32 results on '"Aifeng Tao"'
Search Results
2. A method for estimating the risk of fishery ports against typhoon: a case study on Dongsha fishery port
- Author
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Zhang Yachao, Yanfen Deng, Aifeng Tao, Jianfeng Wang, Huang Wentao, jufei qiu, Xiaojie Zhang, and Jianli Zhao
- Subjects
Fishery ,Environmental Engineering ,Typhoon ,Environmental science ,Environmental Chemistry ,Safety, Risk, Reliability and Quality ,Port (computer networking) ,General Environmental Science ,Water Science and Technology - Abstract
After standard seawalls have been built successfully, fishery ports become the structures most easily damaged during a typhoon. Estimating the risk of fishery ports against typhoons would be useful for identifying weaknesses and implementing corrective measures to protect fishing boats from a typhoon. This study describes a versatile methodology for conducting this type of quantitative assessment at fishery ports. The Dongsha fishery port in Zhejiang Province was selected as a case study to test the results derived from a high-precision Hydrodynamic Flexible Mesh model coupled with the Spectral Wave model. First, typhoon characteristics were assessed based on historical typhoons in the study area, and then, the wind, tide, storm surge, and waves were modeled and tide-surge interactions were investigated. Through comparisons of the destructive parameters from the typhoon assessment with the design and structural parameters of the fishery port, the level of the Dongsha fishery port against typhoons was determined to be 12, and the main weaknesses of the port’s defenses were found to be located near feature points T2, T3, T8, and T15. The results obtained demonstrate that the proposed methodology can be used to acquire valuable information on the risk of fishery ports against typhoons.
- Published
- 2022
3. An Effective Significant Wave Height Prediction Method Based on EMD-Wavenet Network
- Author
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Tao lv, Aifeng Tao, Zhang Zhen, and Gang Wang
- Published
- 2023
4. Practices and Prospects of the Synergy between Coastal Ecology and Disaster Mitigation in China
- Author
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Jinhai Zheng, Wei Xu, Aifeng Tao, Jun Fan, Jinyang Xing, and Gang Wang
- Published
- 2023
5. Experimental study on time-varying failure evolution of armour blocks on sloping breakwaters
- Author
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Aifeng Tao, Wei Xu, Jinrui Si, Songgui Chen, Hongbo Zhao, and Gang Wang
- Subjects
Environmental Engineering ,Ocean Engineering - Published
- 2023
6. Numerical Investigation on Temporal Evolution Behavior for Triad Resonant Interaction Induced by Steady Free-Surface Flow over Rippled Bottoms
- Author
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Jun Fan, Aifeng Tao, Jinhai Zheng, and Ji Peng
- Subjects
Ocean Engineering ,triad resonant interaction ,numerical simulation ,high-order spectral method (HOS) ,free-surface flow ,temporal instability ,Water Science and Technology ,Civil and Structural Engineering - Abstract
Investigating the wave hydrodynamics of free-surface flow over rippled bottoms is a continuing concern due to the existence of submarine multiple sandbars and ambient flow in coastal and estuarial areas. More attention to free-surface wave stimulation has been received from the perspective of resonant wave-wave interaction, which is an intensive way for wave energy transfer and a potential way for wave component generation. However, the basic behavior of the triad resonant interaction of this problem is still limited and unclear. In this study, the triad resonant interaction induced by steady free-surface flow over rippled bottoms is numerically investigated by means of the High-Order Spectral (HOS) method. By considering the interactions among free-surface waves, ambient current, and rippled bottoms, the numerical model is applied for this situation based on Zakharov equation with ambient flow term. The temporal evolution of the triad resonant wave amplitude has been numerically investigated and compared well with multiple-scale expansion perturbation theory. Specifically, the temporal evolution behaviors of all six triad resonant wave components are confirmed by both numerical simulation and nonlinear perturbation analysis.
- Published
- 2022
- Full Text
- View/download PDF
7. Protect oyster reefs in China’s coastal zone
- Author
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Wei Xu, Aifeng Tao, and Jinhai Zheng
- Subjects
Multidisciplinary - Published
- 2023
8. Analytical investigation of trapped waves over a submerged exponential ridge
- Author
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Gang Wang, Yiwei Zhang, Jinhai Zheng, Ruili Fu, and Aifeng Tao
- Subjects
Environmental Engineering ,Ocean Engineering - Published
- 2023
9. Numerical investigation on nonlinear evolution behavior and water particle velocity of wave crests for narrow-band wave field with Gaussian spectrum
- Author
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Jun Fan, Aifeng Tao, Shuya Xie, Di Wu, and Gang Wang
- Subjects
Environmental Engineering ,Ocean Engineering - Published
- 2023
10. Statistical properties of extreme wave groups based on field data
- Author
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Ruili Fu, Jinhai Zheng, Aifeng Tao, and Gang Wang
- Abstract
An extreme wave always evolves from a wave group in random wave trains. Therefore, better insights into extreme wave groups are crucial for the safety design of marine structures. In the present work, the marginal and bivariate distributions of extreme wave group energy and duration are investigated based on the field datasets from Norway's North Sea. The most probable extreme wave group energy and duration can be obtained based on the distributions, then evolutions of wave shapes of extreme wave groups are investigated and compared with the present extreme wave group theories. It is found that the wave shapes are asymmetry with time-spatial evolution.
