傅里叶有限差分法三维波动方程正演模拟   总被引：4，自引：6，他引：4  

张金海  王卫民  赵连锋  姚振兴 《地球物理学报》2007,50(6):1854-1862

傅里叶有限差分(FFD)法兼有相位屏法和隐式有限差分法二者的优势，能够处理复杂地质构造中的波传播问题，但在三维情形下，算子的双向分裂会引起明显的方位各向异性误差.本文用Fourier变换计算双向分裂过程中的高阶交叉项，消除了方位各向异性误差.该方法充分利用了FFD法在双域实现的算法结构，明显减少了由于引入误差校正所带来的计算量.将该方法应用于修改后的三维French模型的地震正演问题，并将得到的叠后记录、单炮记录同全波有限差分法的模拟结果进行对比，结果证实了该方法对一次反射波具有较高的模拟精度，在内存需求和计算效率方面则具有更大的优势.  相似文献   

基于Qt的VSP波场分离系统的设计与实现     

余本善  王彦春  张良庆  刘少峰  熊杰  李博 《物探与化探》2012,36(3):485-489

VSP技术是近几年发展比较迅速的一种重要地震观测方法,如何有效地分离上、下行波,是应用VSP资料所要解决的首要问题。介绍了几种常用的VSP波场分离方法原理及其实现步骤,利用跨平台的C＋＋图形用户界面库Qt,开发了VSP波场分离系统。系统操作界面友好、功能强大,已在实际资料处理中得到很好的应用。  相似文献   

Demarcation of inland vessels’ limit off Mormugao port region,India: a pilot study for the safety of inland vessels using wave modelling     

P. Vethamony  V. M. Aboobacker  K. Sudheesh  M. T. Babu  K. Ashok Kumar 《Natural Hazards》2009,49(2):411-420

The Ministry of Shipping desires to revise the inland vessels’ limit (IVL) notification based on scientific rationale to improve the safety of vessels and onboard personnel. The Mormugao port region extending up to the Panaji was considered for this pilot study. Measured winds and wave parameters (AWS and moored buoy) as well as NCEP re-analysis and NCMRWF winds were used for the analysis and input to regional and local models. The results of wave model were validated with measured significant wave heights (SWHs) and the comparison shows a good match. The analysis indicates that SWHs do not exceed 2.0 m during non-monsoon months, and in monsoon months exceed 5.0 m, and even 7.0 m, especially during extreme events. In order to draw IVL contours for Goa coastal region, local model was set up and nearshore waves were simulated for the period May 2004–May 2005. Based on the nearshore SWH distribution, IVL contours have been fixed for the Mormugao port and Panaji coastal regions.  相似文献   

Experimental and numerical investigations on zigzag porous screen breakwater     

J. S. Mani 《Natural Hazards》2009,49(2):401-409

Pile supported porous breakwaters are commonly adopted for shielding small-scale harbors, such as marinas, fishing harbors, and recreational harbors from external waves. To improve efficiency of such breakwaters, attempts have been made to provide a filter screen containing porous material. Possible alternative to the existing pile supported screen breakwaters is the zigzag breakwater. This article details on the numerical and experimental investigations carried out on the performance of zigzag porous screen breakwater. Results related to the wave amplification in front of the structure, wave reflection, and transmission, forces exerted by the waves on the structure are discussed. The studies clearly indicate that the transmission coefficient of the order of 0.5 can be achieved for H _i/gT ² > 0.008 for 50% submergence, whereas the reflection coefficient can be effectively reduced to 0.2. Reduction in wave force is of the order of 50% which is primarily due to reduction in reflection coefficient. Substantial reduction in wave force contributes directly to reduction in the cost of construction of the breakwater, a definite advantage over other similar breakwaters.  相似文献   

Effect of varied atmospheric stability on sea surface drag in shallow seas and its impact on wind-wave growth     

R. Rajesh Kumar  B. Prasad Kumar  A. N. V. Satyanarayana  D. Bala Subrahamanyam  A. D. Rao  S. K. Dube 《Natural Hazards》2009,49(2):213-224

This work reports an efficient bulk formulation of sea surface drag that incorporates effect of dynamic stability under varied atmospheric forcing. The proposed formulation exhibits a polynomial dependence of wind speed on air–sea temperature difference based on statistical analysis. Quality checked meteorological and oceanographic data from four shallow water buoys located off Korean seas having measurements at an interval of every 1 h were used for this study. The analyses of in situ records for this region suggest stability ranging from highly stable to very unstable conditions. Importance of this proposed formulation is better reflected during unstable condition where other popular bulk formulations fail. In addition, importance and impact of such a study on wind-wave growth using the state-of-art wave model was also investigated. Finally, we advocate a new drag formulation, which accounts for varied atmospheric stability and suggest that this should be considered as an essential pre-requisite for ocean modeling studies.  相似文献   

