The interaction between waves and currents in the ocean often complicates the flow field around structures.In this study,a three-dimensional integrated numerical model was established to investigate the seabed respons...The interaction between waves and currents in the ocean often complicates the flow field around structures.In this study,a three-dimensional integrated numerical model was established to investigate the seabed response and liquefaction around a mono-pile under different wave-current interaction angles.In the present model,the Reynolds-averaged Navier-Stokes equations were used to simulate the flow field,and the Biot's poro-elastic theory was adopted to calculate the seabed response caused by crossing wave-current loading.Unlike previous studies,the load on the mono-pile was considered,and the wave-current interaction angle was extended to 180°,which was more in line with practical engineering problems.The numerical results were in a good agreement with the experimental measurements.The results indicated that waves interacted with currents in a large angle could result in a large momentary liquefaction depth of the seabed.The parametric studies proved that the position of the front and two sides of the pile was relatively safer compared with that of the leeside of the pile,and the surface of the seabed downstream of the pile was liable to liquefy.展开更多
The vortex-induced nonlinear vibration of casing pipes in the deep water was studied considering the loads of current and combined wave-current. The vortex-induced vibration equation of a casing pipe was set up consid...The vortex-induced nonlinear vibration of casing pipes in the deep water was studied considering the loads of current and combined wave-current. The vortex-induced vibration equation of a casing pipe was set up considering the beam mode and Morison’s nonlinear fluid loads as well as the vortex-excited loads. The approach of calculating vortex-excited nonlinear vibration by Galerkin’s method was proposed. The natural vibration frequencies and modes were obtained, and the response including primary resonance induced by current and the composite resonance under combined wave-current for the 170 m long casing pipe in the 160m depth of water were investigated. The results show that the dynamics response of casing pipe obviously increases, and the complicated response behaviors of casing pipe are described under combined wave-current.展开更多
-A composite pipeline is defined as a pipeline system composed of one big pipe and one or several small pipes. Based on the theory of wave- current interaction and physical model test, the hydrodynamic characteristics...-A composite pipeline is defined as a pipeline system composed of one big pipe and one or several small pipes. Based on the theory of wave- current interaction and physical model test, the hydrodynamic characteristics of the submarine composite pipeline in wave-current coexisting field (both regular and irregular waves) are investigated. The so-called "modified diameter method" is used for analyzing the in-fine hydrodynamic coefficients of the composite pipeline, which are well related to KC number. The comparison of test data for regular and irregular waves shows that in the region of 90 】 KC】 20, the results in these two cases can be unified. The effect of water depth is analyzed in details. The relationships between CD, CM and KC , which are based on the results of present research, may be used as a reference in engineering design.展开更多
-Based on the extended Morison Equation and model tests, the in-line forces on small square cylinders caused by waves (regular and irregular) and currents are analyzed in detail in this paper. The hydrodynamic coeffic...-Based on the extended Morison Equation and model tests, the in-line forces on small square cylinders caused by waves (regular and irregular) and currents are analyzed in detail in this paper. The hydrodynamic coefficient CD and Cu related to KC number and the effect of direction of wave incidence are also given, which can be used in engineering practice.展开更多
Wave-current interaction and its effects on the hydrodynamic environment in the Beibu Gulf(BG) have been investigated via employing the Coupled Ocean–Atmosphere–Wave–Sediment Transport(COAWST) modeling system. The ...Wave-current interaction and its effects on the hydrodynamic environment in the Beibu Gulf(BG) have been investigated via employing the Coupled Ocean–Atmosphere–Wave–Sediment Transport(COAWST) modeling system. The model could simulate reasonable hydrodynamics in the BG when validated by various observations.Vigorous tidal currents refract the waves efficiently and make the seas off the west coast of Hainan Island be the hot spot where currents modulate the significant wave height dramatically. During summer, wave-enhanced bottom stress could weaken the near-shore component of the gulf-scale cyclonic-circulation in the BG remarkably, inducing two major corresponding adjustments: Model results reveal that the deep-layer cold water from the southern BG makes critical contribution to maintaining the cold-water mass in the northern BG Basin.However, the weakened background circulation leads to less cold water transported from the southern gulf to the northern gulf, which finally triggers a 0.2℃ warming in the cold-water mass area;In the top areas of the BG, the suppressed background circulation reduces the transport of the diluted water to the central gulf. Therefore, more freshwater could be trapped locally, which then triggers lower sea surface salinity(SSS) in the near-field and higher SSS in the far-field.展开更多
—In this paper the parabolic approximation model based on mild-slope equation is used tostudy wave propagation over a slowly varying and frictional topography under wave-current interaction.A governing equation consi...—In this paper the parabolic approximation model based on mild-slope equation is used tostudy wave propagation over a slowly varying and frictional topography under wave-current interaction.A governing equation considering the friction effects is derived by the authors for the first time.A simpli-fied form for the rate of wave energy dissipation is presented on the basis of the wave-current action conser-vation equation and the bottom friction model given by Yoo and O'connor(1987).Examples reveal thatthe present computational method can be used for the calculation of wave elements for actual engineeringprojects with large water areas.展开更多
