The 2025 M_(w)7.7 Myanmar earthquake highlighted the challenge of near-fault seismic intensity field reconstruction due to sparse seismic networks.To address this limitation,a framework was proposed integrating seismi...The 2025 M_(w)7.7 Myanmar earthquake highlighted the challenge of near-fault seismic intensity field reconstruction due to sparse seismic networks.To address this limitation,a framework was proposed integrating seismic wave simulation with a data-constrained finite-fault rupture model.The constraint is implemented by identifying the optimal ground motion models(GMMs)through a scoring system that selects the best-fit GMMs to mid-and far-field China Earthquake Networks Center(CENC)seismic network data;and applying the optimal GMMs to refine the rupture model parameters for near-fault intensity field simulation.The simulated near-fault seismic intensity field reproduces seismic intensities collected from Myanmar’s sparse seismic network and concentrated in≥Ⅷintensity zones within 50 km of the projected fault plane;and identifies abnormal intensity regions exhibiting≥Ⅹintensity along the Meiktila-Naypyidaw corridor and near Shwebo that are attributed to soft soil amplification effects and near-fault directivity.This framework can also be applied to post-earthquake assessments in other similar regions.展开更多
Multi-layer riveted structures are widely applied to aircraft.During the service,cracks may appear within these structures due to stress concentration of the riveted holes.The guided wave monitoring has been proved to...Multi-layer riveted structures are widely applied to aircraft.During the service,cracks may appear within these structures due to stress concentration of the riveted holes.The guided wave monitoring has been proved to be an effective tool to deal with this problem.However,there is a lack of understanding of the wave propagation process across such kinds of structures.This study proposes a piezoelectric guided wave simulation method to reveal the propagation of guided waves in multi-layer riveted structures.Effects of pretension force,friction coefficient,and cracks that might influence wave characteristics are studied.The guided wave simulation data is compared with the experimental results and the results verify the simulation model.Then the guided wave propagation in a more complex long-beam butt joint structure is further simulated.展开更多
To deal with the numerical dispersion problem, by combining the staggeredgrid technology with the compact finite difference scheme, we derive a compact staggered- grid finite difference scheme from the first-order vel...To deal with the numerical dispersion problem, by combining the staggeredgrid technology with the compact finite difference scheme, we derive a compact staggered- grid finite difference scheme from the first-order velocity-stress wave equations for the transversely isotropic media. Comparing the principal truncation error terms of the compact staggered-grid finite difference scheme, the staggered-grid finite difference scheme, and the compact finite difference scheme, we analyze the approximation accuracy of these three schemes using Fourier analysis. Finally, seismic wave numerical simulation in transversely isotropic （VTI） media is performed using the three schemes. The results indicate that the compact staggered-grid finite difference scheme has the smallest truncation error, the highest accuracy, and the weakest numerical dispersion among the three schemes. In summary, the numerical modeling shows the validity of the compact staggered-grid finite difference scheme.展开更多
Transmitted ultrasonic wave simulation （TUWS） in a digital core is one of the important elements of digital rock physics and is used to study wave propagation in porous cores and calculate equivalent velocity. When ...Transmitted ultrasonic wave simulation （TUWS） in a digital core is one of the important elements of digital rock physics and is used to study wave propagation in porous cores and calculate equivalent velocity. When simulating wave propagates in a 3D digital core, two additional layers are attached to its two surfaces vertical to the wave-direction and one planar wave source and two receiver-arrays are properly installed. After source excitation, the two receivers then record incident and transmitted waves of the digital rock. Wave propagating velocity, which is the velocity of the digital core, is computed by the picked peak-time difference between the two recorded waves. To evaluate the accuracy of TUWS, a digital core is fully saturated with gas, oil, and water to calculate the corresponding velocities. The velocities increase with decreasing wave frequencies in the simulation frequency band, and this is considered to be the result of scattering. When the pore fluids are varied from gas to oil and finally to water, the velocity-variation characteristics between the different frequencies are similar, thereby approximately following the variation law of velocities obtained from linear elastic statics simulation （LESS）, although their absolute values are different. However, LESS has been widely used. The results of this paper show that the transmission ultrasonic simulation has high relative precision.展开更多
When simulating seismic wave propagation in free space, it is essential to introduce absorbing boundary conditions to eliminate reflections from artificially trtmcated boundaries. In this paper, a damping factor refer...When simulating seismic wave propagation in free space, it is essential to introduce absorbing boundary conditions to eliminate reflections from artificially trtmcated boundaries. In this paper, a damping factor referred to as the Gaussian dmping factor is proposed. The Gaussian damping factor is based on the idea of perfectly matched layers （PMLs）. This work presents a detailed analysis of the theoretical foundations and advantages of the Gaussian damping factor. Additionally, numerical experiments for the simulation of seismic waves are presented based on two numerical models： a homogeneous model and a multi-layer model. The results show that the proposed factor works better. The Gaussian damping factor achieves a higher Signal-to-Noise Ratio （SNR） than previously used factors when using same number of PMLs, and requires less PMLs than other methods to achieve an identical SNR.展开更多