- Published
- 2022
11. Investigation on Dynamic Response of the Liquid Tank Sloshing in Waves
- Author
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Zhen Zhang, Aifeng Tao, Qiaorui WU, and Yonghe Xie
- Published
- 2022
12. Swell Source Analysis of East China Sea Under the Influence of Typical Typhoon Scenarios
- Author
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Ye Pei, Yi-nan Lin, Ya-yi Liu, Aifeng Tao, Jin Yan, and Su Junwei
- Subjects
South china ,Renewable Energy, Sustainability and the Environment ,Mechanical Engineering ,Fetch ,020101 civil engineering ,Ocean Engineering ,02 engineering and technology ,Oceanography ,01 natural sciences ,Swell ,010305 fluids & plasmas ,0201 civil engineering ,Low energy ,North west ,Climatology ,Typhoon ,0103 physical sciences ,Offshore geotechnical engineering ,Geology ,China sea - Abstract
The characteristics of swells within the East China Sea have been reported by Tao et al. (2017), while the question of where the swells come from remains unanswered. By using the wave model WAVEWATCH III and the swell tracking method proposed by Hanson (2001), the spatial sources of the swells are investigated during four typical typhoon scenarios, which usually affect the wave environment in the East China Sea, including the Recurving type, the Northward type, the Westward type (striking the East China Sea) and the Westward type (over the South China Sea). The numerical results show that parts of the swells are from the North West Pacific with a long-distance travelling. The moving paths of the swells are affected by the typhoon tracks, which result in various fetches. The Westward type (over the South China Sea) makes one peak in the evolution process. The landing process of the Westward type (striking the East China Sea) could result in swells with low energy. The swell energy depends on swell propagation distance, existence time and wind intensity of generation fetch. The consistent fetch and forceful wind intensity make swell carry more energy.
- Published
- 2020
13. The Effects on Water Particle Velocity of Wave Peaks Induced by Nonlinearity under Different Time Scales
- Author
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Yini Yang, Di Wu, Shuya Xie, Aifeng Tao, and Jun Fan
- Subjects
010504 meteorology & atmospheric sciences ,Naval architecture. Shipbuilding. Marine engineering ,VM1-989 ,Ocean Engineering ,GC1-1581 ,Deformation (meteorology) ,Oceanography ,01 natural sciences ,Instability ,010305 fluids & plasmas ,deformation degree ,0103 physical sciences ,Wave height ,Initial value problem ,Stokes wave ,water particle velocity of the wave peaks ,Rogue wave ,0105 earth and related environmental sciences ,Water Science and Technology ,Civil and Structural Engineering ,Physics ,modulation instability ,nonlinearity ,Mechanics ,Exponential function ,Stage (hydrology) ,high-order spectral method - Abstract
The water particle velocity of the wave peaks is closely related to the wave load borne by offshore structures. It is of great value for marine disaster prevention to study the water particle velocity of nonlinear extreme waves represented by Freak waves. This study applies the High-order Spectral Method (HOS) numerical model to analyze the characteristics and influencing factors of the water particle velocity of Freak wave peak with two different generation mechanisms under the initial condition of a weakly modulated Stokes wave train. Our results show that the water particle velocity of the wave peak increases linearly with wave height and initial wave steepness in the evolution stage of modulation instability. While in the later stage, the relationship becomes exponential. Under the condition of similar wave heights, the deformation degrees of Freak waves with different generation mechanisms are distinct, the deformation degree of modulation instability stage is smaller than that of the later stage. The water particle velocity of the wave peaks increases with the deformation degrees. Furthermore, the correlation between wave peak height and water particle velocity is a quadratic function. This provides a theoretical basis for further understanding of nonlinear waves and the prediction of marine disasters.
