共查询到20条相似文献,搜索用时 31 毫秒
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For the three-dimensional convection-dominated problem of dynamics of fluids in porous media, the second order upwind finite difference fractional steps schemes applicable to parallel arithmetic are put forward. Fractional steps techniques are needed to convert a multi-dimensional problem into a series of successive one-dimensional problems. Some techniques, such as calculus of variations, energy method, multiplicative commutation rule of difference operators, decomposition of high order difference operators, and the theory of prior estimates are adopted. Optimal order estimates are derived to determine the error in the second order approximate solution. These methods have already been applied to the numerical simulation of migration-accumulation of oil resources and predicting the consequences of seawater intrusion and protection projects. 相似文献
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For the system of multilayer dynamics of fluids in porous media, the second order upwind finite difference fractional steps schemes applicable to parallel arithmetic are put forward. Some techniques, such as calculus of variations, energy method, multiplicative commutation rule of difference operators, decomposition of high order difference operators and prior estimates are adopted. Optimal order estimates are derived to determine the error in the second order approximate solution. These methods have already been applied to the numerical simulation of migration-accumulation of oil resources. 相似文献
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驻定斜爆轰波并行数值模拟 总被引:1,自引:0,他引:1
采用多组分化学反应Euler方程组对驻定在高速飞行弹丸上的斜爆轰波流场进行了数值模拟。计算中分别采用TVD格式和基元反应模型,并基于并行编程模型MPI(message passing interface)实现了非结构网格上的并行计算,对流项和化学反应项用时间分裂法进行处理。计算结果表明并行计算能有效地提高计算速度,扩展计算规模,为进一步研究超驱爆轰推进技术奠定基础。 相似文献
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针对四个处理机的Transputer并行计算机系统,建立了建筑风压数值模拟问题基于SIM-PLEC算法的几种并行化策略:分区并行策略、方程并行策略和双重并行策略。对各种策略的计算流程、数据通讯及并行效率等进行了分析和比较,并通过实例计算作了验证。 相似文献
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IntroductionThenumericalsimulationoftheevolutionaryhistoryofthebasinisconductedacordingtothemechanismofpetroleumgeologyandmec... 相似文献
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A fractional step scheme with modified characteristic finite differences running in a parallel arithmetic is presented to simulate a nonlinear percolation system of multilayer dynamics of fluids in a porous medium with moving boundary values. With the help of theoretical techniques including the change of regions, piecewise threefold quadratic interpolation, calculus of variations, multiplicative commutation rule of difference operators, multiplicative commutation rule of difference operators, decomposition of high order difference operators, induction hypothesis, and prior estimates, an optimal order in l 2 norm is displayed to complete the convergence analysis of the numerical algorithm. Some numerical results arising in the actual simulation of migration-accumulation of oil resources by this method are listed in the last section. 相似文献
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Simulation and application of three-dimensional migration-accumulation of oil resources 总被引:1,自引:0,他引:1
IntroductionTheoilformationinsedimentbasins,itsdisplacement,transportandaccumulation,andthefinalformationofoildepositshavebeenthekeyproblemsintheexplorationofoil_gasresources.Howhasoilbeenaccumulatedinthepresentloopaccordingtothemechanicsofimmiscible… 相似文献
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An improved domain-decoupled compact scheme for first and second spatial derivatives is proposed for domain-decomposition-based parallel computational fluid dynamics. The method improves the accuracy of previously developed decoupled schemes and preserves the accuracy and bandwidth properties of fully coupled compact schemes, even for a very large degree of parallelism, and enables the Navier-Stokes equations to be solved independently on each processor. The scheme is analysed using Fourier analysis and error analysis, and tested on one-dimensional wave-packet propagation, a two-dimensional vortex convection problem, and in the direct numerical simulation of the three-dimensional Taylor-Green vortex problem and turbulent channel flow. Our results demonstrate the scheme's effectiveness in performing direct numerical simulation of turbulence in terms of accuracy and scalability. 相似文献
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岩质圆形隧洞围岩应力场弹塑性新解 总被引:1,自引:0,他引:1
针对动态接触问题的有限元并行计算,提出了一种新的接触算法. 新算法引入局部拉氏
乘子技术来计算接触力. 由于同时考虑了无穿透的接触约束条件和相邻接触对的相互影响,
较之广泛使用的罚参数法,新算法使接触约束条件和系统平衡方程得到更充分的满足. 虽然
为提高接触计算精度而在局部采用了迭代技术,但算法仍然具有较高的效率,且与显式时间
积分方案完全相容. 此外,通过构造专门的区域分解方案,实现了将现有为串行程序开发的
搜索算法平滑移植到并行环境的目标. 数值算例表明,所提出的接触算法具有很好的并行性,
在保证了接触问题并行计算精度的同时,取得了满意的并行效率. 相似文献
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高阶紧致格式分区并行算法 总被引:1,自引:0,他引:1
