基于微增模型的海洋可控源电磁法三维非结构化矢量有限元数值模拟          下载免费PDF全文

陈汉波  李桐林  熊彬  王恒  张镕哲  李少朋 《地球物理学报》2018,61(6):2560-2577

为了分析海洋中含金属矿的储油气砂层的成分、结构对于海洋可控源电磁场的影响特征,引入多相微增等效介质模型,结合非结构化网格实现了海洋可控源电磁三维矢量有限元正演.首先对多相微增模型进行了介绍,并分析不同参数影响下的等效电导率变化特征.而后,详细推导了频率域可控源电磁法非结构化矢量有限元方程.接着,利用预处理的IDR （s）迭代算法求解线性方程组.最后设计典型的海洋地电模型,通过正演计算,验证了本文算法的正确性和有效性,同时研究了海洋储油砂层中的金属矿的含量、孔隙度、含水饱和度等参数对于可控源电磁场响应特征的影响.  相似文献   

Simulation for the propulsion of a micro-hydro robot with an unstructured grid     

M.C. Kim  H.K. Kang  H.H. Chun  H.J. Choi  H.J. Kim 《Ocean Engineering》2008,35(8-9):912-919

The flow mechanism of contractive and dilative motion was numerically investigated to obtain a propulsive force in a highly viscous fluid. The computing program for the analysis of complicated motions was numerically developed with a cell-centered, unstructured grid scheme. The developed program was validated by the well-known equation of an oscillating plane below viscous fluid for an unsteady problem, which is known as Stokes’ second problem. Validation has continued through comparison with the experimental results.In this case, sinusoidal motion was applied to the validation, instead of trochoidal motion, because it was very difficult to actually simulate trochoidal motion in this experiment. Finally, the validation and comparison with the nodal-point scheme was accomplished by Stokes’ problem, which is the famous problem at a low Reynolds number. The validated code was applied to contractive and dilative motion in a narrow tube, whose motion was embodied by trochoidal movement. In a highly viscous fluid, such as a very sticky honey or a swamp, the computed results show that a viscous force can be used for propulsion instead of a dynamic force.From the present results, it was found that a propulsive force can be obtained by contractive and dilative motion at a low Reynolds number, which can be applied to the propulsion of micro-robots in a highly viscous fluid such as a blood vessel or a swamp. This research could also be considered fundamental research for the propulsion of micro-hydro robots, which are expected to be actively studied in the future in accord with further development of nanotechnology.  相似文献   

Interactions between fully nonlinear water waves and cylinder arrays in a wave tank     

C.Z. Wang 《Ocean Engineering》2010,37(4):400-417

Fully nonlinear interactions between water waves and vertical cylinder arrays in a numerical tank are studied based on a finite element method (FEM). The three-dimensional (3D) mesh is constructed through an extension of a 2D Delaunay surface grid along the vertical line. The velocity potential is obtained by solving a linear matrix system of FEM, and a difference scheme is then used to calculate the velocity on the free surface to track its movement. Waves and hydrodynamic forces are obtained for both bottom mounted and truncated cylinders. The simulations have provided many results to show the nature of mutual interference between cylinders in arrays and its effects on waves and forces at the nearly trapped mode frequency. The effect of the tank wall on waves and forces has been investigated, and the nonlinear features of waves and forces have also been discussed.  相似文献   

双相介质瑞雷面波有限差分正演模拟   总被引：1，自引：0，他引：1  

张伟  甘伏平  刘伟  郑智杰 《物探与化探》2014,(6)

为了研究双相介质瑞雷面波的形成机制及传播规律,促进瑞雷面波资料处理方法的发展。文章根据弹性波动方程,采用交错网格有限差分算法,对二维各向同性弹性介质做解析解与数值解的对比,在此基础上,将PML吸收边界条件,改进的镜像法应用于双相介质波动方程中,并作了稳定性分析,对双相介质水平层状、起伏分界面等典型模型瑞雷面波及体波在内的全波场进行研究。结果表明:基于弹性介质解析解与数值解的对比,在误差接受范围内,研究双相介质是可行的;把稍作改进的镜像法应用于双相介质中,能够有效地处理瑞雷面波自由边界问题;通过详细分析双相介质瑞雷面波及体波在内的全波场的信息,对以双相介质为基础的地震波勘探有一定的指导作用。  相似文献   

基于DEM和水箱理论识别流域河网方法研究   总被引：2，自引：1，他引：1  

乔飞  张万顺  崔鹏  冯桃辉  陈晓清 《测绘科学》2006,31(4):95-97

本文应用水箱原理处理流域DEM数据中存在的洼地问题,提出流域河网识别及编码的新方法。首先,确定洼地网格,搜索洼地区域,计算洼地容量,根据水箱原理确定洼地出口,判断洼地的流向;然后,逐层合并消减洼地,修正洼地水流方向;最后,计算网格集水面积,进行河网识别和编码。本文结合云南东川蒋家沟流域的DEM资料进行河网识别,得到了完整的流域河网,结果与实际勘测的河网完全吻合,这表明应用该方法提取流域河网是可行的,能够为进一步的分布式水文、泥石流、环境模型提供条件。  相似文献   