- Published
- 2021
14. Experimental Investigation on Bragg Resonant Reflection of Waves by Porous Submerged Breakwaters on a Horizontal Seabed
- Author
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Wei Xu, Chun Chen, Min Han Htet, Mohammad Saydul Islam Sarkar, Aifeng Tao, Zhen Wang, Jun Fan, and Degang Jiang
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Geography, Planning and Development ,Aquatic Science ,Biochemistry ,Bragg resonance ,reflection coefficient ,porous submerged breakwaters ,horizontal seabed ,flume experiments ,Water Science and Technology - Abstract
Submerged breakwaters based on Bragg resonance could be one of the measures used for mitigating marine disasters and coastal erosion in nearshore areas. Here, flume experiments were conducted to investigate the Bragg resonant reflection of waves propagating over porous submerged breakwaters. Furthermore, the influence of permeability, relative width, relative height, and section shapes of submerged breakwaters on Bragg resonant reflection were considered. This revealed that the Bragg resonant reflection coefficient increased with the decrease in permeability and increase in the relative height of submerged breakwaters. However, a slowing trend occurred when the Bragg resonant reflection coefficient peak decreased with the increase in permeability and increased with the increase in relative height. Moreover, the primary peak Bragg resonance increased with the increase in the relative width of submerged breakwaters in the range of 0.1–0.3. This was consistent with the numerical results of Ni and Teng (2021), to a certain extent, as the reflection coefficient first increased and then decreased with the relative bar width. In addition, rectangular submerged breakwaters demonstrated a better reflection effect than the trapezoidal submerged breakwaters, and the triangular submerged breakwaters demonstrated a poor reflection effect.
- Published
- 2022
15. Intraseasonal Variability of Sea Level in the Western North Pacific
- Author
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Aifeng Tao, Haolang Liu, Wei Zhang, and Xiangbo Feng
- Subjects
South china ,010504 meteorology & atmospheric sciences ,Atmospheric pressure ,Propagation pattern ,Tropics ,Madden–Julian oscillation ,Oceanography ,01 natural sciences ,Geophysics ,Space and Planetary Science ,Geochemistry and Petrology ,Satellite altimetry ,Climatology ,Earth and Planetary Sciences (miscellaneous) ,Boreal summer ,Geology ,Sea level ,0105 earth and related environmental sciences - Abstract
Sea levels in the Western North Pacific (WNP) are presented with anomalous intraseasonal variations. This study examines the response of sea level in the WNP to the atmospheric Intraseasonal Oscillation modes, namely the Madden-Julian Oscillation (MJO) and the Boreal Summer Intraseasonal Oscillation (BSISO), using the 25 years (1993-2017) of satellite altimetry and barotropic model output. In winter, the MJO has significant effects on the component of sea level due to the instant wind and atmospheric pressure effects (high-frequency), showing an eastward propagation pattern in most regions, with the strongest effects in the western marginal seas. The MJO-associated pattern of dynamical (low-frequency) component of sea level propagates southward, with the significant effects mostly in the tropics. In summer, the BSISO-associated pattern of the high-frequency component of sea level moves from southwest to northeast, with the largest anomalies in the middle of WNP (20{degree sign}N-30{degree sign}N), while the strongest BSISO effects on the low-frequency component are detectable mostly in the coasts of China and east of the Philippines. The MJO and BSISO can also modulate the probability of extreme sea level events. In winter, during phases 2-5, MJO increases the chance of extreme high events in the high-frequency component of sea level by 100-200% in the western coasts and the tropics. In summer, in BSISO phases 6-7, the chance of extreme high events in the high-frequency component of sea level is enhanced by >300% in the South China Sea and east of the Philippines.
- Published
- 2021
16. Intraseasonal variability of sea level in the Western North Pacific
- Author
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Haolang Liu, Xiangbo Feng, Aifeng Tao, and wei Zhang
- Abstract
Sea levels in the Western North Pacific (WNP) are presented with anomalous intraseasonal variations. This study examines the response of sea level in the WNP to the atmospheric Intraseasonal Oscillation modes, namely the Madden-Julian Oscillation (MJO) and the Boreal Summer Intraseasonal Oscillation (BSISO), using the 25 years (1993-2017) of satellite altimetry and barotropic model output. In winter, the MJO has significant effects on the component of sea level due to the instant wind and atmospheric pressure effects (high-frequency), showing an eastward propagation pattern in most regions, with the strongest effects in the western marginal seas. The MJO-associated pattern of dynamical (low-frequency) component of sea level propagates southward, with the significant effects mostly in the tropics. In summer, the BSISO-associated pattern of the high-frequency component of sea level moves from southwest to northeast, with the largest anomalies in the middle of WNP (20{degree sign}N-30{degree sign}N), while the strongest BSISO effects on the low-frequency component are detectable mostly in the coasts of China and east of the Philippines. The MJO and BSISO can also modulate the probability of extreme sea level events. In winter, during phases 2-5, MJO increases the chance of extreme high events in the high-frequency component of sea level by 100-200% in the western coasts and the tropics. In summer, in BSISO phases 6-7, the chance of extreme high events in the high-frequency component of sea level is enhanced by >300% in the South China Sea and east of the Philippines.
