A nonlinear Schrodinger equation in one-dimensional bead chain is first obtained and an envelope solitary wave of the system is verified numerically in this system. The reflection and the transmission of an incident e...A nonlinear Schrodinger equation in one-dimensional bead chain is first obtained and an envelope solitary wave of the system is verified numerically in this system. The reflection and the transmission of an incident envelope solitary wave due to impurities has also been investigated. It is found that the magnitudes of both the reflection and the transmission not only depend on the characters of impurity materials, the wave number, the incident wave amplitude, but also on the impurity number. This can be used to detect the character and the number of the impurity materials in the bead chain by measuring the reflection and the transmission of an incident pulse.展开更多
Reflections of a Korteweg-de Vries (KdV) solitary wave and an envelope solitary wave are studied by using the particle-in-cell simulation method. Defining the phase shift of the reflected solitary wave, we notice th...Reflections of a Korteweg-de Vries (KdV) solitary wave and an envelope solitary wave are studied by using the particle-in-cell simulation method. Defining the phase shift of the reflected solitary wave, we notice that there is a phase shift of the reflected KdV solitary wave, while there is no phase shift for an envelope solitary wave. It is also noted that the reflection of a KdV solitary wave at a solid boundary is equivalent to the head-on collision between two identical amplitude solitary waves.展开更多
Wave forces acting on a vertical cylinder at different locations on a slope beach in the near-shore region are investigated considering solitary waves as incoming waves.Based on the Reynolds-averaged Navier-Stokes equ...Wave forces acting on a vertical cylinder at different locations on a slope beach in the near-shore region are investigated considering solitary waves as incoming waves.Based on the Reynolds-averaged Navier-Stokes equations and the k-ε turbulence model,wave forces due to the interaction between the solitary wave and cylinder are simulated and analyzed with different incident wave heights and cylinder locations.The numerical results are first compared with previous theoretical and experimental results to validate the model accuracy.Then,the wave forces and characteristics around the cylinder are studied,including the velocity field,wave surface elevation and pressure.The effects of relative wave height,Keulegan-Carpenter(KC)number and cylinder locations on the wave forces are also discussed.The results show that the wave forces exerted on a cylinder exponentially increase with the increasing incident wave height and KC number.Before the wave force peaks,the growth rate of the wave force shows an increasing trend as the cylinder moves onshore.The cylinder location has a notable effect on the wave force on the cylinder in the near-shore region.As the cylinder moves onshore,the wave force on the cylinder initially increases and then decreases.For the cases considered here,the maximum wave force appears when the cylinder is located one cylinder diameter below the still-water shoreline.Furthermore,the fluid velocity peaks when the maximum wave force appears at the same location.展开更多
Scale effect of ISWs loads on Floating Production Storage and Offloading(FPSO) is studied in this paper. The application conditions of KdV, eKdV and MCC ISWs theories are used in the numerical method. The depthaverage...Scale effect of ISWs loads on Floating Production Storage and Offloading(FPSO) is studied in this paper. The application conditions of KdV, eKdV and MCC ISWs theories are used in the numerical method. The depthaveraged velocities induced by ISWs are used for the velocity-inlet boundary. Three scale ratio numerical models λ=1, 20 and 300 were selected, which the scale ratio is the size ratio of numerical models to the experimental model.The comparisons between the numerical and former experimental results are performed to verify the feasibility of numerical method. The comparisons between the numerical and simplified theoretical results are performed to discuss the applicability of the simplified theoretical model summarized from the load experiments. Firstly, the numerical results of λ=1 numerical model showed a good agreement with former experimental and simplified theoretical results. It is feasible to simulate the ISWs loads on FPSO by the numerical method. Secondly, the comparisons between the results of three scale ratio numerical models and experimental results indicated that the scale ratios have more significant influence on the experimental horizontal forces than the vertical forces. The scale effect of horizontal forces mainly results from the different viscosity effects associated with the model’s dimension.Finally, through the comparisons between the numerical and simplified theoretical results for three scale ratio models, the simplified theoretical model of the pressure difference and friction forces exerted by ISWs on FPSO is applied for large-scale or full-scale FPSO.展开更多
