检索结果-南通市图书馆

Generalized Multiscale Finite Element *** Elliptic Equations

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Communications in Computational Physics 2014年第3期15卷 733-755页

作者： yalchin efendiev Juan Galvis Guanglian Li Michael Presho Center for Numerical Porous Media(NumPor) King Abdullah University of Science and Technology(KAUST)Thuwal 23955-6900Kingdom of Saudi Arabia Department of Mathematics&Institute for Scientific Computation(ISC) Texas A&M UniversityCollege StationTexas 77843USA Departamento de Matem´aticas Universidad Nacional de ColombiaBogot´a D.C.Colombia

In this paper we use the Generalized Multiscale Finite Element Method(GMsFEM)framework,introduced in[26],in order to solve nonlinear elliptic equations with high-contrast *** proposed solution method involves linearizing the equation so that coarse-grid quantities of previous solution iterates can be regarded as auxiliary parameters within the problem *** this convention,we systematically construct respective coarse solution spaces that lend themselves to either continuous Galerkin(CG)or discontinuous Galerkin(DG)global ***,we use Symmetric Interior Penalty Discontinuous Galerkin *** methods yield a predictable error decline that depends on the respective coarse space dimension,and we illustrate the effectiveness of the CG and DG formulations by offering a variety of numerical examples.

关键词： Generalized multiscale finite element method nonlinear equations high-contrast

Multilevel Markov Chain Monte Carlo Method for High-Contrast Single-Phase Flow Problems

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Communications in Computational Physics 2015年第1期17卷 259-286页

作者： yalchin efendiev Bangti Jin Michael Presho Xiaosi Tan Department of Mathematics Texas A&M UniversityCollege StationTX 77843-3368USA SRI Center for Numerical Porous Media(NumPor) King Abdullah University of Science and Technology(KAUST)Thuwal 23955-6900Kingdom of Saudi Arabia Department of Computer Science University College LondonGower StreetLondon WC1E 6BTUK

In this paper we propose a general framework for the uncertainty quantification of quantities of interest for high-contrast single-phase flow *** is based on the generalized multiscale finite element method(GMsFEM)and multilevel Monte Carlo(MLMC)*** former provides a hierarchy of approximations of different resolution,whereas the latter gives an efficient way to estimate quantities of interest using samples on different *** number of basis functions in the online GMsFEM stage can be varied to determine the solution resolution and the computational cost,and to efficiently generate samples at different *** particular,it is cheap to generate samples on coarse grids but with low resolution,and it is expensive to generate samples on fine grids with high *** suitably choosing the number of samples at different levels,one can leverage the expensive computation in larger fine-grid spaces toward smaller coarse-grid spaces,while retaining the accuracy of the final Monte Carlo ***,we describe a multilevel Markov chain Monte Carlo method,which sequentially screens the proposal with different levels of approximations and reduces the number of evaluations required on fine grids,while combining the samples at different levels to arrive at an accurate *** framework seamlessly integrates the multiscale features of the GMsFEM with the multilevel feature of the MLMC methods following the work in[26],and our numerical experiments illustrate its efficiency and accuracy in comparison with standard Monte Carlo estimates.

关键词： Generalized multiscale finite element method multilevel Monte Carlo method multilevel Markov chain Monte Carlo uncertainty quantification

Multiscale Finite ElementMethods for Flows on Rough Surfaces

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Communications in Computational Physics 2013年第9期14卷 979-1000页

作者： yalchin efendiev Juan Galvis M.Sebastian Pauletti Department of Mathematics TAMUCollege StationTX 77843-3368USA Departamento de Matematicas Universidad Nacional de ColombiaBogotaColombia

