An unstructured-grid, finite-volume, nonhydrostatic, parallel coastal ocean simulator   总被引：4，自引：4，他引：4  

O.B. Fringer  M. Gerritsen  R.L. Street   《Ocean Modelling》2006,14(3-4):139-173

A finite-volume formulation is presented that solves the three-dimensional, nonhydrostatic Navier–Stokes equations with the Boussinesq approximation on an unstructured, staggered, z-level grid, with the goal of simulating nonhydrostatic processes in the coastal ocean with grid resolutions of tens of meters. In particular, the code has been developed to simulate the nonlinear, nonhydrostatic internal wave field in the littoral ocean. The method is based on the formulation developed by Casulli, in that the free-surface and vertical diffusion are semi-implicit, thereby removing stability limitations associated with the surface gravity wave and vertical diffusion terms. The remaining terms in the momentum equations are discretized explicitly with the second-order Adams–Bashforth method, while the pressure-correction method is employed for the nonhydrostatic pressure in order to achieve overall second-order temporal accuracy. Advection of momentum is accomplished with an Eulerian discretization which conserves momentum in cells that do not contain the free surface, and scalar advection is discretized in a way that ensures consistency with continuity, thereby ensuring local and global mass conservation using a velocity field that conserves volume on a local and global basis. The nonhydrostatic pressure field is solved efficiently using a block-Jacobi preconditioner, and while stability is limited by the internal gravity wave speed and vertical advection of momentum, applications requiring relatively small time steps due to accuracy or stability constraints are run efficiently on parallel computers, since the present formulation is written entirely with the message-passing interface (MPI). The ParMETIS libraries are employed in order to achieve a load-balanced parallel partitioning that minimizes interprocessor communication, and the grid is reordered to optimize per-processor performance by limiting cache misses while accessing arrays in memory. Test cases demonstrate the ability of the code to efficiently and accurately compute the nonhydrostatic lock exchange and internal waves in idealized as well as real domains, and we evaluate the parallel efficiency of the code using up to 32 processors.  相似文献   

煤岩有机质成油、成气热模拟动力学模型及其标定   总被引：8，自引：0，他引：8       下载免费PDF全文

卢双舫  付晓泰  王振平  曲佳燕 《地质科学》1996,31(1):15-21

借助热解实验技术和PY-GC分析技术分别建立了有机质成油和成气的动力学模型,并在数学优化求解上作了比较深入的工作。所得模型的理论计算值与实验结果在不同条件下均有良好的吻合关系,初步显示了该模型的可行性及其应用前景。  相似文献   

干涉SAR的二维相位展开算法研究   总被引：3，自引：0，他引：3  

唐健  王贞松 《遥感学报》1997,1(3):172-177,241

该文讨论了干涉合成孔径雷达的二维相位展开算法。先简要给出了ＩＮＳＡＲ相位差图误差的统计特性，并说明了该误差可以近似为高斯型噪声。然后介绍了利用ＦＦＴ的最小二乘和二维相位展开算法，实验表明ＬＳ－ＦＦＴ算法对高斯白噪声具有很好的抗干扰性。  相似文献   

基于多源数据的山地地貌数字解译   总被引：2，自引：1，他引：2  

姚永慧  周成虎  孙然好  龙恩  朱运海  李炳元 《山地学报》2007,25(1):122-128

“3S”技术与地学的结合,对传统地貌制图的编绘方法必然产生较大影响。遥感影像不仅作为地面调查的重要辅助手段,而且是一种可以根据需要缩放到所需比例尺的重要数据源;各种数据源的参考数据如地形图、植被图、地质图、土地资源图等均可以数字的方式在GIS环境中集成、叠加与运算,从而改变了地貌制图依赖于地形图进行多次综合概括的制图方式,使基于多源数据的遥感地貌信息定量解译成为可能。以青藏高原昌都幅遥感地貌解译为例,探讨不同类型的数据在山地地貌解译过程中的使用方式和对地貌判读的作用,并在此基础上总结基于多源数据的遥感地貌解译方法,为全国1∶100万地貌遥感解译和地貌信息系统的建立奠定基础。  相似文献   

大规模数据并行问题的可扩展性分析          下载免费PDF全文

金之雁  王鼎兴 《应用气象学报》2003,14(3):369-374

大规模数据并行处理的性能受到处理机数量、I/O速度、通信速度等多方面因素的制约。增加处理机数量或提高处理机的计算速度，可以提高计算机的整体处理速度，但是通信和I/O会成为影响并行效率的主要因素。为了综合分析这些因素对计算性能的影响，用一种比较典型的大规模数据并行的计算模型，具体分析了处理机数量、处理机速度与处理机间的通信延迟、通信速率以及输入输出速度之间的关系。得到了大规模并行机的通信和I/O性能与处理机速度与数量之间存在的关系。指出，增加处理机数量、提高单节点处理速度的同时，必须按照一定的关系相应增加节点间的通信性能和I/O性能。单纯以增加处理机数量、提高单处理机速度提高计算机峰值速度的方法会降低系统的计算效率，不能达到计算速度与计算机处理能力同步增长的目的。  相似文献   