We examined the influences of the wind fi eld and wave-current interaction(WCI)on the numerical simulation results of typhoon-induced wind waves in the northern East China Sea(NECS)using the coupled Simulating Waves N...We examined the influences of the wind fi eld and wave-current interaction(WCI)on the numerical simulation results of typhoon-induced wind waves in the northern East China Sea(NECS)using the coupled Simulating Waves Nearshore+Advanced Circulation(SWAN+ADCIRC)model.The simulations were performed during two typhoon events(Lekima and Muifa),and two widely used reanalysis wind fields,the Climate Forecast System Version 2(CFSv2)from the National Centers for Environmental Prediction(NCEP)and the fifth-generation European Centre for Medium-Range Weather Forecasts(ECMWF)Reanalysis(ERA5),were compared.The results indicate that the ERA5 and CFSv2 wind fields both reliably reproduced the wind variations measured by in-situ buoys,and the accuracy of the winds from ERA5 were generally better than those from CFSv2 because CFSv2 tended to overestimate the wind speed and the simulated significant wave height(SWH),particularly the peak SWH.The WCI effects between the two wind field simulations were similar;these effects enhanced the SWH throughout the nearshore NECS during both typhoons but suppressed the SWH on the right side of the Typhoon Muifa track in the deep and off shore sea areas.In summary,variations in the water depth and current propagation direction dominate the modulation of wave height.展开更多
Coastal wave energy resources have enormous exploitation potential due to shorter weather window,closer installation distance and lower maintenance cost.However,impact loads generated by depth variation from offshore ...Coastal wave energy resources have enormous exploitation potential due to shorter weather window,closer installation distance and lower maintenance cost.However,impact loads generated by depth variation from offshore to nearshore and wave-current interaction,may lead to a catastrophic damage or complete destruction to wave energy converters(WECs).This objective of this paper is to investigate slamming response of a coastal oscillating wave surge converter(OWSC)entering or leaving water freely.Based on fully nonlinear potential flow theory,a time-domain wave-current-structure interaction model combined with higher-order boundary element method(HOBEM),is developed to analyze the coupled hydrodynamic problem.The variable-depth seabed is considered in the model to illustrate the shallow water effect on impact loads and free surface profiles in coastal zone.A domain decomposition approach is utilized to simulate the overlapping phenomenon generated by a jet falling into water under gravity effect.Through a series of Lagrangian interpolation methods,the meshes on boundaries are rearranged to avoid the mismatch between element size on free surface and body surface.The present model is validated against the existing experimental and numerical results.Simulations are also provided for the effects of wave-current interaction and uneven local seabed on the slamming responses.It is found that the length of the splash jet increases for a following current and decreases for an opposing current,and that the slamming response of the OWSC device is sensitive to the geometric features of the uneven seabed.展开更多
- The wave-current forces on vertical piles in side-by-side arrangement induced by irregular waves with opposing current are investigated experimentally in this paper. The characteristics in both time and frequency do...- The wave-current forces on vertical piles in side-by-side arrangement induced by irregular waves with opposing current are investigated experimentally in this paper. The characteristics in both time and frequency domain of in-line, lift and resultant forces are analyzed. The grouping effect coefficients of inline, lift and resultant forces on piles related to KC number and relative spacing parameters are given. These results are compared with those in the case of irregular waves combined with following currents. It is found that the results in these two cases are quite different. The range of KC number tested is 10- 60, the range of Reynolds number is (0.55-3.43) ×104.展开更多
- A composite pipeline is defined as a main big pipe composed of one or several small pipes. The flow behaviour around a submarine composite pipeline is more complicated than that around a single submarine pipeline. A...- A composite pipeline is defined as a main big pipe composed of one or several small pipes. The flow behaviour around a submarine composite pipeline is more complicated than that around a single submarine pipeline. A series model test of composite pipelines in a wave-current coexisting field was conducted by the authors. Both in-line and lift forces were measured, and the resultant forces were also analyzed. The results of lift forces and resultant forces are reported in this paper. It is found that the lift force coefficients for composite pipelines are well related to the KC number. The lift force coefficients for an irregular wave-current coexisting field are smaller than those for a regular wave-current coexisting field. The frequency of lift force is usually twice the wave frequency or higher. The authors test indicates that the resultant forces are about 10 to 20 percent larger than in-line forces (horizontal forces). The effect of water depth is analyzed. Finally, the relationship between lift展开更多
Pile foundations have been widely used in offshore engineering.In this study,a three-dimensional numerical model was used to investigate the seabed response around a mono-pile under wave-current loading.Reynolds-avera...Pile foundations have been widely used in offshore engineering.In this study,a three-dimensional numerical model was used to investigate the seabed response around a mono-pile under wave-current loading.Reynolds-averaged Navier-Stokes equations were used to simulate the flow field,and Biot's consolidation equations were used for simulating the response of a porous seabed.The pore water pressure within soil and the effective stress along the depth of the seabed were simulated for various current velocities,with currents traveling either along or against the wave.Results indicate that the current has a significant effect on the effective stress and the pore water pressure distributions,which increases with the current velocity,and that the current traveling against the wave increases the liquefaction depth of the porous seabed.展开更多