- Published
- 2021
17. Evaluation of the resilience of fishery ports to typhoons: a case study on Dongsha fishery port
- Author
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Jianfeng Wang, Huang Wentao, jufei qiu, Zhang Yachao, Yanfen Deng, Jianli Zhao, Aifeng Tao, and Xiaojie Zhang
- Subjects
Fishery ,Wave model ,Typhoon ,Fishing ,Quantitative assessment ,Environmental science ,Storm surge ,Resilience (network) ,Port (computer networking) ,Mesh model - Abstract
After standard seawalls have been built successfully, fishery ports become the structures most easily damaged during a typhoon. Assessments of the resilience of fishery ports to typhoon damage would be useful for identifying weaknesses and implementing corrective measures to protect fishing boats from a typhoon. This study describes a versatile methodology for conducting this type of quantitative assessment at fishery ports. The Dongsha fishery port in Zhejiang Province was selected as a case study to test the results derived from a high-precision Hydrodynamic Flexible Mesh model coupled with the Spectral Wave model. First, typhoon characteristics were assessed based on historical typhoons in the study area, and then, the wind, tide, storm surge, and waves were modeled and tide-surge interactions were investigated. Through comparisons of the destructive parameters from the typhoon assessment with the design and structural parameters of the fishery port, the resistance level of the Dongsha fishery port against typhoons was determined to be 12, and the main weaknesses of the port's defenses were found to be located near feature points T2, T3, T8, and T15. The results obtained demonstrate that the proposed methodology can be used to acquire valuable information on the resilience of fishery ports to typhoons.
- Published
- 2021
18. Upstream-propagating waves induced by steady current over a rippled bottom: theory and experimental observation
- Author
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Aifeng Tao, Yuming Liu, Jinhai Zheng, and Jun Fan
- Subjects
Physics ,Mechanical Engineering ,Ripple ,Resonance ,02 engineering and technology ,Mechanics ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,010305 fluids & plasmas ,Physics::Fluid Dynamics ,Amplitude ,Wave flume ,Mechanics of Materials ,0103 physical sciences ,Wavenumber ,Group velocity ,Current (fluid) ,0210 nano-technology ,Choked flow - Abstract
We theoretically and experimentally investigate the mechanism underlying the generation of upstream-propagating waves induced by a steady current over a horizontal bottom with a patch of sinusoidal ripples. By considering the triad resonant wave–ripple interactions involving two unsteady wave components (which have the same frequency but different wavenumbers) and one bottom ripple component in the presence of a steady uniform current, we derive the general condition under which unsteady upstream- and/or downstream-propagating waves can be induced. The frequency and wavenumbers of the induced propagating waves are given by the triad resonance condition in terms of current speed, water depth and bottom ripple wavenumber. By means of a multiple-scale perturbation analysis, we obtain the nonlinear amplitude evolution equations governing the spatio-temporal evolution of resonance-generated waves. Based on these equations, we find that the amplitude of the generated upstream-propagating waves is dramatically amplified when the associated triad resonance occurs in the neighbourhood of the critical current speed/frequency (corresponding to zero group velocity of unsteady waves in the presence of a current). A series of laboratory experiments in a long wave flume with wide ranges of current speeds and water depths are conducted to verify the theory. The experiments confirm the observation of the phenomenon of upstream-propagating wave generation in a steady flow over a rippled bottom. In particular, the experimental measurements of the kinematics of upstream-propagating waves as well as the critical flow condition for the observation of such wave generation compare well with the theoretical prediction.