The joint probability distribution of wind speed and significant wave height in the Bohai Bay was investigated by comparing the Gurnbel logistic model, the Gumbel-Hougaard （GH） copula function, and the Clayton copul...The joint probability distribution of wind speed and significant wave height in the Bohai Bay was investigated by comparing the Gurnbel logistic model, the Gumbel-Hougaard （GH） copula function, and the Clayton copula function. Twenty years of wind data from 1989 to 2008 were collected from the European Centre for Medium-Range Weather Forecasts （ECMWF） database and the blended wind data of the Quick Scatterometer （QSCAT） satellite data set and re-analysis data from the United States National Centers for Environmental Prediction （NCEP）. Several typhoons were taken into account and merged with the background wind fields from the ECMWF or QSCAT/NCEP database. The 20-year data of significant wave height were calculated with the unstructured-grid version of the third-generation wind wave model Simulating WAves Nearshore （SWAN） under extreme wind process conditions. The Gumbel distribution was used for univariate and marginal distributions. The distribution parameters were estimated with the method of L-moments. Based on the marginal distributions, the joint probability distributions, the associated return periods, and the conditional probability distributions were obtained. The GH copula function was found to be optimal according to the ordinary least squares （OLS） test. The results show that wind waves are the prevailing type of wave in the Bohai Bay.展开更多
A wave flume simulator was used to study internal nitrogen release from the surface sediment collected from Taihu Lake, China. Particulate nitrogen concentrations were positively correlated with the concentrations of ...A wave flume simulator was used to study internal nitrogen release from the surface sediment collected from Taihu Lake, China. Particulate nitrogen concentrations were positively correlated with the concentrations of suspended solids, primarily from surface erosion related to the shear stress and duration of wave action. In response to 4 cm- and 10 cm-high wave production representing waves generated in Taihu Lake by gentle and gusty winds, respectively, the mean dynamic release rate of ammonium （NH4＋） from the sediment to the overlying water was 1 × 10-3 mg/（m2.s） and the NH4＋ concentration in the overlying water increased by 0.016 mg/L, indicating that waves resulting from strong wind can induce the rapid release of dissolved nitrogen from Taihu Lake sediments. The decrease in interstitial NH4＋ concentrations at all sediment depths was associated with an increase in NH4＋ concentrations in the overlying water by 0.01 mg/L, showing that sediment below the eroded layer was the main source of internal nitrogen release. Changes in the interstitial dissolved oxygen and NH4＋ concentrations showed that wave-induced pore water movement can greatly increase the diffusion rate, and that these 15 cm. Diffusion induced by pore water movement sediment layer in Taihu Lake. effects can influence the sediment to a depth of at least may be very important for the formation of an active展开更多
The growth of frequency spectra and spectral parameters of wind waves generated by cold waves, a kind of severe weather system, in the northern East China Sea is studied in this paper. Based on a third-generation wave...The growth of frequency spectra and spectral parameters of wind waves generated by cold waves, a kind of severe weather system, in the northern East China Sea is studied in this paper. Based on a third-generation wave action model(the Simulating WAves Nearshore model), simulations were developed to analyze the spatiotemporal characteristics of wind waves and to output spectral data. It is shown that the cold wave-induced spectra can be well described by the modified Joint North Sea Wave Project spectral form. The growth of wave spectra is comprehensively reflected by the evolution of the three characteristic parameters: peak frequency, spectral peak and wave energy. Besides, the approximations of dependences between spectral parameters and the three types of universal induced factors are obtained with the least squares method and compared systematically. Fetch and peak frequency turn out to be suitable parameters to describe the spectral parameters, while the dependences on the inverse wave age vary in different sea areas. In general, the derived relationships improve on results from previous studies for better practical application of the wind wave frequency spectrum in the northern East China Sea.展开更多
Numerical wave tanks are widely-acknowledged tools in studying waves and wave-structure interactions. They can generate waves under realistic scales and offers more information on the fluid field. However, most numeri...Numerical wave tanks are widely-acknowledged tools in studying waves and wave-structure interactions. They can generate waves under realistic scales and offers more information on the fluid field. However, most numerical wave tanks suffer from issues known as the numerical dissipation and numerical dispersion. The former causes wave energy to be slowly dissipated and the latter shifts wave frequencies during wave propagation. This paper proposes a simple method of depressing numerical dissipation effects on the basis of solving Euler equations using the finite difference method(FDM). The wave propagation solutions are solved analytically taking into account the influence of the damping terms. The main idea of the method is to append a source term to the momentum equation, whose strength is determined by how strong the numerical damping effect is. The method is verified by successfully depressing numerical effects during the simulation of regular linear waves, Stokes waves and irregular waves. By applying the method, wave energy is able to be close to its initial value after long distance of travel.展开更多
The size and shape of the effective test area are crucial to consider when short-crested waves are created by segmented wavemakers. The range of the effective test area of short-crested waves simulated by two-sided se...The size and shape of the effective test area are crucial to consider when short-crested waves are created by segmented wavemakers. The range of the effective test area of short-crested waves simulated by two-sided segmented wavemakers is analyzed in this paper. The experimental investigation on the wave field distribution of short-crested waves generated by two-sided segmented wavemakers is conducted by using an array of wave gauges. Wave spectra and directional spreading function are analyzed and the results show that when the main direction is at a certain angle with the normal line of wave generators, the wave field of 3D short-crested waves generated by two-sided segmented wavemakers has good spatial uniformity within the model test area. The effective test area can provide good wave environments for seakeeping model tests of various ocean engineering structures in the deep ocean engineering basin.展开更多