The nonlinear dynamic response induced by the wave-current interaction on a deepwater steep wave riser(SWR)is numerically investigated based on a three-dimensional(3 D)time-domain finite element method(FEM).The govern...The nonlinear dynamic response induced by the wave-current interaction on a deepwater steep wave riser(SWR)is numerically investigated based on a three-dimensional(3 D)time-domain finite element method(FEM).The governing equation considering internal flow is established in the global coordinate system.The whole SWR consists of three segments:the decline segment,buoyancy segment and hang-off segment,in which the buoyancy segment is wrapped by several buoyancy modules in the middle section,leading to the arch bend and sag bend.A Newmark-β iterative scheme is adopted for the accurate analysis to solve the governing equation and update the dynamic response at each time step.The proposed method is verified through the published results for the dynamic response of steel catenary riser(SCR)and static configuration of steel lazy wave riser(SLWR).Simulations are executed to study the influence of wave height,current velocity/direction,internal flow density/velocity and top-end pressure on the tension,configuration and bending moment of the SWR.The results indicate that the influence of the current on the configuration and mechanical behavior of the SWR is greater than that of the wave,especially in the middle section.With increasing current velocity,the suspending height of the middle section drops,meanwhile,its bending moment decreases accordingly,but the tension increases significantly.For a fixed external load,the increasing internal flow density induces the amplification of the tension at the hang-off segment and the mitigation at the decline segment,while the opposite trend occurs at the bending moment.展开更多
On the basis of the measurement data pertaining to waves, current, and sediment in February 2012 in the mouth bar of the Modaomen Estuary, the Soulsby formulae with an iterative method are applied to calculating botto...On the basis of the measurement data pertaining to waves, current, and sediment in February 2012 in the mouth bar of the Modaomen Estuary, the Soulsby formulae with an iterative method are applied to calculating bottom shear stresses(BSS) and their effect on a sediment re-suspension. Swell- induced BSS have been found to be the most important part of the BSS. In this study, the correlation coefficient between a wavecurrent shear stress and SSC is 0.86, and that between current shear stresses and SSC is only 0.40. The peaks of the SSC are consistent with the height and the BSS of the swell. The swell is the main mechanism for the sediment re-suspension, and the tidal current effect on sediment re-suspension is small. The peaks of the SSC are centered on the high tidal level, and the flood tide enhances the wave shear stresses and the SSC near the bottom. The critical shear stress for sediment re-suspension at the observation station is between 0.20 and 0.30 N/m2. Tidal currents are too weak to stir up the bottom sediment into the flow, but a WCI(wave-current interaction) is strong enough to re-suspend the coarse sediment.展开更多
A higher order boundary element method (HOBEM) is implemented for wave-current action on structures. The free-term coefficient and Cauchy principal value (CPV) integrals are computed by direct methods. Numerical exper...A higher order boundary element method (HOBEM) is implemented for wave-current action on structures. The free-term coefficient and Cauchy principal value (CPV) integrals are computed by direct methods. Numerical experiments are carried out to validate the computation of free-term coefficient and CPV integrals. The results show that the computation precision of free-term coefficient is very high for various bodies, even with edges and corners, and the convergence speed is fast for CPV integrals for different meshes. The comparison of the second order mean drift force due to wave-current action on a uniform cylinder is made with an analytic solution. It is found that good agreement exists between the present calculation and the analytic solutions. Finally, the numerical code is applied for computing wave-current action on Snorre TLP.展开更多
The movement of sediment in estuary and on coast is directly restricted by the bed shear stress. Therefore, the research on the basic problem of sediment movement by the bed shear stress is an important way to researc...The movement of sediment in estuary and on coast is directly restricted by the bed shear stress. Therefore, the research on the basic problem of sediment movement by the bed shear stress is an important way to research the theory of sediment movement. However, there is not a measuring and computing method to measure the bed shear stress under a complicated dynamic effect like wave and current. This paper describes the measurement and test research on the bed shear stress in a long launder of direct current by the new instrument named thermal shearometer based on micro-nanotechnology. As shown by the research results, the thermal shearometer has a high response frequency and strong stability. The measured results can reflect the basic change of the bed shear stress under wave and wave?current effect, and confirm that the method of measuring bed shear stress under wave?current effect with thermal shearometer is feasible. Meanwhile, a preliminary method to compute the shear stress compounded by wave?current is put forward according to the tested and measured results, and then a reference for further study on the basic theory of sediment movement under a complicated dynamic effect is provided.展开更多
We investigated the Stokes drift-driven ocean currents and Stokes drift-induced wind energy input into the upper ocean using a two-way coupled wave-current modeling system that consists of the Princeton Ocean Model ge...We investigated the Stokes drift-driven ocean currents and Stokes drift-induced wind energy input into the upper ocean using a two-way coupled wave-current modeling system that consists of the Princeton Ocean Model generalized coordinate system (POMgcs), Simulating WAves Nearshore (SWAN) wave model, and the Model Coupling Toolkit (MCT). The Coriolis-Stokes forcing (CSF) computed using the wave parameters from SWAN was incorporated with the momentum equation of POMgcs as the core coupling process. Experimental results in an idealized setting show that under the steady state, the scale of the speed of CSF-driven current was 0.001 m/s and the maximum reached 0.02 m/s. The Stokes drift-induced energy rate input into the model ocean was estimated to be 28.5 GW, taking 14% of the direct wind energy rate input. Considering the Stokes drift effects, the total mechanical energy rate input was increased by approximately 14%, which highlights the importance of CSF in modulating the upper ocean circulation. The actual run conducted in Taiwan Adjacent Sea (TAS) shows that: 1) CSF-based wave-current coupling has an impact on ocean surface currents, which is related to the activities of monsoon winds; 2) wave-current coupling plays a significant role in a place where strong eddies present and tends to intensify the eddy's vorticity; 3) wave-current coupling affects the volume transport of the Taiwan Strait (TS) throughflow in a nontrivial degree, 3.75% on average.展开更多
