporal and spatial lag, verifying the need to use a higher order numerical scheme.
基金This subject was financially supported by the National Natural Science Foundation of China (Grant No. 59839330 and No. 59979025)
文摘Based on the time dependent mild slope equation including the effect of wave energy dissipation, an expression for the energy dissipation factor is derived in conjunction with the wave energy balance equation, and then a practical method for the simulation of wave height and wave set- up in nearshore regions is presented. The variation of the complex wave amplitude is numerically simulated by use of the parabolic mild slope equation including the effect of wave energy dissipation due to wave breaking. The components of wave radiation stress are calculated subsequently by new expressions for them according to the obtained complex wave amplitude, and then the depth-averaged equation is applied to the calculation of wave set-up due to wave breaking. Numerical results are in good agreement with experimental data, showing that the expression for the energy dissipation factor is reasonable and that the new method is effective for the simulation of wave set-up due to wave breaking in nearshore regions.
基金Project supported by the National Natural Science Foundation of China (Grant No.51109119)the State key Laboratory of Hydro-science and Engineering,Tsinghua University (Grant No.2011-KY-1)
文摘The Large Eddy Simulation （LES） of the wave breaking over a muddy seabed is carried out with a Coupled Level Set and Volume Of Fluid （CLSVOF） method to capture the interfaces.The effects of the mud on the wave breaking are studied.The existence of a mud layer beneath an otherwise rigid bottom is found to have a similar effect as an increase of the water depth.As compared with the case of a simple rigid bottom,the inception of the wave breaking is evidently delayed and the breaking intensity is much reduced.The dissipation of the wave energy is shown to have very different rates before,during and after the breaking.Before and after the breaking,the mud plays an important role.During the breaking,however,the turbulence as well as the entrainment of the air also dissipate a large amount of energy.
文摘As wave propagates into shallow water, the shoaling effect leads to increaseof wave height, and at a certain position, the wave will be breaking. The breaking wave is powerfulagents for generating turbulence, which plays an important role in most of the fluid dynamicalprocesses in the surf zone, so a proper numerical model for describing the turbulent effect isneeded urgently. A numerical model is set up to simulate the wave breaking process, which consistsof a free surface model using the surface marker method and the vertical two-dimensional model thatsolves the flow equations. The turbulence is described by Large Eddy Simulation (LES) method wherethe larger turbulent features are simulated by solving the flow equations, and the small-scaleturbulence that is represented by a sub-grid model. A dynamic eddy viscosity sub-grid scale stressmodel has been used for the present simulation. The large eddy simulation model, which we presentedin this paper, can be used to study the propagation of a solitary wave in constant water depth andthe shoaling of a non-breaking solitary wave on a beach. To track free-surface movements, The TUMMACmethod is employed. By applying the model to wave breaking problem in the surf zone, we found thatthese model results compared very well with experimental data. In addition, this model is able toreproduce the complicated flow phenomena, especially the plunging breaker.