Record-breaking high waves occurred during the passage of the typhoon Bolaven（1215）（TYB） in the East China Sea（ECS） and Yellow Sea（YS） although its intensity did not reach the level of a super typhoon.Winds an...Record-breaking high waves occurred during the passage of the typhoon Bolaven（1215）（TYB） in the East China Sea（ECS） and Yellow Sea（YS） although its intensity did not reach the level of a super typhoon.Winds and directional wave measurements were made using a range of in-situ instruments mounted on an ocean tower and buoys.In order to understand how such high waves with long duration occurred,analyses have been made through measurement and numerical simulations.TYB winds were generated using the TC96 typhoon wind model with the best track data calibrated with the measurements.And then the wind fields were blended with the reanalyzed synoptic-scale wind fields for a wave model.Wave fields were simulated using WAM4.5 with adjustment of C_d for gust of winds and bottom friction for the study area.Thus the accuracy of simulations is considerably enhanced,and the computed results are also in better agreement with measured data than before.It is found that the extremely high waves evolved as a result of the superposition of distant large swells and high wind seas generated by strong winds from the front/right quadrant of the typhoon track.As the typhoon moved at a speed a little slower than the dominant wave group velocity in a consistent direction for two days,the wave growth was significantly enhanced by strong wind input in an extended fetch and non-linear interaction.展开更多
To study on the numerical simulation calculation reliability of sea-crossing bridge under complex wave forces,the paper applied GPS deformation monitoring and numerical simulation calculation by researching Qingdao Ji...To study on the numerical simulation calculation reliability of sea-crossing bridge under complex wave forces,the paper applied GPS deformation monitoring and numerical simulation calculation by researching Qingdao Jiaozhou Bay Sea-Crossing Bridge.The db3 wavelet three-layer decomposition was used on the horizontal movement of the sea-crossing bridge and the wind speed of the waves to analyze their correlation.The complex wave forces value of Qingdao Jiaozhou Bay Sea-Crossing Bridge was loaded on FLAC3D software successfully to make numerical simulation calculation of bridge deformation.Since the accuracy of the GPS deformation monitoring reaches millimeter level,it was used to monitor the exact value of the bridge deformation to judge the reliability of numerical simulation.The relative errors of displacement in X,Y and Z directions were between 33%and 41%through comparison.It could be seen that the numerical simulation error was relatively large,which was mainly due to various environmental factors and the deviation of applied wave forces.However,numerical simulation generally reflects the deformation law of the sea-crossing bridge under complex wave forces,providing an effectively technical support for the safe operation assessment of the sea-crossing bridge.展开更多
This paper extends a prediction model for multi-directional random wave transformation based on an energy balance equation by Mase with the consideration of wave shoaling, refraction, diffraction, reflection and break...This paper extends a prediction model for multi-directional random wave transformation based on an energy balance equation by Mase with the consideration of wave shoaling, refraction, diffraction, reflection and breaking. This numerical model is improved by 1) introducing Wen's frequency spectrum and Mitsuyasu's directional function, which are more suitable to the coastal area of China; 2) considering energy dissipation caused by bottom friction, which ensures more accurate results for large-scale and shallow water areas; 3) taking into account a non-linear dispersion relation. Predictions using the extended wave model are carried out to study the feasibility of constructing the Ai Hua yacht port in Qingdao, China, with a comparison between two port layouts in design. Wave fields inside the port for different incident wave directions, water levels and return periods are simulated, and then two kinds of parameters are calculated to evaluate the wave conditions for the two layouts. Analyses show that Layout I is better than Layout II. Calculation results also show that the harbor will be calm for different wave directions under the design water level. On the contrary, the wave conditions do not wholly meet the requirements of a yacht port for ship berthing under the extreme water level. For safety consideration, the elevation of the breakwater might need to be properly increased to prevent wave overtopping under such water level. The extended numerical simulation model may provide an effective approach to computing wave heights in a harbor.展开更多
The characteristic of combustion wave and its change were analyzed by numerical value calculation and computer simulation, based on the combustion dynamical model of SHS process. It is shown that with the change of co...The characteristic of combustion wave and its change were analyzed by numerical value calculation and computer simulation, based on the combustion dynamical model of SHS process. It is shown that with the change of condition parameters in SHS process various time-space order combustion waves appear. It is concluded from non-liner dynamical mechanism analysis that the strong coupling of two non-linear dynamical processes is the dynamical mechanism causing the time-space order dissipation structures.展开更多
Seismic wave propagation in fluid-solid coupled media is currently a popular topic. However, traditional wave equation-based simulation methods have to consider complex boundary conditions at the fluid-solid interface...Seismic wave propagation in fluid-solid coupled media is currently a popular topic. However, traditional wave equation-based simulation methods have to consider complex boundary conditions at the fluid-solid interface. To address this challenge, we propose a novel numerical scheme that integrates the lattice Boltzmann method(LBM) and lattice spring model(LSM). In this scheme, LBM simulates viscoacoustic wave propagation in the fluid area and LSM simulates elastic wave propagation in the solid area. We also introduce three different LBM-LSM coupling strategies, a standard bounce back scheme, a specular reflection scheme, and a hybrid scheme, to describe wave propagation across fluid-solid boundaries. To demonstrate the accuracy of these LBM-LSM coupling schemes, we simulate wave propagation in a two-layer model containing a fluid-solid interface. We place excitation sources in the fluid layer and the solid layer respectively, to observe the wave phenomena when seismic waves propagate to interface from different sides. The simulated results by LBM-LSM are compared with the reference wavefields obtained by the finite difference method(FDM) and the analytical solution(ANA).Our LBM-LSM coupling scheme was verified effective, as the relative errors between the LBM-LSM solutions and reference solutions were within an acceptable range, sometimes around 1.00%. The coupled LBM-LSM scheme is further used to model seismic wavefields across a more realistic rugged seabed,which reveals the potential applications of the coupled LBM-LSM scheme in marine seismic imaging techniques, such as reverse-time migration and full-waveform inversion. The method also has potential applications in simulating wave propagation in complex two-and multi-phase media.展开更多