Numerical simulations based on a high-resolution three-dimensional MIT general circulation model(MITgcm)using realistic topography and tidal forcing are conducted to investigate the generation and propagation of the s...Numerical simulations based on a high-resolution three-dimensional MIT general circulation model(MITgcm)using realistic topography and tidal forcing are conducted to investigate the generation and propagation of the so-called type-a waves(large-amplitude rank-ordered wave packets)and type-b waves(isolated wave packets)in the northern South China Sea.At first,we summarized and analyzed the generation and propagation characteristics of these waves.Then,energy budget at the Luzon Strait is calculated.Energy generation has three local maxima every day,of which the largest one corresponds to the emergence of the type-a wave.Energy flux at the west boundary of the Luzon Strait shows two local maxima each day.The larger one is consistent with the generation of the type-a wave and the smaller one is in correspondence with the generation of the type-b wave.Sensitivity experiments are designed to explore the role of the east and west ridge of the Luzon Strait on the generation and propagation of the type-a and type-b waves.It is found that the east ridge is indispensable on the generation of the type-a wave while the west ridge has little contribution.The west ridge diminishes the type-a waves'amplitude but hardly changes their propagation speed.The type-b waves also come from perturbation signals which originate from the east ridge and are enhanced in amplitude and reduced in propagation speed by the west ridge.展开更多
Internal solitary waves(ISWs)are ubiquitous in the Andaman Sea,as revealed by synthetic aperture radar images;however,their generation mechanisms and corresponding influencing factors remain unknown.Based on a nonhydr...Internal solitary waves(ISWs)are ubiquitous in the Andaman Sea,as revealed by synthetic aperture radar images;however,their generation mechanisms and corresponding influencing factors remain unknown.Based on a nonhydrostatic two-dimensional model,the generation of ISW packets along the transect of a channel lying between Batti Malv Island and Car Nicobar Island is investigated.Moreover,the influences of topographic characteristics,seasonal stratifications,and tidal forcings are analyzed through a series of sensitivity runs.The simulation results indicate that bidirectional rank-ordered ISW packets are generated by the nonlinear steepening of internal tides.An east-west ISW asymmetry is observed,which is attributed to distinct topographic characteristics.The surrounding sills can also generate internal wave beams,which modulate the intensity of ISWs.However,the topographic structure of the west flank of the ridge mainly contributes to the suppression of westward ISWs,which decreases the modulating effect of internal wave beams.During the spring tide,the generation of ISWs is enhanced.During the neap tide,ISWs are weak,and the east-west ISW asymmetry is less obvious.Moreover,seasonal stratification only has a minor effect on the generation and evolution of ISWs.展开更多
Based on field wave data, an empirical formula of wave envelope spectrum is given in this paper. Then the methods of both numerical and physical simulation of sea wave groups with the given spectrum and groupiness par...Based on field wave data, an empirical formula of wave envelope spectrum is given in this paper. Then the methods of both numerical and physical simulation of sea wave groups with the given spectrum and groupiness parameters are suggested.展开更多
This paper is concerned with particle trajectories beneath solitary waves when a linear shear current exists.The fluid is assumed to be incompressible and inviscid,lying on a flat bed.Classical asymptotic expansion is...This paper is concerned with particle trajectories beneath solitary waves when a linear shear current exists.The fluid is assumed to be incompressible and inviscid,lying on a flat bed.Classical asymptotic expansion is used to obtain a Korteweg-de Vries(Kd V)equation,then a forth-order Runge-Kutta method is applied to get the approximate particle trajectories.On the other hand,our particular attention is paid to the direct numerical simulation(DNS)to the original Euler equations.A conformal map is used to solve the nonlinear boundary value problem.Highaccuracy numerical solutions are then obtained through the fast Fourier transform(FFT)and compared with the asymptotic solutions,which shows a good agreement when wave amplitude is small.Further,it also yields that there are different types of particle trajectories.Most surprisingly,periodic motion of particles could exist under solitary waves,which is due to the wave-current interaction.展开更多
A three dimensional(3D)numerical wave flume is used to investigate carefully the ISWs(Internal solitary wave)forces acting on cylinders interacting with a stratified shear environment.Using the Large-Eddy Simulation(L...A three dimensional(3D)numerical wave flume is used to investigate carefully the ISWs(Internal solitary wave)forces acting on cylinders interacting with a stratified shear environment.Using the Large-Eddy Simulation(LES)approach and analyzing the distribution of shear stress and pressure along the surface of the cylinder,the differential pressure resistance and the viscous force are obtained.The method of multiple linear regression analysis is adopted and a comprehensive influence coefficient is determined accordingly to account for the dimensionless forces acting on the cylinder.Results show that the differential pressure resistance on a square cylinder is 1.5 times higher than that on a circular cylinder in the upper layer,while the differential pressure resistance on a square cylinder is 3.5 times larger than that on a circular cylinder in the lower layer.The viscous force is 1–2 orders of magnitude smaller than the differential pressure resistance,which means that the viscous force could be ignored.The comprehensive influence coefficient shows positive correlation with the relative wave height and negative correlation with upper and lower water depth ratio.展开更多