An ocean wind-wave climatology for the Southern Brazilian Shelf. Part I: Problem presentation and model validation     

《Dynamics of Atmospheres and Oceans》2020

Geomorphological features and sparse visual wave measurements, presented in previous works, point out to the possible existence of alongshore wave energy gradients over the Southern Brazilian Shelf (SBS). After describing the two numerical models utilized and the model grids and settings, the present study evaluated the proposed validation of the basin-scale results against orbital altimetry and the regional-scale results against the two available wave-buoy data, discussing the extent to which the model reproduced local reality. The basin-scale model results of significant wave height could be considered as in good agreement with observations, presenting remarkable similarities with observed altimetry. Regarding the regional-scale modeling, both significant wave height and peak wave periods were considered as in good agreement with observations. The peak wave directions, however, were classified as in poor agreement, once the ESE waves were erroneously reproduced as E. Increased spatial resolution certainly played a role, but it was the lowering of bottom friction that represented the major improvement in the coastal grid simulations.  相似文献   

宁夏惠农区新农村典型供电模式应用研究     

黄涛  马斌  张江斌 《地下水》2011,33(5):132-134

针对当前农村电网建设中存在的问题,以宁夏惠农区为试点区域,开展新农村典型供电模式应用研究。分别从电网规划建设、电网运行控制及节能减耗等领域进行供电模式的需求分析,在新农村典型供电模式的基础上提出了惠农区典型供电模式与实施规模,实践表明典型供电模式在惠农区具有较好的应用效果。  相似文献   

两种网格下的SWAN模式对黄渤海海浪模拟比较     

史剑  王璞  钟中  张军 《海洋预报》2011,28(4):48-57

采用NCEP再分析风场作为驱动海浪模式的强迫场,在考虑相同物理过程和分辨率基础上,SWAN海浪模式分别采用矩形网格和非结构三角网格对2000年12月黄渤海海域波浪场进行模拟,并将模拟的有效波高与海洋浮标观测数据作对比分析,结果表明,SWAN模式运用两种网格均能够取得良好的模拟结果,相对矩形网格,非结构三角网格模拟有效波...  相似文献   

Computations of self-propulsion free to sink and trim and of motions in head waves of the KRISO Container Ship (KCS) model   总被引：2，自引：0，他引：2  

Pablo M. Carrica  Huiping Fu  Frederick Stern 《Applied Ocean Research》2011,33(4):309-320

Two computations of the KCS model with motions are presented. Self-propulsion in model scale free to sink and trim are studied with the rotating discretized propeller from the Hamburg Model Basin (HSVA) at Fr = 0.26. This case is particularly complex to simulate due to the close proximity of the propeller to the rudder. The second case involves pitch and heave in regular head waves. Computations were performed with CFDShip-Iowa version 4.5, a RANS/DES CFD code designed for ship hydrodynamics. The self-propulsion computations were carried out following the procedure described in Carrica et al. [1], in which a speed controller is used to find the propeller rotational speed that results in the specified ship velocity. The rate of revolutions n, sinkage, trim, thrust and torque coefficients K_T, K_Q and resistance coefficient CT_(SP) are thus obtained. Comparisons between CFD and EFD show that the rate of revolutions n, thrust and torque coefficients K_T and K_Q have higher prediction accuracies than sinkage and trim. For the simulation of pitch and heave in head waves, the geometry includes KCS hull and rudder under three conditions with two Froude numbers and three wave length and amplitude combinations. 0th and 1st harmonic amplitudes and 1st harmonic phase are computed for total resistance coefficient C_T, heave motion z and pitch angle θ. Comparisons between CFD and EFD show that pitch and heave are much better predicted than the resistance. In both cases comparisons with simulations by other authors presented at the G2010 CFD Workshop [2] using different CFD methodologies are included.  相似文献   

基于GIS的姓氏地名制图方法研究     

吴增伟  张胜茂 《测绘科学》2011,36(4):178-180

地名研究能够揭示地名所固有的科学价值,为科学研究提供重要依据,地名制图法是地名研究中常用的方法,用它分析姓氏地名可以追述某姓氏起源,了解该姓氏人口的分布、迁移等.本文借助GIS软件,对张姓地名进行了分析,采用的格网制图数据分析,可以反映张姓村庄的密集程度、密度值连续变化状况、宏观分布规律;空间平滑插值制图数据分析,可以...  相似文献