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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Computing and visualization in science 3 (2000), S. 121-131 
    ISSN: 1433-0369
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract. Recently an operator splitting technique for convection diffusion equations, originating in porous medium flow, has been developed and analysed for one and two space dimensional models. The method is based on a solution of a modified hyperbolic problem which is used to approximate the original equation in a second step. The main objective of this paper is to investigate these algorithms for three dimensional porous media models, where handling of the gravity term is a main issue. The balance between the external pressure and the gravity may give a velocity field which is vanishing and may change sign in parts of the computational domain. This type of problem is dificult to solve accurately. Two different solution approaches are tested for accuracy, stability and computational costs.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Computational geosciences 2 (1998), S. 217-240 
    ISSN: 1573-1499
    Keywords: two-phase fluid flow ; discontinuous parameters ; discontinuous finite elements ; characteristic methods
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Computer Science
    Notes: Abstract Flow of fluids and transport of solutes in porous media are subjects of wide interest in several fields of applications: reservoir engineering, subsurface hydrology, chemical engineering, etc. In this paper we will study two-phase flow in a model consisting of two different types of sediments. Here, the absolute permeability, the relative permeabilities and the capillary pressure are discontinuous functions in space. This leads to interior boundary value problems at the interface between the sediments. The saturation Sw will be discontinuous or experience large gradients at the interface. A new solution procedure for such problems will be presented. The method combines the modified method of characteristics with a weak formulation where the basis functions are discontinuous at the interior boundary. The modified method of characteristics will provide a good first approximation for the jump in the discontinuous basis functions, which leads to a fast converging iterative solution scheme for the complete problem. The method has been implemented in a two-dimensional simulator, and results from numerical experiments will be presented.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Transport in porous media 23 (1996), S. 125-134 
    ISSN: 1573-1634
    Keywords: permeability ; upscaling ; flow prediction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract A method for upscaling of permeability in heterogeneous porous media is presented. The upscaled field takes the form K = e Y , where Y, in two dimensions, is a piecewise bilinear function. The method is tested on a number of random permeability fields, with different integral scale/correlation length and variance. The numerical results show that this method conserves much more of the heterogeneous fingering than classical block-based upscaling methods, e.g., geometric mean.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1572-9265
    Keywords: advection dominated problem ; domain decomposition ; 65N30
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract Two nonoverlapping domain decomposition algorithms are proposed for convection dominated convection–diffusion problems. In each subdomain, artificial boundary conditions are used on the inflow and outflow boundaries. If the flow is simple, each subdomain problem only needs to be solved once. If there are closed streamlines, an iterative algorithm is needed and the convergence is proved. Analysis and numerical tests reveal that the methods are advantageous when the diffusion parameter ɛ is small. In such cases, the error introduced by the domain decomposition methods is negligible in comparison with the error in the singular layers, and it allows easy and efficient grid refinement in the singular layers.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 38 (1995), S. 2017-2032 
    ISSN: 0029-5981
    Keywords: reservoir flow ; non-linear model ; gravity ; operator-splitting ; method of characteristics ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Based on a two-phase fluid model for immiscible displacement in a porous medium, we develop and analyse numerical solution techniques for certain non-linear phenomena. Two different solution strategies for the treatment of gravity effects, which are non-trivial to model by existing solution techniques and may be of great influence in many practical flow situations, are presented. The solution procedures are based on an operator-splitting technique, combining the modified method of characteristics with finite element techniques and adaptive grid refinement.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 34 (1992), S. 1051-1069 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Using a sequential time-marching approach, we describe and implement effective solution strategies for the equations governing immiscible displacement in a porous medium. By combining adaptive grid refinement with an operator-splitting technique based on the modified method of characteristics, the saturation equation is treated in a consistent and accurate way. For the pressure equation we construct accurate piecewise linear velocity components from a piecewise linear pressure approximation.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Communications in Applied Numerical Methods 4 (1988), S. 335-342 
    ISSN: 0748-8025
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The simulation of multiphase and multicomponent fluid flows often requires large coupled systems of nonlinear partial differential equations. These equations are convection-dominated, with important local diffusive effects. An operator splitting technique is used to address these different phenomena. Adaptive local grid refinement methods are then presented to resolve the moving internal boundary layers which arise and often govern the mass transfer between the phases. Owing to the large size of many application, efficiency in computation is critical. Concepts of domain decomposition for dynamic adaptive grid refinement are presented. Techniques for dividing the problems into pieces for parallel computation on separate processors are also discussed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Title: Domain decomposition methods in sciences and engineering : 9th international conference, Bergen Norway, 1996
    Contributer: Bjorstad, Petter E. , Espedal, Magne S. , Keyes, David E.
    Publisher: Bergen :Domain Decomposition Press,
    Year of publication: 1998
    Pages: 856 S.
    Type of Medium: Book
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