In 3D frequency domain seismic forward and inversion calculation,the huge amount of calculation and storage is one of the main factors that restrict the processing speed and calculation efficiency.The frequency domain...In 3D frequency domain seismic forward and inversion calculation,the huge amount of calculation and storage is one of the main factors that restrict the processing speed and calculation efficiency.The frequency domain finite-difference forward simulation algorithm based on the acoustic wave equation establishes a large bandwidth complex matrix according to the discretized acoustic wave equation,and then the frequency domain wave field value is obtained by solving the matrix equation.In this study,the predecessor's optimized five-point method is extended to a 3D seven-point finite-difference scheme,and then a perfectly matched layer absorbing boundary condition(PML)is added to establish the corresponding matrix equation.In order to solve the complex matrix,we transform it to the equivalent real number domain to expand the solvable range of the matrix,and establish two objective functions to transform the matrix solving problem into an optimization problem that can be solved using gradient methods,and then use conjugate gradient algorithm to solve the problem.Previous studies have shown that in the conjugate gradient algorithm,the product of the matrix and the vector is the main factor that affects the calculation efficiency.Therefore,this study proposes a method that transform bandwidth matrix and vector product problem into some equivalent vector and vector product algorithm,thereby reducing the amount of calculation and storage.展开更多
In this paper,we consider the numerical implementation of the 2D wave equation in isotropic-heterogeneous media.The stability analysis of the scheme using the von Neumann stability method has been studied.We conducted...In this paper,we consider the numerical implementation of the 2D wave equation in isotropic-heterogeneous media.The stability analysis of the scheme using the von Neumann stability method has been studied.We conducted a study on modeling the propagation of acoustic waves in a heterogeneous medium and performed numerical simulations in various heterogeneous media at different time steps.Developed parallel code using Compute Unified Device Architecture(CUDA)technology and tested on domains of various sizes.Performance analysis showed that our parallel approach showed significant speedup compared to sequential code on the Central Processing Unit(CPU).The proposed parallel visualization simulator can be an important tool for numerous wave control systems in engineering practice.展开更多
Smoothed Particle Hydrodynamics (SPH) is a Lagrangian meshless particle method. However, its low accuracy of kernel approximation when particles are distributed disorderly or located near the boundary is an obstacle s...Smoothed Particle Hydrodynamics (SPH) is a Lagrangian meshless particle method. However, its low accuracy of kernel approximation when particles are distributed disorderly or located near the boundary is an obstacle standing in the way of its wide application. Adopting the Taylor series expansion method and solving the integral equation matrix, the second order kernel approximation method can be obtained, namely K2_SPH, which is discussed in this paper. This method is similar to the Finite Particle Method. With the improvement of kernel approximation, some numerical techniques should be adopted for different types of boundaries, such as a free surface boundary and solid boundary, which are two key numerical techniques of K2_SPH for water wave simulation. This paper gives some numerical results of two dimensional water wave simulations involving standing wave and sloshing tank problems by using K2_SPH. From the comparison of simulation results, the K2_SPH method is more reliable than standard SPH.展开更多
The complexity of near surface intensifies the diversity of seismic wave fields, which makes study on near surface wavefields important in many aspects. The strong absorption of low velocity layer can affect the resol...The complexity of near surface intensifies the diversity of seismic wave fields, which makes study on near surface wavefields important in many aspects. The strong absorption of low velocity layer can affect the resolution of seismic data, and free boundary can cause surface wave. Considering the above problems, we focus on the Rayleigh wavefields simulation using finite-difference wave equation of higher-order staggered grids and PML boundary conditions. Free boundary, buried source and overlying low velocity layer are taken into consideration and point explosion source is adopted. Through some numerical simulation with different parameters, we quantitatively analyze relationship between wave intensity and source depth, as well as the energy variation with propagation and obtain some practical knowledge and conclusions.展开更多
The shock wave acceleration of ions driven by laser-heated thermal pressure is studied through one-dimensional particle-in-cell simulation and analysis. The generation of high-energy mono-energetic protons in recent e...The shock wave acceleration of ions driven by laser-heated thermal pressure is studied through one-dimensional particle-in-cell simulation and analysis. The generation of high-energy mono-energetic protons in recent experiments （D. Haberberger et al., 2012 Nat. Phys. 8 95） is attributed to the use of exponentially decaying density profile of the plasma target. It does not only keep the shock velocity stable but also suppresses the normal target normal sheath acceleration. The effects of target composition are also examined, where a similar collective velocity of all ion species is demonstrated. The results also give some reference to future experiments of producing energetic heavy ions.展开更多
基金Scientific Research Fund of Institute of Engineering Mechanics,China Earthquake Administration under Grant No.2023C01National Natural Science Foundation of China under Grant No.52478570Distinguished Young Scholars Program of the Natural Science Foundation of Heilongjiang Province,China under Grant No.JQ2024E002。
文摘The 2025 M_(w)7.7 Myanmar earthquake highlighted the challenge of near-fault seismic intensity field reconstruction due to sparse seismic networks.To address this limitation,a framework was proposed integrating seismic wave simulation with a data-constrained finite-fault rupture model.The constraint is implemented by identifying the optimal ground motion models(GMMs)through a scoring system that selects the best-fit GMMs to mid-and far-field China Earthquake Networks Center(CENC)seismic network data;and applying the optimal GMMs to refine the rupture model parameters for near-fault intensity field simulation.The simulated near-fault seismic intensity field reproduces seismic intensities collected from Myanmar’s sparse seismic network and concentrated in≥Ⅷintensity zones within 50 km of the projected fault plane;and identifies abnormal intensity regions exhibiting≥Ⅹintensity along the Meiktila-Naypyidaw corridor and near Shwebo that are attributed to soft soil amplification effects and near-fault directivity.This framework can also be applied to post-earthquake assessments in other similar regions.