Large eddy simulation is performed to study three-dimensional wave-current interaction with a square cylinder at different Reynolds numbers, ranging from 1,000 to 600,000. The Keulegan-Carpenter number is relevantly a...Large eddy simulation is performed to study three-dimensional wave-current interaction with a square cylinder at different Reynolds numbers, ranging from 1,000 to 600,000. The Keulegan-Carpenter number is relevantly a constant of 0.6 for all cases. The Strouhal number, the mean and the RMS values of the effective drag coefficient in the streamwise and transverse directions are computed for various Reynolds numbers, and the velocity of a representative point in the turbulent zone is simulated to find the turbulent feature. It is found that the wave-current interaction should be considered as three-dimensional flow when the Reynolds number is high; under wave-current effect, there exists a critical Reynolds number, and when the Reynolds number is smaller than the critical one, current effect on wave can be nearly neglected; conversely, with the Reynolds number increasing, wave-current- structure interaction is sensitive to the Reynolds number.展开更多
In order to study the mechanism of flow-sediment movement, it is essential to obtain measured data of water hydrodynamic and sediment concentration process with high spatial and temporal resolution in the bottom bound...In order to study the mechanism of flow-sediment movement, it is essential to obtain measured data of water hydrodynamic and sediment concentration process with high spatial and temporal resolution in the bottom boundary layer(BBL). Field observations were carried out in the northwest Caofeidian sea area in the Bohai Bay. Near 2 m isobath(under the lowest tidal level), a tripod system was installed with AWAC(Acoustic Wave And Current), ADCP(Acoustic Doppler Current Profilers), OBS-3A(Optical Backscatter Point Sensor), ADV(Acoustic Doppler Velocimeters), etc. The accurate measurement of the bottom boundary layer during a single tidal period was carried out, together with a long-term sediment concentration measurement under different hydrological conditions. All the measured data were used to analyze the characteristics of wave-current-sediment movement and the BBL. Analysis was performed on flow structure, shear stress, roughness, eddy viscosity and other parameters of the BBL. Two major findings were made. Firstly, from the measured data, the three-layer distribution model of the velocity profiles and eddy viscosities in the wave-current BBL are proposed in the observed sea area; secondly, the sediment movement is related closely to wind-waves in the muddy coast area where sediment is clayey silt: 1) The observed suspended sediment concentration under light wind conditions is very low, with the peak value generally smaller than 0.1 kg/m3 and the average value being 0.03 kg/m3; 2) The sediment concentration increases continuously under the gales over 6-7 in Beaufort scale, under a sustained wind action. The measured peak sediment concentration at 0.4 m above the seabed is 0.15-0.32 kg/m3, and the average sediment concentration during wind-wave action is 0.08-0.18 kg/m3, which is about 3-6 times the value under light wind conditions. The critical wave height signaling remarkable changes of sediment concentration is 0.5 m. The results show that the suspended load sediment concentration is mainly influenced by wave-induced sediment suspension.展开更多
The northern South China Sea(SCS) is frequently affected by typhoons. During severe storm events, wave-current interactions produce storm surges causing enormous damage in the path of the typhoon. To evaluate the infl...The northern South China Sea(SCS) is frequently affected by typhoons. During severe storm events, wave-current interactions produce storm surges causing enormous damage in the path of the typhoon. To evaluate the influence of wave-current interactions on storm surge, we used a coupled ocean-atmospherewave-sediment transport(COAWST) modeling system with radiation-stress and vortex-force formulations to simulate two typically intense tropical storms that invaded the SCS, namely Typhoons Nuri(2008) and Hagupit(2008), and compared results with observations from the Hong Kong Observatory. Both radiationstress and vortex-force formulations significantly improved the accuracy of the simulation. Depending on which typhoon and the topography encountered, the influence of surface waves on the oceanic circulation showed different characteristics, including the differences of range and intensity of storm surge between vortex-force and radiation-stress experiments. During typhoon landing, strong sea-surface elevation in concert with wave set-up/set-down caused the adjustment of the momentum balance. In the direction perpendicular to the current, but especially in the cross-shore direction, the pressure gradient and wave effects on the current dominated the momentum balance.展开更多
This letter presents a new analytical approximation for wave (current)-induced dynamic soil response in marine sediments. In the model, the third-order approximation for wave-current interactions is employed for the f...This letter presents a new analytical approximation for wave (current)-induced dynamic soil response in marine sediments. In the model, the third-order approximation for wave-current interactions is employed for the flow model, while Biot's dynamic poro-elastic model is used to simulate the porous flow in a seabed. The newly analytical solution is validated with the field observations. Based on the solution, effects of currents and wave-nonlinearity on soil response are examined and a parametric study will be carried out to examine the influence of currents onthe liquefaction potential.展开更多
基金supported by the Key Project of NSFC-Shangdong Joint Research Funding POW3C(Grant No.U1906230).