Numerous internal solitary waves(ISWs)have been observed in the southern Andaman Sea.In this study,the twodimensional Massachusetts Institute of Technology general circulation model is applied to investigate the dynam...Numerous internal solitary waves(ISWs)have been observed in the southern Andaman Sea.In this study,the twodimensional Massachusetts Institute of Technology general circulation model is applied to investigate the dynamics of ISWs and explore the effects of the bottom topography and tidal forcing on the generation and propagation of ISWs in the southern Andaman Sea.The results show that the large-amplitude depression ISWs are mainly generated via the oscillating tidal flow over the sill of the Great Channel,and the generation of ISWs is subject to the lee wave regime.The Dreadnought Bank cannot generate ISWs itself;however,it can enhance the amplitudes of eastward-propagating ISWs generated from sill A,owing to constructive interference of internal tide generation between the sill of the Great Channel and the Dreadnought Bank.The eastward-propagating ISWs generated by the eastern shallow sill near the continental shelf can propagate to the shelf,where they evolve into elevation waves because of the shallow water.Sensitivity runs show that both the semidiurnal and diurnal tides over the sill of the Great Channel can generate ISWs in this area.However,the ISWs generated by diurnal tides are much weaker than those generated by semidiurnal tides.Mixed tidal forcing has no significant effect on the generation of ISWs.展开更多
基金Project supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA01020304)the National Natural Science Foundation of China(Grant Nos.91026005,11547304,11275156,11047010,and 61162017)
文摘A nonlinear Schrodinger equation in one-dimensional bead chain is first obtained and an envelope solitary wave of the system is verified numerically in this system. The reflection and the transmission of an incident envelope solitary wave due to impurities has also been investigated. It is found that the magnitudes of both the reflection and the transmission not only depend on the characters of impurity materials, the wave number, the incident wave amplitude, but also on the impurity number. This can be used to detect the character and the number of the impurity materials in the bead chain by measuring the reflection and the transmission of an incident pulse.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11275156,11547304 and 11505261
文摘Reflections of a Korteweg-de Vries (KdV) solitary wave and an envelope solitary wave are studied by using the particle-in-cell simulation method. Defining the phase shift of the reflected solitary wave, we notice that there is a phase shift of the reflected KdV solitary wave, while there is no phase shift for an envelope solitary wave. It is also noted that the reflection of a KdV solitary wave at a solid boundary is equivalent to the head-on collision between two identical amplitude solitary waves.
基金financially supported by the National Key R&D Program of China(Grant No.2017YFC1404202)the National Natural Science Foundation of China(Grant No.11572332)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant Nos.XDB22040203 and XDA22000000)。
文摘Wave forces acting on a vertical cylinder at different locations on a slope beach in the near-shore region are investigated considering solitary waves as incoming waves.Based on the Reynolds-averaged Navier-Stokes equations and the k-ε turbulence model,wave forces due to the interaction between the solitary wave and cylinder are simulated and analyzed with different incident wave heights and cylinder locations.The numerical results are first compared with previous theoretical and experimental results to validate the model accuracy.Then,the wave forces and characteristics around the cylinder are studied,including the velocity field,wave surface elevation and pressure.The effects of relative wave height,Keulegan-Carpenter(KC)number and cylinder locations on the wave forces are also discussed.The results show that the wave forces exerted on a cylinder exponentially increase with the increasing incident wave height and KC number.Before the wave force peaks,the growth rate of the wave force shows an increasing trend as the cylinder moves onshore.The cylinder location has a notable effect on the wave force on the cylinder in the near-shore region.As the cylinder moves onshore,the wave force on the cylinder initially increases and then decreases.For the cases considered here,the maximum wave force appears when the cylinder is located one cylinder diameter below the still-water shoreline.Furthermore,the fluid velocity peaks when the maximum wave force appears at the same location.