文摘Multi-layer riveted structures are widely applied to aircraft.During the service,cracks may appear within these structures due to stress concentration of the riveted holes.The guided wave monitoring has been proved to be an effective tool to deal with this problem.However,there is a lack of understanding of the wave propagation process across such kinds of structures.This study proposes a piezoelectric guided wave simulation method to reveal the propagation of guided waves in multi-layer riveted structures.Effects of pretension force,friction coefficient,and cracks that might influence wave characteristics are studied.The guided wave simulation data is compared with the experimental results and the results verify the simulation model.Then the guided wave propagation in a more complex long-beam butt joint structure is further simulated.
基金supported by the National High-Tech Research and Development Program of China(Grant No.2006AA06Z202)the Open Fund of the Key Laboratory of Geophysical Exploration of CNPC(Grant No.GPKL0802)+1 种基金the Graduate Student Innovation Fund of China University of Petroleum(East China)(Grant No.S2008-1)the Program for New Century Excellent Talents in University(Grant No.NCET-07-0845)
文摘To deal with the numerical dispersion problem, by combining the staggeredgrid technology with the compact finite difference scheme, we derive a compact staggered- grid finite difference scheme from the first-order velocity-stress wave equations for the transversely isotropic media. Comparing the principal truncation error terms of the compact staggered-grid finite difference scheme, the staggered-grid finite difference scheme, and the compact finite difference scheme, we analyze the approximation accuracy of these three schemes using Fourier analysis. Finally, seismic wave numerical simulation in transversely isotropic （VTI） media is performed using the three schemes. The results indicate that the compact staggered-grid finite difference scheme has the smallest truncation error, the highest accuracy, and the weakest numerical dispersion among the three schemes. In summary, the numerical modeling shows the validity of the compact staggered-grid finite difference scheme.
基金supported by the Open Fund of the Key Laboratory of Exploration Technologies for Oil and Gas Resources(Yangtze University)the Ministry of Education(No.K2014-06)the Reservoir Geophysical Research Center at Yangtze University
文摘Transmitted ultrasonic wave simulation （TUWS） in a digital core is one of the important elements of digital rock physics and is used to study wave propagation in porous cores and calculate equivalent velocity. When simulating wave propagates in a 3D digital core, two additional layers are attached to its two surfaces vertical to the wave-direction and one planar wave source and two receiver-arrays are properly installed. After source excitation, the two receivers then record incident and transmitted waves of the digital rock. Wave propagating velocity, which is the velocity of the digital core, is computed by the picked peak-time difference between the two recorded waves. To evaluate the accuracy of TUWS, a digital core is fully saturated with gas, oil, and water to calculate the corresponding velocities. The velocities increase with decreasing wave frequencies in the simulation frequency band, and this is considered to be the result of scattering. When the pore fluids are varied from gas to oil and finally to water, the velocity-variation characteristics between the different frequencies are similar, thereby approximately following the variation law of velocities obtained from linear elastic statics simulation （LESS）, although their absolute values are different. However, LESS has been widely used. The results of this paper show that the transmission ultrasonic simulation has high relative precision.
基金supported by the National Natural Science Foundation of China(No. 61072118)
文摘When simulating seismic wave propagation in free space, it is essential to introduce absorbing boundary conditions to eliminate reflections from artificially trtmcated boundaries. In this paper, a damping factor referred to as the Gaussian dmping factor is proposed. The Gaussian damping factor is based on the idea of perfectly matched layers （PMLs）. This work presents a detailed analysis of the theoretical foundations and advantages of the Gaussian damping factor. Additionally, numerical experiments for the simulation of seismic waves are presented based on two numerical models： a homogeneous model and a multi-layer model. The results show that the proposed factor works better. The Gaussian damping factor achieves a higher Signal-to-Noise Ratio （SNR） than previously used factors when using same number of PMLs, and requires less PMLs than other methods to achieve an identical SNR.
基金supported by the Science Fund for Creative Research Groups of the National Natural ScienceFoundation of China (Grant No. 51021004)the National High Technology Research and DevelopmentProgram of China (863 Program, Grants No. 2012AA112509 and 2012AA051702)
文摘The joint probability distribution of wind speed and significant wave height in the Bohai Bay was investigated by comparing the Gurnbel logistic model, the Gumbel-Hougaard （GH） copula function, and the Clayton copula function. Twenty years of wind data from 1989 to 2008 were collected from the European Centre for Medium-Range Weather Forecasts （ECMWF） database and the blended wind data of the Quick Scatterometer （QSCAT） satellite data set and re-analysis data from the United States National Centers for Environmental Prediction （NCEP）. Several typhoons were taken into account and merged with the background wind fields from the ECMWF or QSCAT/NCEP database. The 20-year data of significant wave height were calculated with the unstructured-grid version of the third-generation wind wave model Simulating WAves Nearshore （SWAN） under extreme wind process conditions. The Gumbel distribution was used for univariate and marginal distributions. The distribution parameters were estimated with the method of L-moments. Based on the marginal distributions, the joint probability distributions, the associated return periods, and the conditional probability distributions were obtained. The GH copula function was found to be optimal according to the ordinary least squares （OLS） test. The results show that wind waves are the prevailing type of wave in the Bohai Bay.