文摘The interaction between waves and currents in the ocean often complicates the flow field around structures.In this study,a three-dimensional integrated numerical model was established to investigate the seabed response and liquefaction around a mono-pile under different wave-current interaction angles.In the present model,the Reynolds-averaged Navier-Stokes equations were used to simulate the flow field,and the Biot's poro-elastic theory was adopted to calculate the seabed response caused by crossing wave-current loading.Unlike previous studies,the load on the mono-pile was considered,and the wave-current interaction angle was extended to 180°,which was more in line with practical engineering problems.The numerical results were in a good agreement with the experimental measurements.The results indicated that waves interacted with currents in a large angle could result in a large momentary liquefaction depth of the seabed.The parametric studies proved that the position of the front and two sides of the pile was relatively safer compared with that of the leeside of the pile,and the surface of the seabed downstream of the pile was liable to liquefy.
基金Project supported by the National Natural Science Foundation of China (No.50279026) andthe National985Engineering Project in China
文摘The vortex-induced nonlinear vibration of casing pipes in the deep water was studied considering the loads of current and combined wave-current. The vortex-induced vibration equation of a casing pipe was set up considering the beam mode and Morison’s nonlinear fluid loads as well as the vortex-excited loads. The approach of calculating vortex-excited nonlinear vibration by Galerkin’s method was proposed. The natural vibration frequencies and modes were obtained, and the response including primary resonance induced by current and the composite resonance under combined wave-current for the 170 m long casing pipe in the 160m depth of water were investigated. The results show that the dynamics response of casing pipe obviously increases, and the complicated response behaviors of casing pipe are described under combined wave-current.
文摘-A composite pipeline is defined as a pipeline system composed of one big pipe and one or several small pipes. Based on the theory of wave- current interaction and physical model test, the hydrodynamic characteristics of the submarine composite pipeline in wave-current coexisting field (both regular and irregular waves) are investigated. The so-called "modified diameter method" is used for analyzing the in-fine hydrodynamic coefficients of the composite pipeline, which are well related to KC number. The comparison of test data for regular and irregular waves shows that in the region of 90 】 KC】 20, the results in these two cases can be unified. The effect of water depth is analyzed in details. The relationships between CD, CM and KC , which are based on the results of present research, may be used as a reference in engineering design.
文摘-Based on the extended Morison Equation and model tests, the in-line forces on small square cylinders caused by waves (regular and irregular) and currents are analyzed in detail in this paper. The hydrodynamic coefficient CD and Cu related to KC number and the effect of direction of wave incidence are also given, which can be used in engineering practice.
基金The Program for Scientific Research Start-up Funds of Guangdong Ocean University under contract No.101302/R18001the Fund of Southern Marine Science and Engineering Guangdong Laboratory(Zhanjiang)under contract No.ZJW-2019-08+1 种基金the National Key Research and Development Program of China under contract No.2016YFC1401403the National Natural Science Foundation of China under contract Nos 41476009 and 41776034
文摘Wave-current interaction and its effects on the hydrodynamic environment in the Beibu Gulf(BG) have been investigated via employing the Coupled Ocean–Atmosphere–Wave–Sediment Transport(COAWST) modeling system. The model could simulate reasonable hydrodynamics in the BG when validated by various observations.Vigorous tidal currents refract the waves efficiently and make the seas off the west coast of Hainan Island be the hot spot where currents modulate the significant wave height dramatically. During summer, wave-enhanced bottom stress could weaken the near-shore component of the gulf-scale cyclonic-circulation in the BG remarkably, inducing two major corresponding adjustments: Model results reveal that the deep-layer cold water from the southern BG makes critical contribution to maintaining the cold-water mass in the northern BG Basin.However, the weakened background circulation leads to less cold water transported from the southern gulf to the northern gulf, which finally triggers a 0.2℃ warming in the cold-water mass area;In the top areas of the BG, the suppressed background circulation reduces the transport of the diluted water to the central gulf. Therefore, more freshwater could be trapped locally, which then triggers lower sea surface salinity(SSS) in the near-field and higher SSS in the far-field.
文摘—In this paper the parabolic approximation model based on mild-slope equation is used tostudy wave propagation over a slowly varying and frictional topography under wave-current interaction.A governing equation considering the friction effects is derived by the authors for the first time.A simpli-fied form for the rate of wave energy dissipation is presented on the basis of the wave-current action conser-vation equation and the bottom friction model given by Yoo and O'connor(1987).Examples reveal thatthe present computational method can be used for the calculation of wave elements for actual engineeringprojects with large water areas.