针对超声速多尺度复杂流动问题,发展了一种高精度并行算法。计算格式采用五阶迎风紧致格式,用特征型通量限制方法抑制非物理振荡。在对接边界处采用五阶WENO格式,以保证整个计算域内计算精度一致。通过网格分区和数据交换,在MPI平台实现了并行计算。通过超声速算例对算法进行了验证,并对并行效率和加速比进行了分析。最后,将算法应用于超声速转捩、湍流问题的数值模拟。计算结果表明,提出的算法具有较高的精度和分辨率,对接边界光滑连续,并且并行效率较高,在高超声速湍流流动数值模拟中取得了较好的应用效果。 相似文献
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混凝土细观力学分析程序中的快速算法与并行算法设计 总被引:1,自引:0,他引:1
针对一套混凝土细观力学分析程序,在分析其计算方法与计算效率的不足之后,提出了采用稀疏矩阵与稀疏向量技术来高效实现有限元刚度矩阵装配过程的算法,并采用双门槛不完全Cholesky分解预条件技术与CG法相结合来高效地求解稀疏线性方程组。之后,从整体上提出了一个将有限单元分布与未知量分布有机结合的并行算法设计方案,并分别针对刚度矩阵装配、双门槛不完全Cholesky分解、稀疏矩阵与稠密向量相乘、稀疏向量相加等核心算法,进行了相应的并行算法设计。最后,在由每节点2 CPU的8个Intel Xeon节点采用千兆以太网连成的机群上,针对两个混凝土数值试样进行了数值实验,第一个试样含44117个网格点与53200个有限单元,第二个试样含71013个网格点与78800个有限单元;对第一个试样,原串行程序进行全程567次加载计算需要984.83小时约41天,采用文中串行算法后,模拟时间减少到22531秒约6.26小时,采用并行算法在16个CPU上的模拟时间进一步降为3860秒约1.07小时。对第二个试样,原串行程序进行全程94次加载计算需要467.19小时约19.5天,采用文中串行算法后,模拟时间减少到11453秒约3.18小时,采用并行算法在16个CPU上的模拟时间进一步降为1704秒约28.4分钟。串行算法的改进与并行算法的设计大大缩短了计算时间,对加快混凝土力学性能的分析研究具有重要意义。 相似文献
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GPS/INS组合导航算法性能评估平台 总被引:1,自引:1,他引:1
针对常规GPS/INS组合导航算法研发系统扩展性较差的问题,研发了一种GPS/INS组合导航算法性能评估实验平台。该实验平台具有较高的开放性和可扩展性,能够比较便利地嵌入各种导航系统进行仿真数据实验、真实数据实验,完成算法性能的评估。文章首先介绍这一实验平台的基本结构,并给出了一些关键技术的解决方案,最后通过利用该平台进行仿真实验,结果验证了实验平台的GPS/INS组合导航算法性能评估是科学有效的。文章设计的多数据源导航模拟器和独立的算法库为今后的组合导航算法研究提供了有利的参考价值. 相似文献
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Environmental pollution and declining resources of fossil fuels in recent years, have increased demand for better fuel economy and less pollution for ground transportation. Among the alternative solutions provided by researchers in recent decades, hybrid electric vehicles consisted of an internal combustion engine and an electric motor have been considered as a promising solution in the short-term. In the present study, fuel economy characteristics of a parallel hybrid electric vehicle are investigated by using numerical simulation. The simulation methodology is based on a fast forward facing simulation model of a parallel hybrid and an internal combustion engine powertrains. The objective of this study is to present the main parameters which result in an optimum combination of hybrid powertrain components in order to obtain a better fuel economy of hybrid powertrains regarding different driven cycles and hybridization factors. Then, the fuel consumption of the parallel hybrid electric vehicles are compared considering various driven cycles and hybridization factors. The results showed that the better fuel economy of hybrid powertrains increases by decreasing average load of the test cycle and the point of the best fuel economy for a particular average load of the cycle moves towards higher hybridization factors when the average load of the test cycle is reduced. 相似文献
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神经网络辅助卡尔曼滤波技术在组合导航系统中的应用研究 总被引:3,自引:1,他引:2
考虑到组合导航系统的噪声具有非先验性,而传统的卡尔受滤波器要求假设动态模型和观测模型的噪声统计特性已知,提出了用前向神经网络来辅助调节卡尔受滤波器,使其具有自适应能力以应付动态环境的扰动。仿真研究表明:该算法优于标准卡尔曼滤波器。 相似文献
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The shock tube experiments of inclined air/SF6 interface instability under the shock wave with the Mach numbers 1.23 and 1.41 are conducted. The numerical simulation is done with the parallel algorithm and the multi-viscous-fluid and turbulence (MVFT) code of the large-eddy simulation (LES). The developing process of the interface accelerated by the shock wave is reproduced by the simulations. The complex wave structures, e.g., the propagation, refraction, and reflection of the shock wave, are clearly revealed in the flows. The simulated evolving images of the interface are consistent with the experimental ones. The simulated width of the turbulent mixing zone (TMZ) and the displacements of the bubble and the spike also agree well with the experimental data. Also, the reliability and effectiveness of the MVFT in simulating the problem of interface instability are validated. The more energies are injected into the TMZ when the shock wave has a larger Mach number. Therefore, the perturbed interface develops faster. 相似文献
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This paper presents a simple and efficient procedure developed for tracing discontinuities in flow fields. Numerical experiments are carried out to test the new sensor coupled with the associated nonlinear WENO dissipation filter developed to suppress the numerical dissipation. The tests show that, for a problem containing shocks and vortices, the implementation of the new sensor and an optimized WENO scheme can obtain a stable and highly resolved solution. The numerical experiments demonstrated that the new filter scheme performs efficiently both in parallel and serial running for one‐dimensional inviscid flow problems. Direct numerical simulation of a Mach 5 turbulent boundary layer over a flat plate was carried out to demonstrate the applicability of the scheme to the DNS practices. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献