- Published
- 2021
19. An analytic investigation of primary and cross waves in the flume with a shoal
- Author
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Gang Wang, Ying Yu, Aifeng Tao, and Jinhai Zheng
- Subjects
Environmental Engineering ,Ocean Engineering - Published
- 2022
20. Experimental study on mechanism of sea-dike failure due to wave overtopping
- Author
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Gang Chen, Aifeng Tao, Jinhai Zheng, Weixuan Yang, Xinping Chen, Yao Zhang, and Jinchun Hu
- Subjects
Dike ,geography ,geography.geographical_feature_category ,010504 meteorology & atmospheric sciences ,business.industry ,Rubble ,Hazard mitigation ,Ocean Engineering ,Fatigue damage ,engineering.material ,01 natural sciences ,010305 fluids & plasmas ,Shear (geology) ,0103 physical sciences ,engineering ,Failure risk ,Geotechnical engineering ,Sea dike ,business ,0105 earth and related environmental sciences ,Swash - Abstract
This work, which was largely a fruit of China's national marine hazard mitigation service, explicitly reveals the major mechanism of sea-dike failure during wave overtopping. A large group of wave-flume experiments were conducted for sea dikes with varying geometric characteristics and pavement types. The erosion and slide of the landward slope due to the combined effect of normal hit and great shear from overtopping flows was identified the major trigger of the destabilization of sea dikes. Once the intermittent hydrodynamic load and swash caused any deformation (bump or dent) of the pavement layer, pavement fractions (slabs or rubble) on the slope started to be initiated and removed by the water. The erosion of the landward slope was then gradually aggravated followed by entire failure within a couple of minutes. Hence, the competent velocity would be helpful evaluate the failure risk if as well accounted in standards or criteria. However, the dike top was measured experiencing the largest hydrodynamic pressure with a certain cap while the force on the wall increased rapidly as the overtopping intensity approached the dike-failure threshold. The faster increase of the force on the wall than on the landward slope yielded the sequencing of loads reaching hypothetic limits before failure as: dike top – top-mounted wall – landward slope. Therefore, beside the slide failure, the fatigue damage due to the instantaneous hydrodynamic impact might be another mechanism of the dike failure, which did not appear in the experiment but should be kept in mind. Instead of the widely adopted tolerable overtopping rate, a 0.117–0.424 m3/(m s) range of overtopping discharge and a 10 m/s overtopping velocity for the failure risk of typical sea dikes along China's coastlines were suggested, which enables the possible failure risk prediction through empirical calculations. The failure overtopping rate was identified strongly dependent on the pavement material, the landward slope and the dike-mounted wall but showed little variation with the width of the dike top. The flat concrete pavement and gentle landward slopes are suggested for the dike design and construction. For given configurations and hydrodynamic conditions in the experiment, the dike without the wall experienced less overtopping volume than those with the 1-m top-mounted wall. Meanwhile, the remove of the wall increased the failure overtopping rate, which means a certain increase of the failure criterion. Thus, care must be taken to conclude that the dike-mounted wall seems not an entirely appropriate reinforcement for the stability and safety of coastal protections. This should be further checked and discussed by researchers and engineers in the future.
- Published
- 2017
21. Wave power focusing due to the Bragg resonance
- Author
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Wang Yi, Jinhai Zheng, Chuan Qin, Aifeng Tao, Jun Fan, and Jin Yan
- Subjects
Physics ,Renewable Energy, Sustainability and the Environment ,business.industry ,020209 energy ,Mechanical Engineering ,Surface acoustic wave ,Plane wave ,Ocean Engineering ,Transverse wave ,02 engineering and technology ,Oceanography ,01 natural sciences ,010305 fluids & plasmas ,Standing wave ,Optics ,Cross-polarized wave generation ,Surface wave ,0103 physical sciences ,0202 electrical engineering, electronic engineering, information engineering ,Energy transformation ,business ,Wave power - Abstract
Wave energy has drawn much attention as an achievable way to exploit the renewable energy. At present, in order to enhance the wave energy extraction, most efforts have been concentrated on optimizing the wave energy convertor and the power take-off system mechanically and electrically. However, focusing the wave power in specific wave field could also be an alternative to improve the wave energy extraction. In this experimental study, the Bragg resonance effect is applied to focus the wave energy. Because the Bragg resonance effect of the rippled bottom largely amplifies the wave reflection, leading to a significant increase of wave focusing. Achieved with an energy conversion system consisting of a point absorber and a permanent magnet single phase linear motor, the wave energy extracted in the wave flume with and without Bragg resonance effect was measured and compared quantitatively in experiment. It shows that energy extraction by a point absorber from a standing wave field resulted from Bragg resonance effect can be remarkably increased compared with that from a propagating wave field (without Bragg resonance effect).
- Published
- 2017
22. Swells of the East China Sea
- Author
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Nobuhito Mori, Jin Yan, Jinhai Zheng, Aifeng Tao, and Ye Pei
- Subjects
021110 strategic, defence & security studies ,010504 meteorology & atmospheric sciences ,Global warming ,0211 other engineering and technologies ,Ocean Engineering ,02 engineering and technology ,Oceanography ,01 natural sciences ,Swell ,Marine safety ,North west ,Climatology ,Typhoon ,Wind wave ,Hindcast ,Geology ,0105 earth and related environmental sciences ,China sea - Abstract
Over the past few decades, an increasing number of marine activities have been conducted in the East China Sea, including the construction of various marine structures and the passage of large ships. Marine safety issues are paramount and are becoming more important with respect to the likely increase in size of ocean waves in relation to global climate change and associated typhoons. In addition, swells also can be very dangerous because they induce the resonance of floating structures, including ships. This study focuses on an investigation of swells in the East China Sea and uses hindcast data for waves over the past 5 years in a numerical model, WAVEWATCH III (WW3), together with historical climate data. The numerical calculation domain covers the entire North West Pacific. Next, swells are separated and analyzed using simulated wave fields, and both the characteristics and generation mechanisms of swells are investigated.