基金Supported by the National Natural Science Foundation of China(Nos.U1706216,41976010,42006027,U1806227)the Natural Science Foundation of Shandong Province,China(No.ZR2016DQ16)+2 种基金the Key Deployment Project of Center for Ocean Mega-Science,Chinese Academy of Sciences(Nos.COMS2019J02,COMS2019J05)the Chinese Academy of Sciences Strategic Priority Project(Nos.XDA19060202,XDA19060502)the National Key Research and Development Program of China(No.2016YFC1402000)。
文摘We examined the influences of the wind fi eld and wave-current interaction(WCI)on the numerical simulation results of typhoon-induced wind waves in the northern East China Sea(NECS)using the coupled Simulating Waves Nearshore+Advanced Circulation(SWAN+ADCIRC)model.The simulations were performed during two typhoon events(Lekima and Muifa),and two widely used reanalysis wind fields,the Climate Forecast System Version 2(CFSv2)from the National Centers for Environmental Prediction(NCEP)and the fifth-generation European Centre for Medium-Range Weather Forecasts(ECMWF)Reanalysis(ERA5),were compared.The results indicate that the ERA5 and CFSv2 wind fields both reliably reproduced the wind variations measured by in-situ buoys,and the accuracy of the winds from ERA5 were generally better than those from CFSv2 because CFSv2 tended to overestimate the wind speed and the simulated significant wave height(SWH),particularly the peak SWH.The WCI effects between the two wind field simulations were similar;these effects enhanced the SWH throughout the nearshore NECS during both typhoons but suppressed the SWH on the right side of the Typhoon Muifa track in the deep and off shore sea areas.In summary,variations in the water depth and current propagation direction dominate the modulation of wave height.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.52025112 and 51861130358)the State Key Laboratory of Ocean Engineering+1 种基金China(Shanghai Jiao Tong University)(Grant No.1905)the Newton Advanced Fellowships(Grant No.NAF\R1\180304)by the Royal Society。
文摘Coastal wave energy resources have enormous exploitation potential due to shorter weather window,closer installation distance and lower maintenance cost.However,impact loads generated by depth variation from offshore to nearshore and wave-current interaction,may lead to a catastrophic damage or complete destruction to wave energy converters(WECs).This objective of this paper is to investigate slamming response of a coastal oscillating wave surge converter(OWSC)entering or leaving water freely.Based on fully nonlinear potential flow theory,a time-domain wave-current-structure interaction model combined with higher-order boundary element method(HOBEM),is developed to analyze the coupled hydrodynamic problem.The variable-depth seabed is considered in the model to illustrate the shallow water effect on impact loads and free surface profiles in coastal zone.A domain decomposition approach is utilized to simulate the overlapping phenomenon generated by a jet falling into water under gravity effect.Through a series of Lagrangian interpolation methods,the meshes on boundaries are rearranged to avoid the mismatch between element size on free surface and body surface.The present model is validated against the existing experimental and numerical results.Simulations are also provided for the effects of wave-current interaction and uneven local seabed on the slamming responses.It is found that the length of the splash jet increases for a following current and decreases for an opposing current,and that the slamming response of the OWSC device is sensitive to the geometric features of the uneven seabed.
文摘- The wave-current forces on vertical piles in side-by-side arrangement induced by irregular waves with opposing current are investigated experimentally in this paper. The characteristics in both time and frequency domain of in-line, lift and resultant forces are analyzed. The grouping effect coefficients of inline, lift and resultant forces on piles related to KC number and relative spacing parameters are given. These results are compared with those in the case of irregular waves combined with following currents. It is found that the results in these two cases are quite different. The range of KC number tested is 10- 60, the range of Reynolds number is (0.55-3.43) ×104.
文摘- A composite pipeline is defined as a main big pipe composed of one or several small pipes. The flow behaviour around a submarine composite pipeline is more complicated than that around a single submarine pipeline. A series model test of composite pipelines in a wave-current coexisting field was conducted by the authors. Both in-line and lift forces were measured, and the resultant forces were also analyzed. The results of lift forces and resultant forces are reported in this paper. It is found that the lift force coefficients for composite pipelines are well related to the KC number. The lift force coefficients for an irregular wave-current coexisting field are smaller than those for a regular wave-current coexisting field. The frequency of lift force is usually twice the wave frequency or higher. The authors test indicates that the resultant forces are about 10 to 20 percent larger than in-line forces (horizontal forces). The effect of water depth is analyzed. Finally, the relationship between lift
基金supported by the National Key Research and Development Program of China(Grant No.2017YFC1404200)the National Natural Science Foundation of China(Grant No.51479053)the Marine Renewable Energy Research Project of the State Oceanic Administration(Grant No.GHME2015GC01).
文摘Pile foundations have been widely used in offshore engineering.In this study,a three-dimensional numerical model was used to investigate the seabed response around a mono-pile under wave-current loading.Reynolds-averaged Navier-Stokes equations were used to simulate the flow field,and Biot's consolidation equations were used for simulating the response of a porous seabed.The pore water pressure within soil and the effective stress along the depth of the seabed were simulated for various current velocities,with currents traveling either along or against the wave.Results indicate that the current has a significant effect on the effective stress and the pore water pressure distributions,which increases with the current velocity,and that the current traveling against the wave increases the liquefaction depth of the porous seabed.