基金Supported by the National Natural Science Foundation of China(Nos.41101458, 40825004,40871095,40801200)the Major Project for National Science and Technology Development(No.2010ZX03006-006)the "100-Talent Project" of Chinese Academy of Sciences,China(No.YOBROB045)
文摘A wave flume simulator was used to study internal nitrogen release from the surface sediment collected from Taihu Lake, China. Particulate nitrogen concentrations were positively correlated with the concentrations of suspended solids, primarily from surface erosion related to the shear stress and duration of wave action. In response to 4 cm- and 10 cm-high wave production representing waves generated in Taihu Lake by gentle and gusty winds, respectively, the mean dynamic release rate of ammonium （NH4＋） from the sediment to the overlying water was 1 × 10-3 mg/（m2.s） and the NH4＋ concentration in the overlying water increased by 0.016 mg/L, indicating that waves resulting from strong wind can induce the rapid release of dissolved nitrogen from Taihu Lake sediments. The decrease in interstitial NH4＋ concentrations at all sediment depths was associated with an increase in NH4＋ concentrations in the overlying water by 0.01 mg/L, showing that sediment below the eroded layer was the main source of internal nitrogen release. Changes in the interstitial dissolved oxygen and NH4＋ concentrations showed that wave-induced pore water movement can greatly increase the diffusion rate, and that these 15 cm. Diffusion induced by pore water movement sediment layer in Taihu Lake. effects can influence the sediment to a depth of at least may be very important for the formation of an active
基金Supported by the National Key Research and Development Program of China(No.2016YFC1402000)the National Natural Science Foundation of China(Nos.41376027,41406017,U1406401,41421005)
文摘The growth of frequency spectra and spectral parameters of wind waves generated by cold waves, a kind of severe weather system, in the northern East China Sea is studied in this paper. Based on a third-generation wave action model(the Simulating WAves Nearshore model), simulations were developed to analyze the spatiotemporal characteristics of wind waves and to output spectral data. It is shown that the cold wave-induced spectra can be well described by the modified Joint North Sea Wave Project spectral form. The growth of wave spectra is comprehensively reflected by the evolution of the three characteristic parameters: peak frequency, spectral peak and wave energy. Besides, the approximations of dependences between spectral parameters and the three types of universal induced factors are obtained with the least squares method and compared systematically. Fetch and peak frequency turn out to be suitable parameters to describe the spectral parameters, while the dependences on the inverse wave age vary in different sea areas. In general, the derived relationships improve on results from previous studies for better practical application of the wind wave frequency spectrum in the northern East China Sea.
基金The National Natural Science Foundation of China under contract No.51609101 and 51909103the Natural Science Foundation of Fujian Province of China under contract Nos 2017J01701,2017J05085 and 2018J05090the Outstanding Young University Scientific Research Talents Cultivation Plan of Fujian Province of China
文摘Numerical wave tanks are widely-acknowledged tools in studying waves and wave-structure interactions. They can generate waves under realistic scales and offers more information on the fluid field. However, most numerical wave tanks suffer from issues known as the numerical dissipation and numerical dispersion. The former causes wave energy to be slowly dissipated and the latter shifts wave frequencies during wave propagation. This paper proposes a simple method of depressing numerical dissipation effects on the basis of solving Euler equations using the finite difference method(FDM). The wave propagation solutions are solved analytically taking into account the influence of the damping terms. The main idea of the method is to append a source term to the momentum equation, whose strength is determined by how strong the numerical damping effect is. The method is verified by successfully depressing numerical effects during the simulation of regular linear waves, Stokes waves and irregular waves. By applying the method, wave energy is able to be close to its initial value after long distance of travel.
基金financially supported by the National Natural Science Foundation of China(Grant No.51239007)
文摘The size and shape of the effective test area are crucial to consider when short-crested waves are created by segmented wavemakers. The range of the effective test area of short-crested waves simulated by two-sided segmented wavemakers is analyzed in this paper. The experimental investigation on the wave field distribution of short-crested waves generated by two-sided segmented wavemakers is conducted by using an array of wave gauges. Wave spectra and directional spreading function are analyzed and the results show that when the main direction is at a certain angle with the normal line of wave generators, the wave field of 3D short-crested waves generated by two-sided segmented wavemakers has good spatial uniformity within the model test area. The effective test area can provide good wave environments for seakeeping model tests of various ocean engineering structures in the deep ocean engineering basin.