- Published
- 2017
23. Experimental Study on Upstream-Advancing Waves Induced by Currents
- Author
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Jinhai Zheng, Wang Yi, Aifeng Tao, Yu Haofeng, and Jun Fan
- Subjects
geography ,geography.geographical_feature_category ,Ecology ,Submarine ,Shoal ,01 natural sciences ,010305 fluids & plasmas ,010101 applied mathematics ,Current (stream) ,Oceanography ,Free surface ,0103 physical sciences ,Upstream (networking) ,0101 mathematics ,Geology ,Critical condition ,Earth-Surface Processes ,Water Science and Technology - Abstract
Fan, J.; Zheng, J.; Tao, A.; Yu, H, and Wang, Y, 2016. Experimental study on upstream-advancing waves induced by currents. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 846–850. Coconut Creek (Florida), ISSN 0749-0208. Due to the widespread existence of large-scale continuous submarine sandbars the coasts and estuaries, the interaction between the ambient current and this kind of topography is important and complicated. It has been known that regular free surface waves can be generated and propagate in the upstream direction, when a steady current with specific depth and velocity flows past the fixed periodic wavy bottoms with large steepness. This particular free surface response, called the upstream-advancing wave, has drawn attention in the past few decades but still lacks detailed quantitative study identifying the critical conditio...
- Published
- 2016
24. Numerical Modeling of Wave Interaction with Double Curtain-wall Breakwater
- Author
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Aifeng Tao, Yuliang Zhu, Yu Li, and Jisheng Zhang
- Subjects
Engineering ,business.industry ,wave transmission coefficient ,numerical wave tank ,General Medicine ,Mechanics ,Dissipation ,Action (physics) ,Breakwater ,Wave shoaling ,revised formula ,Geotechnical engineering ,Transmission coefficient ,Curtain wall ,Numerical wave tank ,business ,Reynolds-averaged Navier–Stokes equations ,double curtain-wall breakwater ,Engineering(all) - Abstract
A numerical wave tank (NWT) based on the RANS equations is established by adding source terms into the momentum equation for generating wave and absorbing the reflected waves effectively. The wave dissipation induced by double curtain-wall breakwater and the flow field nearby under the action of regular wave are simulated. The effects of relative immersed depth of barrier on transmission coefficient are analyzed. The numerical results are identical with the experimental data, while they are different a lot from the results of the Lapa formula. The effects of relative width of horizontal plate, relative depth, wave slope are investigated, and a revised formula is presented based on comprehensive verification with both the experiment and numerical results.
- Published
- 2015
- Full Text
- View/download PDF
25. A preliminary investigation of rogue waves off the Jiangsu coast, China
- Author
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Dong Jiing Doong, Jinhai Zheng, J. Fan, Aifeng Tao, J. Peng, and Y. Wang
- Subjects
General Earth and Planetary Sciences ,Rogue wave ,China ,Seismology ,Geology - Abstract
Due to the potential disasters induced by rogue waves, research in this field has increased rapidly in the last 2 decades. However, there are still a lot of open questions left, including some classic ones, such as whether the rogues waves are just rare events or not. One of the key reasons is that not enough of the observed rogue waves have been investigated. China has a wide sea area, but none of the research has addressed the observed rogue waves. In the present study, 1 year of observed wave data from Jiangsu coastal area, China, are analyzed. It is found that rogue waves are present, although the wave heights are not very large; furthermore, the probability of their occurrence is similar to the Rayleigh distribution prediction, due to the local silty coastal topography. The characteristics of rouge waves are investigated and the results indicate that a new type of rogue wave may exist.