基于控制照明的合成震源记录交互剩余偏移速度分析   总被引：10，自引：0，他引：10       下载免费PDF全文

王昌龙  张叔伦  赵景霞  杨其强 《地球物理学报》2007,50(3):860-867

提出了一种新的偏移速度分析方法——基于控制照明的合成震源记录交互剩余偏移速度分析方法．与其他类似偏移速度分析方法的不同点在于：（1） 叠前深度偏移采用基于波动理论的快速合成震源记录算法；（2）偏移方法采用平面波震源，与速度分析方法一致；（3）应用控制照明技术，避免了因横向变速而导致的平面波震源波场在传播过程中的畸变，从而减小了速度分析的误差；（4）实用的速度谱设计，使交互偏移速度分析可行且易于操作．模型和新疆实际资料的试算表明该方法是一种有效和实用的偏移速度分析方法．  相似文献   

Benchmark computations of wave run-up on single cylinder and four cylinders by naoe-FOAM-SJTU solver     

《Applied Ocean Research》2017

The benchmark simulations of wave run-up on a fixed single truncated circular cylinder and four circular cylinders are presented in this paper. Our in-house CFD solver naoe-FOAM-SJTU is adopted which is an unsteady two-phase CFD code based on the open source package OpenFOAM. The Navier-Stokes equations are employed as the governing equations, and the volume of fluid (VOF) method is applied for capturing the free surface. Monochromatic incident waves with the specified wave period and wave height are simulated and wave run-up heights around the cylinder are computed and recorded with numerical virtual wave probes. The relationship between the wave run-up heights and the incident wave parameters are analyzed. The numerical results indicate that the presented naoe-FOAM-SJTU solver can provide accurate predictions for the wave run-up on one fixed cylinder and four cylinders, which has been proved by the comparison of simulated results with experimental data.  相似文献   

Stochastic analysis of the second-order hydrodynamic quantities for offshore structures     

《Applied Ocean Research》2017

The present study considers the prediction of extreme values of the second-order hydrodynamic parameters related to offshore structures in waves, where the application of Gaussian distribution is not valid. Particularly, this study focuses on a characteristic function approach in the frequency domain to estimate the probability distribution of the second-order quantities, and the results are compared with direct simulations in the time domain. The stochastic behaviors of the second-order hydrodynamic quantities are investigated with the characteristic function approach, which involves eigenvalue analyses of Hermitian kernels constructed with quadratic transfer functions. Three different second-order responses are considered: the springing responses of TLP tendons representative of the sum-frequency problem, the slow-drift motions of a semi-submersible platform moored in waves as a representative of the difference-frequency problem, and the wave run-up around a vertical column for regular and irregular waves. The applicability of the present approach in predicting extreme values is assessed by comparing the results with the values obtained from time-domain signals.  相似文献   

Numerical investigation of tsunami-like wave hydrodynamic characteristics and its comparison with solitary wave     

《Applied Ocean Research》2017

Solitary waves have been commonly used as an initial condition in the experimental and numerical modelling of tsunamis for decades. However, the main component of a tsunami waves acts at completely different spatial and temporal scales than solitary waves. Thus, use of solitary waves as approximation of a tsunami wave may not yield realistic model results, especially in the coastal region where the shoaling effect restrains the development of the tsunami wave. Alternatively, N-shaped waves may be used to give a more realistic approximation of the tsunami wave profile. Based on the superposition of the sech²(*) waves, the observed tsunami wave profile could be approximated with the N-shaped wave method, and this paper presents numerical simulation results based on the tsunami-like wave generated based on the observed tsunami wave profile measured in the Tohoku tsunami. This tsunami-like wave was numerically generated with an internal wave source method based on the two-phase incompressible flow model with a Volume of Fluid (VOF) method to capture the free surface, and a finite volume scheme was used to solve all the governing equations. The model is first validated for the case of a solitary wave propagating within a straight channel, by comparing its analytical solutions to model results. Further, model comparisons between the solitary and tsunami-like wave are then made for (a) the simulation of wave run-up on shore and (b) wave transport over breakwater. Comparisons show that use of these largely different waveform shapes as inputs produces significant differences in overall wave evolution, hydrodynamic load characteristics as well as velocity and vortex fields. Further, it was found that the solitary wave uses underestimated the total energy and hence underestimated the run-up distance.  相似文献   

Wave runup on a surging vertical cylinder in regular waves     

《Applied Ocean Research》2017

The wave runup caused by a vertical cylinder surging in regular waves is studied both experimentally and numerically. The so-called DualSPHysics Smoothed Particle Hydrodynamics (SPH) code is used for the 3-D numerical modelling. A wide range of cylinder sizes and wave conditions is investigated with results comparing favourably between the experimental and SPH model under both fixed and forced-surge conditions. The experimental and SPH results are further used to predict the maximum runup amplification, in particular the ratio of the runup caused by the surging cylinder to that of the fixed, over the phase difference between the incident wave and surge motion. This maximum runup ratio has been analysed for its dependence on factors such as wave steepness, wave scattering and surge amplitude. An empirical equation is proposed for predicting the maximum runup ratio from known incident wave and surge conditions. Comparison with results from linear solvers suggests that the linear solvers under-predict the full nonlinear runup by a factor of 1.3–1.5.  相似文献