基金financially supported by the National Natural Science Foundation of China(Grant No.11372184)the National Basic Research Program of China(973 Program,Grant Nos.2015CB251203-3 and 2013CB036103)
文摘Scale effect of ISWs loads on Floating Production Storage and Offloading(FPSO) is studied in this paper. The application conditions of KdV, eKdV and MCC ISWs theories are used in the numerical method. The depthaveraged velocities induced by ISWs are used for the velocity-inlet boundary. Three scale ratio numerical models λ=1, 20 and 300 were selected, which the scale ratio is the size ratio of numerical models to the experimental model.The comparisons between the numerical and former experimental results are performed to verify the feasibility of numerical method. The comparisons between the numerical and simplified theoretical results are performed to discuss the applicability of the simplified theoretical model summarized from the load experiments. Firstly, the numerical results of λ=1 numerical model showed a good agreement with former experimental and simplified theoretical results. It is feasible to simulate the ISWs loads on FPSO by the numerical method. Secondly, the comparisons between the results of three scale ratio numerical models and experimental results indicated that the scale ratios have more significant influence on the experimental horizontal forces than the vertical forces. The scale effect of horizontal forces mainly results from the different viscosity effects associated with the model’s dimension.Finally, through the comparisons between the numerical and simplified theoretical results for three scale ratio models, the simplified theoretical model of the pressure difference and friction forces exerted by ISWs on FPSO is applied for large-scale or full-scale FPSO.
基金The National Key Research and Development Plan of China under contract No.2016YFC1401300the National Natural Science Foundation of China under contract No.41276008the Taishan Scholars Program
文摘Numerical simulations based on a high-resolution three-dimensional MIT general circulation model(MITgcm)using realistic topography and tidal forcing are conducted to investigate the generation and propagation of the so-called type-a waves(large-amplitude rank-ordered wave packets)and type-b waves(isolated wave packets)in the northern South China Sea.At first,we summarized and analyzed the generation and propagation characteristics of these waves.Then,energy budget at the Luzon Strait is calculated.Energy generation has three local maxima every day,of which the largest one corresponds to the emergence of the type-a wave.Energy flux at the west boundary of the Luzon Strait shows two local maxima each day.The larger one is consistent with the generation of the type-a wave and the smaller one is in correspondence with the generation of the type-b wave.Sensitivity experiments are designed to explore the role of the east and west ridge of the Luzon Strait on the generation and propagation of the type-a and type-b waves.It is found that the east ridge is indispensable on the generation of the type-a wave while the west ridge has little contribution.The west ridge diminishes the type-a waves'amplitude but hardly changes their propagation speed.The type-b waves also come from perturbation signals which originate from the east ridge and are enhanced in amplitude and reduced in propagation speed by the west ridge.
基金This work was supported by the National Natural Science Foundation of China(No.41876012)the National Basic Research Program of China(973 Program)(No.2017YFC1405605)the Fundamental Research Funds for the Central Universities(No.202061001).
文摘Internal solitary waves(ISWs)are ubiquitous in the Andaman Sea,as revealed by synthetic aperture radar images;however,their generation mechanisms and corresponding influencing factors remain unknown.Based on a nonhydrostatic two-dimensional model,the generation of ISW packets along the transect of a channel lying between Batti Malv Island and Car Nicobar Island is investigated.Moreover,the influences of topographic characteristics,seasonal stratifications,and tidal forcings are analyzed through a series of sensitivity runs.The simulation results indicate that bidirectional rank-ordered ISW packets are generated by the nonlinear steepening of internal tides.An east-west ISW asymmetry is observed,which is attributed to distinct topographic characteristics.The surrounding sills can also generate internal wave beams,which modulate the intensity of ISWs.However,the topographic structure of the west flank of the ridge mainly contributes to the suppression of westward ISWs,which decreases the modulating effect of internal wave beams.During the spring tide,the generation of ISWs is enhanced.During the neap tide,ISWs are weak,and the east-west ISW asymmetry is less obvious.Moreover,seasonal stratification only has a minor effect on the generation and evolution of ISWs.