- Published
- 2014
26. Numerical experiments on transverse oscillations induced by normal-incident waves in a rectangular harbor of constant slope
- Author
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Jinhai Zheng, Gang Wang, Aifeng Tao, Jerome P.-Y. Maa, and Jisheng Zhang
- Subjects
Physics ,Environmental Engineering ,Water transport ,Oscillation ,Numerical analysis ,Ocean Engineering ,Transverse wave ,Mechanics ,Physics::Fluid Dynamics ,Nonlinear system ,Transverse plane ,Wind wave ,Geotechnical engineering ,Constant (mathematics) - Abstract
In a rectangular harbor with a constant bottom slope, transverse oscillation may occur. This kind of wave has a maximum amplitude at the dead end of the harbor and decays exponentially in the offshore direction. This numerical investigation, using the nonlinear wave transformation model FUNWAVE 2.0, demonstrates the generation of subharmonic and synchronous transverse oscillations within a harbor induced by waves impacting normally on. The subharmonic transverse oscillations are trivial if the bottom slope is small, while the synchronous transverse oscillations are trivial and irrelevant for the bottom slopes. For checking the system responses, transverse oscillations within the harbor that also has a small bottom slope across the harbor were also examined. The generation of subharmonic oscillation seems not to be affected by a small transverse bottom slope; however, the synchronous transverse oscillations are enhanced significantly.
- Published
- 2013
27. Re-study on recurrence period of Stokes wave train with high order spectral method
- Author
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Mee Soe Mee, Jinhai Zheng, Aifeng Tao, and Botao Chen
- Subjects
Basis (linear algebra) ,Renewable Energy, Sustainability and the Environment ,Mechanical Engineering ,Mathematical analysis ,Ocean Engineering ,Oceanography ,Instability ,Schrödinger equation ,Nonlinear system ,symbols.namesake ,Classical mechanics ,symbols ,Stokes wave ,Rogue wave ,Spectral method ,Period (music) ,Mathematics - Abstract
Owing to the Benjamin-Feir instability, the Stokes wave train experiences a modulation-demodulation process, and presents a recurrence characteristics. Stiassnie and Shemer researched the unstable evolution process and provided a theoretical formulation for the recurrence period in 1985 on the basis of the nonlinear cubic Schrodinger equation (NLS). However, NLS has limitations on the narrow band and the weak nonlinearity. The recurrence period is re-investigated in this paper by using a highly efficient High Order Spectral (HOS) method, which can be applied for the direct phaseresolved simulation of the nonlinear wave train evolution. It is found that the Stiassnie and Shemer’s formula should be modified in the cases with most unstable initial conditions, which is important for such topics as the generation mechanisms of freak waves. A new recurrence period formula is presented and some new evolution characteristics of the Stokes wave train are also discussed in details.
- Published
- 2011
28. New Concept for Assessment of Tidal Current Energy in Jiangsu Coast, China
- Author
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Hui Li, Jinhai Zheng, Jun Wang, Jisheng Zhang, and Aifeng Tao
- Subjects
business.industry ,Mechanical Engineering ,lcsh:Mechanical engineering and machinery ,Renewable energy ,Physics::Geophysics ,Tidal current energy ,Oceanography ,Marine energy ,Energy transformation ,Environmental science ,Geotechnical engineering ,Environmental impact assessment ,lcsh:TJ1-1570 ,Astrophysics::Earth and Planetary Astrophysics ,Predictability ,business ,China ,Tidal power - Abstract
Tidal current energy has attracted more and more attentions of coastal engineers in recent years, mainly due to its advantages of low environmental impact, long-term predictability, and large energy potential. In this study, a two-dimensional hydrodynamic model is applied to predict the distribution of mean density of tidal current energy and to determine a suitable site for energy exploitation in Jiangsu Coast. The simulation results including water elevation and tidal current (speed and direction) were validated with measured data, showing a reasonable agreement. Then, the model was used to evaluate the distribution of mean density of tidal current energy during springtide and neap tide in Jiangsu Coast. Considering the discontinuous performance of tidal current turbine, a new concept for assessing tidal current energy is introduced with three parameters: total operating time, dispersion of operating time, and mean operating time of tidal current turbine. The operating efficiency of tidal current turbine at three locations around radial submarine sand ridges was taken as examples for comparison, determining suitable sites for development of tidal current farm.
- Published
- 2013
29. The Most Unstable Conditions of Modulation Instability
- Author
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Jinhai Zheng, Botao Chen, Soe Mee Mee, and Aifeng Tao
- Subjects
Physics ,Carrier signal ,Article Subject ,Sideband ,business.industry ,Applied Mathematics ,lcsh:Mathematics ,Mean value ,lcsh:QA1-939 ,Instability ,Optics ,Modulation ,Quantum electrodynamics ,Wave field ,Spectral method ,business - Abstract
Modulation instability is one of the most ubiquitous types of instabilities in nature. As one of the key characteristics of modulation instability, the most unstable condition attracts lots of attention. The most unstable condition is investigated here with two kinds of initial wave systems via a numerical high-order spectral method (HOS) for surface water wave field. Classically, one carrier wave and a pair of sidebands are implied as the first kind of initial wave system: “seeded” wave system. In the second kind of initial wave system: “un-seeded” wave system, only one carrier wave is implied. Two impressive new results are present. One result shows that the grow rates of lower and upper sideband are different within the “seeded” wave system. It means that, for a given wave steepness, the most unstable lower sideband is not in pair with the most unstable upper sideband. Another result shows the fastest growing sidebands are exactly in pair from “unseeded” wave system. And the most unstable conditions of “unseeded” wave system are more or less the mean value of those derived from the lower sidebands and upper sidebands within the “seeded” wave system.