基金financially supported by the National Natural Science Foundation of China(Grant No.51861130358,51609109)the State Key Laboratory of Ocean Engineering,China(Shanghai Jiao Tong University)(Grant No.1905)+1 种基金the Newton Advanced Fellowships of the Royal Societythe Postgraduate Research&Practice Innovation Program of Jiangsu Province(Grant No.KYCX20_3153)。
文摘The nonlinear dynamic response induced by the wave-current interaction on a deepwater steep wave riser(SWR)is numerically investigated based on a three-dimensional(3 D)time-domain finite element method(FEM).The governing equation considering internal flow is established in the global coordinate system.The whole SWR consists of three segments:the decline segment,buoyancy segment and hang-off segment,in which the buoyancy segment is wrapped by several buoyancy modules in the middle section,leading to the arch bend and sag bend.A Newmark-β iterative scheme is adopted for the accurate analysis to solve the governing equation and update the dynamic response at each time step.The proposed method is verified through the published results for the dynamic response of steel catenary riser(SCR)and static configuration of steel lazy wave riser(SLWR).Simulations are executed to study the influence of wave height,current velocity/direction,internal flow density/velocity and top-end pressure on the tension,configuration and bending moment of the SWR.The results indicate that the influence of the current on the configuration and mechanical behavior of the SWR is greater than that of the wave,especially in the middle section.With increasing current velocity,the suspending height of the middle section drops,meanwhile,its bending moment decreases accordingly,but the tension increases significantly.For a fixed external load,the increasing internal flow density induces the amplification of the tension at the hang-off segment and the mitigation at the decline segment,while the opposite trend occurs at the bending moment.
基金The Program of International S&T Cooperation under contract No.2010DFA24470the National Science Foundation of China under contract No.41376101the Guangdong Provincial Science and Technology Planning Project under contract Nos 2012A030200002 and 2011B031100008
文摘On the basis of the measurement data pertaining to waves, current, and sediment in February 2012 in the mouth bar of the Modaomen Estuary, the Soulsby formulae with an iterative method are applied to calculating bottom shear stresses(BSS) and their effect on a sediment re-suspension. Swell- induced BSS have been found to be the most important part of the BSS. In this study, the correlation coefficient between a wavecurrent shear stress and SSC is 0.86, and that between current shear stresses and SSC is only 0.40. The peaks of the SSC are consistent with the height and the BSS of the swell. The swell is the main mechanism for the sediment re-suspension, and the tidal current effect on sediment re-suspension is small. The peaks of the SSC are centered on the high tidal level, and the flood tide enhances the wave shear stresses and the SSC near the bottom. The critical shear stress for sediment re-suspension at the observation station is between 0.20 and 0.30 N/m2. Tidal currents are too weak to stir up the bottom sediment into the flow, but a WCI(wave-current interaction) is strong enough to re-suspend the coarse sediment.
基金This researchis supported by Research Fund for Doctoral Programs of Higher Education (Grant No.20030141006) ,and a Program for Changjiang Scholars and Innovative Research Teams in Universities (Grant No.IRT0420)
文摘A higher order boundary element method (HOBEM) is implemented for wave-current action on structures. The free-term coefficient and Cauchy principal value (CPV) integrals are computed by direct methods. Numerical experiments are carried out to validate the computation of free-term coefficient and CPV integrals. The results show that the computation precision of free-term coefficient is very high for various bodies, even with edges and corners, and the convergence speed is fast for CPV integrals for different meshes. The comparison of the second order mean drift force due to wave-current action on a uniform cylinder is made with an analytic solution. It is found that good agreement exists between the present calculation and the analytic solutions. Finally, the numerical code is applied for computing wave-current action on Snorre TLP.
基金financially supported by the National Natural Science Foundation of China(Grant No.51309158)funds from the National Key Scientific Instrument and Equipment Development Project(Grant No.2013YQ04091108)Important and Large Scientific and Technical Project of the Ministry of Communications(Grant No.201132874640)
文摘The movement of sediment in estuary and on coast is directly restricted by the bed shear stress. Therefore, the research on the basic problem of sediment movement by the bed shear stress is an important way to research the theory of sediment movement. However, there is not a measuring and computing method to measure the bed shear stress under a complicated dynamic effect like wave and current. This paper describes the measurement and test research on the bed shear stress in a long launder of direct current by the new instrument named thermal shearometer based on micro-nanotechnology. As shown by the research results, the thermal shearometer has a high response frequency and strong stability. The measured results can reflect the basic change of the bed shear stress under wave and wave?current effect, and confirm that the method of measuring bed shear stress under wave?current effect with thermal shearometer is feasible. Meanwhile, a preliminary method to compute the shear stress compounded by wave?current is put forward according to the tested and measured results, and then a reference for further study on the basic theory of sediment movement under a complicated dynamic effect is provided.
基金Supported by the National Basic Research Program(973Program)(Nos.2007CB816001,2005CB422302,2005CB422307and2007CB411806)the National Natural Science Foundation of China(Nos.41030854,40776016,40906015,and40906016)+1 种基金the Major Project of National Natural Science Foundation of China(Nos.40490263,40976005)the Research Project of National Marine Data and Information Service(No.29106006C)
文摘We investigated the Stokes drift-driven ocean currents and Stokes drift-induced wind energy input into the upper ocean using a two-way coupled wave-current modeling system that consists of the Princeton Ocean Model generalized coordinate system (POMgcs), Simulating WAves Nearshore (SWAN) wave model, and the Model Coupling Toolkit (MCT). The Coriolis-Stokes forcing (CSF) computed using the wave parameters from SWAN was incorporated with the momentum equation of POMgcs as the core coupling process. Experimental results in an idealized setting show that under the steady state, the scale of the speed of CSF-driven current was 0.001 m/s and the maximum reached 0.02 m/s. The Stokes drift-induced energy rate input into the model ocean was estimated to be 28.5 GW, taking 14% of the direct wind energy rate input. Considering the Stokes drift effects, the total mechanical energy rate input was increased by approximately 14%, which highlights the importance of CSF in modulating the upper ocean circulation. The actual run conducted in Taiwan Adjacent Sea (TAS) shows that: 1) CSF-based wave-current coupling has an impact on ocean surface currents, which is related to the activities of monsoon winds; 2) wave-current coupling plays a significant role in a place where strong eddies present and tends to intensify the eddy's vorticity; 3) wave-current coupling affects the volume transport of the Taiwan Strait (TS) throughflow in a nontrivial degree, 3.75% on average.