文摘Based on field wave data, an empirical formula of wave envelope spectrum is given in this paper. Then the methods of both numerical and physical simulation of sea wave groups with the given spectrum and groupiness parameters are suggested.
基金supported by the Key Research Program of Frontier Sciences,Chinese Academy of Sciences(No.QYZDBSSWSYS015)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB22040203)the support from Chinese Academy of Sciences Center for Excellence in Complex System Mechanics。
文摘This paper is concerned with particle trajectories beneath solitary waves when a linear shear current exists.The fluid is assumed to be incompressible and inviscid,lying on a flat bed.Classical asymptotic expansion is used to obtain a Korteweg-de Vries(Kd V)equation,then a forth-order Runge-Kutta method is applied to get the approximate particle trajectories.On the other hand,our particular attention is paid to the direct numerical simulation(DNS)to the original Euler equations.A conformal map is used to solve the nonlinear boundary value problem.Highaccuracy numerical solutions are then obtained through the fast Fourier transform(FFT)and compared with the asymptotic solutions,which shows a good agreement when wave amplitude is small.Further,it also yields that there are different types of particle trajectories.Most surprisingly,periodic motion of particles could exist under solitary waves,which is due to the wave-current interaction.
基金the Jiangxi Natural Science Foundation of China[Grant No.20202BABL214050]the Sci-tech Program by Jiangxi Provincial Education Department of China[Grant No.GJJ190942].
文摘A three dimensional(3D)numerical wave flume is used to investigate carefully the ISWs(Internal solitary wave)forces acting on cylinders interacting with a stratified shear environment.Using the Large-Eddy Simulation(LES)approach and analyzing the distribution of shear stress and pressure along the surface of the cylinder,the differential pressure resistance and the viscous force are obtained.The method of multiple linear regression analysis is adopted and a comprehensive influence coefficient is determined accordingly to account for the dimensionless forces acting on the cylinder.Results show that the differential pressure resistance on a square cylinder is 1.5 times higher than that on a circular cylinder in the upper layer,while the differential pressure resistance on a square cylinder is 3.5 times larger than that on a circular cylinder in the lower layer.The viscous force is 1–2 orders of magnitude smaller than the differential pressure resistance,which means that the viscous force could be ignored.The comprehensive influence coefficient shows positive correlation with the relative wave height and negative correlation with upper and lower water depth ratio.
基金supported by the Key Research Program of Frontier Sciences,Chinese Academy of Sciences(Grant No.QYZDJ-SSW-DQC034)the Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(Grant No.GML2019ZD0304)+8 种基金the National Natural Science Foundation of China(Nos.41521005,41776007 and 41776008)the Chinese Academy of Sciences(Grant No.ISEE2021-PY01)the Guangzhou Science and Technology Program(Grant No.201804010373)the Guangdong Natural Science Foundation(Grant No.2020A1514010495)the Youth Science and Technology Innovation Talent of Guangdong TeZhi Plan(Grant No.2019TQ05H519)the Pearl River S&T Nova Program of Guangzhou(Grant No.201806010091)the Youth Innovation Promotion Association of CAS(Grant No.2018378)the LTO Independent Research Program(Grant No.LTOZZ2001)the Rising Star Foundation of SCSIO(Grant No.NHXX2019WL0201).
文摘Numerous internal solitary waves(ISWs)have been observed in the southern Andaman Sea.In this study,the twodimensional Massachusetts Institute of Technology general circulation model is applied to investigate the dynamics of ISWs and explore the effects of the bottom topography and tidal forcing on the generation and propagation of ISWs in the southern Andaman Sea.The results show that the large-amplitude depression ISWs are mainly generated via the oscillating tidal flow over the sill of the Great Channel,and the generation of ISWs is subject to the lee wave regime.The Dreadnought Bank cannot generate ISWs itself;however,it can enhance the amplitudes of eastward-propagating ISWs generated from sill A,owing to constructive interference of internal tide generation between the sill of the Great Channel and the Dreadnought Bank.The eastward-propagating ISWs generated by the eastern shallow sill near the continental shelf can propagate to the shelf,where they evolve into elevation waves because of the shallow water.Sensitivity runs show that both the semidiurnal and diurnal tides over the sill of the Great Channel can generate ISWs in this area.However,the ISWs generated by diurnal tides are much weaker than those generated by semidiurnal tides.Mixed tidal forcing has no significant effect on the generation of ISWs.