地震激发地球自由振荡过程的数值模拟初步探索   总被引：2，自引：0，他引：2  

严珍珍  张怀  杨长春  石耀霖 《地球科学进展》2008,23(10):1020-1026

地球自由振荡的固有频率与地球内部结构密切相关,研究地球自由振荡可以深入研究地球内部结构。传统的解析方法侧重于本征频率的确定,但对从地震发生到地球自由振荡被激发的全过程难以研究。从弹性波动理论基础出发,试采用谱元法结合高性能并行计算数值模拟特大地震激发的弹性波在地球内部传播过程。在不考虑地球重力情况下,对数值模拟激发地球自由振荡的结果进行功率谱密度分析,通过对谱结果的观察并与理论值进行对比分析,认识到环型振型数值模拟结果可以准确重现其长周期理论频率值,地球重力对球型振型有重要影响。探讨了是否可以通过这种方法真实重现地球自由振荡激发的过程。以期利用此方法深入探讨地球横向不均匀性对地球自由振荡的影响。  相似文献   

Parallel visualization of seismic wave propagation     

Huai Zhang  Shaolin Chen  Shi Chen  Si Chen  Huimin Jing  David A. Yuen  Yaolin Shi 《Visual Geosciences》2008,13(1):117-124

Today parallel visualization of massive datasets from observation and numerical simulation of seismic waves is one of the major goals of geoscience community. A majority of these datasets are time-varying volume data (TVVD), also known as 4D field data. The difficulty of visualizing them on distributed parallel system mainly lies in the algorithm designing for distributed preprocessing of raw datasets, hierarchical point-to-point or collective communication implementation based on distributed data allocation, synchronous volume rendering techniques. In this work we present viable solutions for preprocessing of raw data sets, novel algorithms of parallel rendering and display matrix. Our main objective is focused on the parallel visualization of results coming from full 4D seismic wave propagation simulations.  相似文献   

Global SH-wave propagation in a 2D whole Moon model using the parallel hybrid PSM/FDM method     

Xianghua Jiang  Yanbin Wang  Yanfang Qin  Hiroshi Takenaka 《地震科学（英文版）》2015,28(3):163-174

We present numerical modeling of SH-wave propagation for the recently proposed whole Moon model and try to improve our understanding of lunar seismic wave propagation. We use a hybrid PSM/FDM method on staggered grids to solve the wave equations and implement the calculation on a parallel PC cluster to improve the computing efficiency. Features of global SH-wave propagation are firstly discussed for a 100-km shallow and 900-km deep moonquakes, respectively. Effects of frequency range and lateral variation of crust thickness are then investigated with various models. Our synthetic waveforms are finally compared with observed Apollo data to show the features of wave propagation that were produced by our model and those not reproduced by our models. Our numerical modeling show that the low-velocity upper crust plays significant role in the development of reverberating wave trains. Increasing frequency enhances the strength and duration of the reverberations. Surface multiples dominate wavefields for shallow event. Core–mantle reflections can be clearly identified for deep event at low frequency. The layered whole Moon model and the low-velocity upper crust produce the reverberating wave trains following each phases consistent with observation. However, more realistic Moon model should be considered in order to explain the strong and slow decay scattering between various phases shown on observation data.  相似文献   

Chromophoric Dissolved Organic Matter Fluctuation Assessment in an Urban River          下载免费PDF全文

Yuting Liang  Erdeng Du  Chengjie Song  Chaopeng Song  Yuan Zhao  Xiang Liu 《洁净——土壤、空气、水》2015,43(8):1128-1135

  相似文献   

大地电磁三维交错网格有限差分数值模拟的并行计算研究   总被引：3，自引：3，他引：0  

李焱  胡祥云  杨文采  魏文博  方慧  韩波  彭荣华 《地球物理学报》2012,55(12):4036-4043

为了更有效的提高大地电磁三维正演的计算速度,引入了并行处理技术.大地电磁三维交错网格有限差分数值模拟是按照不同频率来计算的,各频率之间求取电磁场值的过程是相互独立的.根据这一特点,可以将多个频率的计算任务平均划分为一个或者几个频率的计算子任务,分配到各个计算节点去并行执行,计算完成后将结果汇总.本文通过采用主从并行模式、分频并行计算的方案,在曙光TC5000A高性能并行平台上实现了基于MPI的大地电磁三维正演的并行计算.通过两个理论模型对实现的大地电磁三维正演并行算法进行试算,对比分析了多个节点机下程序的执行效率.测试结果表明,所实现的三维正演并行算法是正确的、高效的,为进一步的大地电磁三维反演并行算法研究奠定了重要基础.  相似文献