In this paper,we present the Multiscale Finite Element Method(MsFEM)for problems on rough heterogeneous *** consider the diffusion equation on oscillatory *** objective is to represent small-scale features of the solution via multiscale basis functions described on a coarse *** problem arises in many applications where processes occur on surfaces or thin *** present a unified multiscale finite element framework that entails the use of transformations that map the reference surface to the deformed *** main ingredients of MsFEM are(1)the construction of multiscale basis functions and(2)a global coupling of these basis *** the construction of multiscale basis functions,our approach uses the transformation of the reference surface to a deformed *** the deformed surface,multiscale basis functions are defined where reduced(1D)problems are solved along the edges of coarse-grid blocks to calculate nodalmultiscale basis ***,these basis functions are transformed back to the reference *** discuss the use of appropriate transformation operators that improve the accuracy of the *** method has an optimal convergence if the transformed surface is smooth and the image of the coarse partition in the reference configuration forms a quasiuniform *** this paper,we consider such transformations based on harmonic coordinates(following *** and ***[*** and Applied Math.,LX(2007),pp.675-723])and discuss gridding issues in the reference *** results are presented where we compare the MsFEM when two types of deformations are used formultiscale basis *** first deformation employs local information and the second deformation employs a global *** numerical results showthat one can improve the accuracy of the simulations when a global information is used.

关键词： Multiscale finite elements on surfaces Laplace Beltrami resonance error harmonic maps

Time-Lapse 3-D Seismic Wave Simulation via the Generalized Multiscale Finite Element Method

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Communications in Computational Physics 2020年第6期28卷 401-423页

作者： Yongchae Cho Richard L.Gibson,Jr. Hyunmin Kim Mikhail Artemyev yalchin efendiev Shell International Exploration&Production Inc. 150 N Dairy Ashford RoadHoustonTX 77079USA Department of Geology&Geophysics Texas A&M UniversityCollege StationTexas 77843-3115USA Shell Exploration&Production Company 701 Poydras StreetNew OrleansLA 70139USA Arista Networks DublinIreland Department of Mathematics Texas A&M UniversityCollege StationTexas 77843-3368USA Multiscale Model Reduction Laboratory North-Eastern Federal UniversityYakutskRepublic of Sakha 677980Russia

Numerical solution of time-lapse seismic monitoring problems can be challenging due to the presence of finely layered *** wave modeling using fine layered meshes also adds more computational *** approaches such as finite difference and finite element methods may be prohibitively expensive if the whole domain is discretized with the cells corresponding to the grid in the reservoir subdomain.A common approach in this case is to use homogenization techniques to upscale properties of subsurface media and assign the background properties to coarser grid;however,inappropriate application of upscaling might result in a distortion of the model,which hinders accurate monitoring of the fluid change in *** this work,we instead investigate capabilities of a multiscale method that can deal with fine scale heterogeneities of the reservoir layer and more coarsely meshed rock properties in the surrounding domains in the same *** address the 3-D wave problems,we also demonstrate how the multiscale wave modeling technique can detect the changes caused by fluid movement while the hydrocarbon production activity proceeds.

关键词： Fluid simulation time lapse Generalized multiscale finite element elastic wave

基于均匀化理论的页岩基岩运移机制尺度升级研究

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

中国科学：物理学、力学、天文学 2017年第11期47卷 115-124页

作者：孙海姚军 yalchin efendiev 中国石油大学(华东)石油工程学院青岛266580 Department of Mathematics Texas A & M University

基岩孔隙是页岩气藏的主要储集空间.页岩有机质孔隙和非有机孔隙具有不同的赋存方式和传输机制:有机质孔隙存在吸附气、游离气两种赋存方式,无机质内仅存在游离气,气体在有机质孔隙存在吸附解吸和吸附气的表面扩散.传统的数值模拟方法... 详细信息

基岩孔隙是页岩气藏的主要储集空间.页岩有机质孔隙和非有机孔隙具有不同的赋存方式和传输机制:有机质孔隙存在吸附气、游离气两种赋存方式,无机质内仅存在游离气,气体在有机质孔隙存在吸附解吸和吸附气的表面扩散.传统的数值模拟方法未考虑页岩基岩内不同孔隙介质储集方式和运移机制的差异性,未考虑有机质分布结构特征的影响.本文基于均匀化理论建立了考虑页岩基岩有机质分布特征和相应运移机制的尺度升级数学模型,在小尺度模型中考虑有机质和无机质赋存方式和运移机制的差异性.数值模拟结果表明,传统上具有相同宏观运移参数的基岩,若其有机质分布不同,采用尺度升级后的宏观模型计算的压力变化和产量均不同,必须进行尺度升级才能实现复杂结构分布的页岩基岩模拟的准确性.

关键词：页岩气均匀化理论运移机制尺度升级