基金The Ministry of Oceans and Fisheries of Korea-"The Research and Development on Coastal Hydraulic Investigation of Busan New Port"and"Cooperative Project on Korea-China Bilateral Committee on Ocean Science"the Korea Institute of Ocean Science and Technology(KIOST)Project under contract No.PE99325+1 种基金the China-Korea Joint Ocean Research Center(CKJORC)-"Cooperation on the Development of Basic Technologies for the Yellow Sea and East China Sea Operational Oceanographic System(YOOS)"the Nuclear Safety Project of CKJORC and Major Project of KIOST under contract No.PE99304
文摘Record-breaking high waves occurred during the passage of the typhoon Bolaven（1215）（TYB） in the East China Sea（ECS） and Yellow Sea（YS） although its intensity did not reach the level of a super typhoon.Winds and directional wave measurements were made using a range of in-situ instruments mounted on an ocean tower and buoys.In order to understand how such high waves with long duration occurred,analyses have been made through measurement and numerical simulations.TYB winds were generated using the TC96 typhoon wind model with the best track data calibrated with the measurements.And then the wind fields were blended with the reanalyzed synoptic-scale wind fields for a wave model.Wave fields were simulated using WAM4.5 with adjustment of C_d for gust of winds and bottom friction for the study area.Thus the accuracy of simulations is considerably enhanced,and the computed results are also in better agreement with measured data than before.It is found that the extremely high waves evolved as a result of the superposition of distant large swells and high wind seas generated by strong winds from the front/right quadrant of the typhoon track.As the typhoon moved at a speed a little slower than the dominant wave group velocity in a consistent direction for two days,the wave growth was significantly enhanced by strong wind input in an extended fetch and non-linear interaction.
基金supported by the Natural Science Foundation of Shandong Province(No.ZR2020MD024)。
文摘To study on the numerical simulation calculation reliability of sea-crossing bridge under complex wave forces,the paper applied GPS deformation monitoring and numerical simulation calculation by researching Qingdao Jiaozhou Bay Sea-Crossing Bridge.The db3 wavelet three-layer decomposition was used on the horizontal movement of the sea-crossing bridge and the wind speed of the waves to analyze their correlation.The complex wave forces value of Qingdao Jiaozhou Bay Sea-Crossing Bridge was loaded on FLAC3D software successfully to make numerical simulation calculation of bridge deformation.Since the accuracy of the GPS deformation monitoring reaches millimeter level,it was used to monitor the exact value of the bridge deformation to judge the reliability of numerical simulation.The relative errors of displacement in X,Y and Z directions were between 33%and 41%through comparison.It could be seen that the numerical simulation error was relatively large,which was mainly due to various environmental factors and the deviation of applied wave forces.However,numerical simulation generally reflects the deformation law of the sea-crossing bridge under complex wave forces,providing an effectively technical support for the safe operation assessment of the sea-crossing bridge.
基金supported by the National Natural Science Foundation of China (50879085)the Program for New Century Excellent Talents in University(NCET-07-0778)Fundamental Research Funds for the Central Universities (2012QNA4020)
文摘This paper extends a prediction model for multi-directional random wave transformation based on an energy balance equation by Mase with the consideration of wave shoaling, refraction, diffraction, reflection and breaking. This numerical model is improved by 1) introducing Wen's frequency spectrum and Mitsuyasu's directional function, which are more suitable to the coastal area of China; 2) considering energy dissipation caused by bottom friction, which ensures more accurate results for large-scale and shallow water areas; 3) taking into account a non-linear dispersion relation. Predictions using the extended wave model are carried out to study the feasibility of constructing the Ai Hua yacht port in Qingdao, China, with a comparison between two port layouts in design. Wave fields inside the port for different incident wave directions, water levels and return periods are simulated, and then two kinds of parameters are calculated to evaluate the wave conditions for the two layouts. Analyses show that Layout I is better than Layout II. Calculation results also show that the harbor will be calm for different wave directions under the design water level. On the contrary, the wave conditions do not wholly meet the requirements of a yacht port for ship berthing under the extreme water level. For safety consideration, the elevation of the breakwater might need to be properly increased to prevent wave overtopping under such water level. The extended numerical simulation model may provide an effective approach to computing wave heights in a harbor.
基金Funded by the National Natural Science Foundation of Chi-na(50062001)
文摘The characteristic of combustion wave and its change were analyzed by numerical value calculation and computer simulation, based on the combustion dynamical model of SHS process. It is shown that with the change of condition parameters in SHS process various time-space order combustion waves appear. It is concluded from non-liner dynamical mechanism analysis that the strong coupling of two non-linear dynamical processes is the dynamical mechanism causing the time-space order dissipation structures.
基金supported in part by R & D Department of China National Petroleum Corporation (2022DQ0604-01)National Natural Science Foundation of China (42204132)+3 种基金the China Postdoctoral Science Foundations (2020M680667, 2021T140661)Harvard-CUP Joint Laboratory on Petroleum Science“111” project (B13010)the financial support from the CAS Special Research Assistant Project。
文摘Seismic wave propagation in fluid-solid coupled media is currently a popular topic. However, traditional wave equation-based simulation methods have to consider complex boundary conditions at the fluid-solid interface. To address this challenge, we propose a novel numerical scheme that integrates the lattice Boltzmann method(LBM) and lattice spring model(LSM). In this scheme, LBM simulates viscoacoustic wave propagation in the fluid area and LSM simulates elastic wave propagation in the solid area. We also introduce three different LBM-LSM coupling strategies, a standard bounce back scheme, a specular reflection scheme, and a hybrid scheme, to describe wave propagation across fluid-solid boundaries. To demonstrate the accuracy of these LBM-LSM coupling schemes, we simulate wave propagation in a two-layer model containing a fluid-solid interface. We place excitation sources in the fluid layer and the solid layer respectively, to observe the wave phenomena when seismic waves propagate to interface from different sides. The simulated results by LBM-LSM are compared with the reference wavefields obtained by the finite difference method(FDM) and the analytical solution(ANA).Our LBM-LSM coupling scheme was verified effective, as the relative errors between the LBM-LSM solutions and reference solutions were within an acceptable range, sometimes around 1.00%. The coupled LBM-LSM scheme is further used to model seismic wavefields across a more realistic rugged seabed,which reveals the potential applications of the coupled LBM-LSM scheme in marine seismic imaging techniques, such as reverse-time migration and full-waveform inversion. The method also has potential applications in simulating wave propagation in complex two-and multi-phase media.