- Published
- 2012
30. THE OCCURRENCE PROBABILITIES OF ROGUE WAVES IN DIFFERENT NONLINEAR STAGES
- Author
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Aifeng Tao, Keren Qi, Yu-Qing Wu, Jinhai Zheng, and Ji Peng
- Subjects
business.industry ,Numerical analysis ,Instability ,Nonlinear system ,Optics ,Kurtosis ,General Earth and Planetary Sciences ,Entropy (information theory) ,Statistical physics ,Rogue wave ,business ,Spectral method ,Boltzmann's entropy formula ,General Environmental Science ,Mathematics - Abstract
The occurrence probabilities of Rogue Waves in different nonlinear states are investigated based on high-order spectral method (HOSM), which is a direct phase-resolved numerical method. The focus is given to the occurrence probability of Rogue Waves in the nonlinear evolution stage where the Benjamin-Feir Instability is not the dominate mechanism due to the quartet resonance interactions for wave fields with a broad range in frequencies. The initial wave trains are generated from Stokes waves and two sidebands. Based on the simulation, we find that the Kurtosis evolves distinctly at three nonlinear stages and shows a weak relation to the probabilities of the Rouge Waves. We also introduce a simple Entropy formula, turning out to close a stable value.
- Published
- 2014
31. EXPERIMENTAL STUDY ON CRITICAL RESONANT STATE OF UPSTREAM-ADVANCED WAVES
- Author
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Li Shuo, Jinhai Zheng, Aifeng Tao, Peng Gao, and Jun Fan
- Subjects
Physics ,Wave propagation ,business.industry ,Atmospheric wave ,Mechanics ,Internal wave ,Love wave ,symbols.namesake ,Optics ,symbols ,General Earth and Planetary Sciences ,Gravity wave ,Rayleigh wave ,Mechanical wave ,business ,Longitudinal wave ,General Environmental Science - Abstract
It is known that the upstream-advancing waves can be excited when a steady current travelling over a wavy bottom. While the generation mechanisms are still inconclusive and the related dynamic and kinematic characteristics of the excited water waves are not clear. Focusing on the dynamics of this kind of upstream-advancing waves, especially the critical generation conditions, a series of experiments were carried out in a wave-current-wind flume (80m*1.0m*1.5m) with fixed sinusoidal bottom corrugations. By varying the current velocity and relative water depth, altogether 137 cases were realized. It is found that there exist a region of the current velocity for the exciting of upstream-advancing waves, based on the whole processes recorded, from the pure current to the present of clear upstream-advancing waves to the disappear of the evident waves again. The most unstable conditions correspond to the largest wave amplitudes were investigated in details. The dynamics of the excited waves were analyzed primarily for understanding of the generation mechanisms.
- Published
- 2014
32. PROPERTIES OF FREAK WAVES INDUCED BY TWO KINDS OF NONLINEAR MECHANISMS
- Author
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Ji Peng, Aifeng Tao, Jinhai Zheng, Botao Chen, and Hui Li
- Subjects
Physics ,Nonlinear system ,Wave propagation ,Acoustics ,Modulation (music) ,General Earth and Planetary Sciences ,Stokes wave ,Mechanics ,Rogue wave ,Mechanical wave ,Instability ,Longitudinal wave ,General Environmental Science - Abstract
We investigate the dynamic and kinematic characteristics of freak waves using a direct phase-resolved nonlinear numerical method. The focus is on the understanding of the effects of different nonlinear wave-wave interactions on freak waves development and characteristics in the evolution process of modulated Stokes wave trains. Long time simulations of modulated Stokes wave trains, with different parameters, are obtained. Based on these simulations, we find that there are different kinds of freak waves in different time scales due to two kinds of different nonlinear mechanisms. One is the modulation instability and another related to the wave group interaction. Both the dynamic and kinematic characteristics of the different kinds of freak waves are distinct. Occurrence of freak waves (especially of large height) is usually correlated with broadband wave spectra.
- Published
- 2012
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