基金supported by the National Natural Science Foundation of China (No. 51178397)Technological Research and Development Programs of the Ministry of Railways (No. 2010G004-L)
文摘Large eddy simulation is performed to study three-dimensional wave-current interaction with a square cylinder at different Reynolds numbers, ranging from 1,000 to 600,000. The Keulegan-Carpenter number is relevantly a constant of 0.6 for all cases. The Strouhal number, the mean and the RMS values of the effective drag coefficient in the streamwise and transverse directions are computed for various Reynolds numbers, and the velocity of a representative point in the turbulent zone is simulated to find the turbulent feature. It is found that the wave-current interaction should be considered as three-dimensional flow when the Reynolds number is high; under wave-current effect, there exists a critical Reynolds number, and when the Reynolds number is smaller than the critical one, current effect on wave can be nearly neglected; conversely, with the Reynolds number increasing, wave-current- structure interaction is sensitive to the Reynolds number.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.51061130546 and 51379127)the Key Projects in the National Science&Technology Pillar Program(Grant No.2012BAC07B02)
文摘In order to study the mechanism of flow-sediment movement, it is essential to obtain measured data of water hydrodynamic and sediment concentration process with high spatial and temporal resolution in the bottom boundary layer(BBL). Field observations were carried out in the northwest Caofeidian sea area in the Bohai Bay. Near 2 m isobath(under the lowest tidal level), a tripod system was installed with AWAC(Acoustic Wave And Current), ADCP(Acoustic Doppler Current Profilers), OBS-3A(Optical Backscatter Point Sensor), ADV(Acoustic Doppler Velocimeters), etc. The accurate measurement of the bottom boundary layer during a single tidal period was carried out, together with a long-term sediment concentration measurement under different hydrological conditions. All the measured data were used to analyze the characteristics of wave-current-sediment movement and the BBL. Analysis was performed on flow structure, shear stress, roughness, eddy viscosity and other parameters of the BBL. Two major findings were made. Firstly, from the measured data, the three-layer distribution model of the velocity profiles and eddy viscosities in the wave-current BBL are proposed in the observed sea area; secondly, the sediment movement is related closely to wind-waves in the muddy coast area where sediment is clayey silt: 1) The observed suspended sediment concentration under light wind conditions is very low, with the peak value generally smaller than 0.1 kg/m3 and the average value being 0.03 kg/m3; 2) The sediment concentration increases continuously under the gales over 6-7 in Beaufort scale, under a sustained wind action. The measured peak sediment concentration at 0.4 m above the seabed is 0.15-0.32 kg/m3, and the average sediment concentration during wind-wave action is 0.08-0.18 kg/m3, which is about 3-6 times the value under light wind conditions. The critical wave height signaling remarkable changes of sediment concentration is 0.5 m. The results show that the suspended load sediment concentration is mainly influenced by wave-induced sediment suspension.
基金Supported by the National Key Research and Development Program of China(No.2016YFC1402000)the National Natural Science Foundation of China(Nos.41376027,U1133001,41606024)+3 种基金the National Program on Global Change and Air-Sea Interaction(No.GASI-IPOVAI-01-06)the NSFC-Shandong Joint Fund for Marine Science Research Centers(No.U1406401)the NSFC Innovative Group Grant Project(No.41421005)the High Performance Computing Environment Qingdao Branch of Chinese Academy of Science(CAS)
文摘The northern South China Sea(SCS) is frequently affected by typhoons. During severe storm events, wave-current interactions produce storm surges causing enormous damage in the path of the typhoon. To evaluate the influence of wave-current interactions on storm surge, we used a coupled ocean-atmospherewave-sediment transport(COAWST) modeling system with radiation-stress and vortex-force formulations to simulate two typically intense tropical storms that invaded the SCS, namely Typhoons Nuri(2008) and Hagupit(2008), and compared results with observations from the Hong Kong Observatory. Both radiationstress and vortex-force formulations significantly improved the accuracy of the simulation. Depending on which typhoon and the topography encountered, the influence of surface waves on the oceanic circulation showed different characteristics, including the differences of range and intensity of storm surge between vortex-force and radiation-stress experiments. During typhoon landing, strong sea-surface elevation in concert with wave set-up/set-down caused the adjustment of the momentum balance. In the direction perpendicular to the current, but especially in the cross-shore direction, the pressure gradient and wave effects on the current dominated the momentum balance.
基金supported by the National Natural Science Foundation of China(41176073)
文摘This letter presents a new analytical approximation for wave (current)-induced dynamic soil response in marine sediments. In the model, the third-order approximation for wave-current interactions is employed for the flow model, while Biot's dynamic poro-elastic model is used to simulate the porous flow in a seabed. The newly analytical solution is validated with the field observations. Based on the solution, effects of currents and wave-nonlinearity on soil response are examined and a parametric study will be carried out to examine the influence of currents onthe liquefaction potential.