基金supported by the National Natural Science Foundation of China(Project U1901602&41790465)Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(GML2019ZD0203)+2 种基金Shenzhen Key Laboratory of Deep Offshore Oil and Gas Exploration Technology(Grant No.ZDSYS20190902093007855)Shenzhen Science and Technology Program(Grant No.KQTD20170810111725321)the leading talents of Guangdong province program(Grant No.2016LJ06N652).
文摘In 3D frequency domain seismic forward and inversion calculation,the huge amount of calculation and storage is one of the main factors that restrict the processing speed and calculation efficiency.The frequency domain finite-difference forward simulation algorithm based on the acoustic wave equation establishes a large bandwidth complex matrix according to the discretized acoustic wave equation,and then the frequency domain wave field value is obtained by solving the matrix equation.In this study,the predecessor's optimized five-point method is extended to a 3D seven-point finite-difference scheme,and then a perfectly matched layer absorbing boundary condition(PML)is added to establish the corresponding matrix equation.In order to solve the complex matrix,we transform it to the equivalent real number domain to expand the solvable range of the matrix,and establish two objective functions to transform the matrix solving problem into an optimization problem that can be solved using gradient methods,and then use conjugate gradient algorithm to solve the problem.Previous studies have shown that in the conjugate gradient algorithm,the product of the matrix and the vector is the main factor that affects the calculation efficiency.Therefore,this study proposes a method that transform bandwidth matrix and vector product problem into some equivalent vector and vector product algorithm,thereby reducing the amount of calculation and storage.
基金funded by the Committee of Science of the Ministry of Science and Higher Education of the Republic of Kazakhstan(Grants No.AP14972032)NT is also supported by the Beatriu de Pinós programme and by AGAUR(Generalitat de Catalunya)grant 2021 SGR 00087.
文摘In this paper,we consider the numerical implementation of the 2D wave equation in isotropic-heterogeneous media.The stability analysis of the scheme using the von Neumann stability method has been studied.We conducted a study on modeling the propagation of acoustic waves in a heterogeneous medium and performed numerical simulations in various heterogeneous media at different time steps.Developed parallel code using Compute Unified Device Architecture(CUDA)technology and tested on domains of various sizes.Performance analysis showed that our parallel approach showed significant speedup compared to sequential code on the Central Processing Unit(CPU).The proposed parallel visualization simulator can be an important tool for numerous wave control systems in engineering practice.
基金Supported by the National Natural Science Fundation of China (51009034)Foundational Research Funds of Harbin Engineering University (HEUFT05023, HEUFP05001)+1 种基金Foundational Research Funds for the central Universities (HEUCF100102)The 111 program (B07019)
文摘Smoothed Particle Hydrodynamics (SPH) is a Lagrangian meshless particle method. However, its low accuracy of kernel approximation when particles are distributed disorderly or located near the boundary is an obstacle standing in the way of its wide application. Adopting the Taylor series expansion method and solving the integral equation matrix, the second order kernel approximation method can be obtained, namely K2_SPH, which is discussed in this paper. This method is similar to the Finite Particle Method. With the improvement of kernel approximation, some numerical techniques should be adopted for different types of boundaries, such as a free surface boundary and solid boundary, which are two key numerical techniques of K2_SPH for water wave simulation. This paper gives some numerical results of two dimensional water wave simulations involving standing wave and sloshing tank problems by using K2_SPH. From the comparison of simulation results, the K2_SPH method is more reliable than standard SPH.
基金support of the Major National Science and Technology Projects(No.2011ZX05006-002)the Fundamental Research Funds for the Central Universities of China(No.09CX04009A)
文摘The complexity of near surface intensifies the diversity of seismic wave fields, which makes study on near surface wavefields important in many aspects. The strong absorption of low velocity layer can affect the resolution of seismic data, and free boundary can cause surface wave. Considering the above problems, we focus on the Rayleigh wavefields simulation using finite-difference wave equation of higher-order staggered grids and PML boundary conditions. Free boundary, buried source and overlying low velocity layer are taken into consideration and point explosion source is adopted. Through some numerical simulation with different parameters, we quantitatively analyze relationship between wave intensity and source depth, as well as the energy variation with propagation and obtain some practical knowledge and conclusions.
基金Project supported by the Shanghai Natural Special Foundation for Outstanding Young Teachers in University,China(Grant No.yyy10043)
文摘The shock wave acceleration of ions driven by laser-heated thermal pressure is studied through one-dimensional particle-in-cell simulation and analysis. The generation of high-energy mono-energetic protons in recent experiments （D. Haberberger et al., 2012 Nat. Phys. 8 95） is attributed to the use of exponentially decaying density profile of the plasma target. It does not only keep the shock velocity stable but also suppresses the normal target normal sheath acceleration. The effects of target composition are also examined, where a similar collective velocity of all ion species is demonstrated. The results also give some reference to future experiments of producing energetic heavy ions.
