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  • 1
    Online Resource
    Online Resource
    Newark :John Wiley & Sons, Incorporated,
    Keywords: Porous materials. ; Electronic books.
    Type of Medium: Online Resource
    Pages: 1 online resource (407 pages)
    Edition: 1st ed.
    ISBN: 9781118762059
    Language: English
    Note: Cover -- Half-Title page -- Dedication -- Title Page -- Copyright Page -- Contents -- List of Symbols -- Introduction -- I.1. Introduction -- Upscaling -- I.2. Organization of the text -- I.3. Objectives, contents, and readership -- Intended readership -- Brief guide to the topics of this book -- I.4. Acknowledgments -- 1. Fluids, Porous Media and REV: Basic Concepts -- 1.1. Geologic porous media: basic concepts -- 1.1.1. Porous soils -- 1.1.2. Porous rocks -- 1.1.3. Geologic porous media: examples -- 1.2. Porous media: basic concepts, porosity and specific area -- 1.2.1. Fluid phases -- 1.3. Single-phase flow and Darcy's law: basic concepts -- 1.3.1. Darcy's flux-gradient law -- 1.4. The Darcy-Buckingham law and the Richards equation: basic concepts of unsaturated flow -- 1.4.1. Remarks on unsaturated water flow -- 1.5. Capillarity and two-phase flow systems at different scales: basic concepts -- 1.5.1. Introduction -- 1.5.2. Capillarity pressure jump at different scales -- 1.5.3. Moving from one scale to another: upscaling -- 1.6. A basic approach to pore scale two-phase flow -- 1.7. A basic approach for continuum scale description of two-phase flow in porous media: the Darcy-Muskat model -- 1.7.1. The Buckey-Leverett model -- 1.8. Other issues: capillarity vs. gravity and viscosity, heterogeneity and upscaling -- 1.8.1. Capillarity plus gravity and viscous dissipation -- 1.8.2. Scales and the representative elementary volume -- 1.8.3. Objectives at various scales of analysis -- 1.8.4. Upscaling: first and second upscaling problems -- 2. Two-Phase Physics: Surface Tension, Interfaces, Capillary Liquid/Vapor Equilibria -- 2.1. Summary and objectives -- 2.2. Physics of capillarity and surface tension at equilibrium -- 2.2.1. Observations and practical applications of surface tension, capillary forces and contact angles. , 2.2.2. Interfacial tension: from molecular scale to fluid scale -- 2.2.3. Laplace-Young pressure jump law (capillary pressure) -- 2.2.4. Solid/liquid contact angle θ at equilibrium (Young) -- 2.2.5. Measurements of interfacial tension -- 2.2.6. Immiscibility versus miscibility at fluid interfaces (examples) -- 2.3. Dimensionless groups (characteristic forces, length scales, timescales) -- 2.3.1. Introduction: three forces driving multiphase systems -- 2.3.2. Reynolds and Reynolds-Darcy number, viscous dissipation -- 2.3.3. Capillary forces, surface tension and capillary number Ca -- 2.3.4. Gravitational buoyancy forces and the Bond number Bo -- 2.3.5. Dimensionless contrast ratios (viscosity and density contrasts) -- 2.3.6. Recap of dimensionless groups for a two-phase system -- 2.4. Thermodynamics, Gibbs energy, pressure, suction -- 2.4.1. Interpretation of large suctions, bonding forces and Gibbs energy -- 2.4.2. Thermodynamical systems (isolated or not) -- 2.4.3. Gibbs free energy, heat, work -- 2.5. Kelvin's liquid/vapor relation (suction vs. air humidity) -- 2.5.1. Introduction to Kelvin's law (applications in flow modelin) -- 2.5.2. Qualitative discussion of Kelvin's law (liquid/vapor relations) -- 2.5.3. Thermodynamical variables (pressure, air humidity, etc.) -- 2.5.4. Perfect gases (dry air and water vapor) -- 2.5.5. Kelvin's law: relative air humidity vs. capillary pressure -- 2.5.6. Extended discussion on liquid/vapor thermodynamics (review) -- 3. Capillary Equilibria in Pores, Tubes and Joints -- 3.1. Introduction and summary -- 3.2. Capillary equilibrium in a single tube or planar joint of constant diameter or aperture -- 3.2.1. Introduction: problem formulation and notations -- 3.2.2. Capillary tube: pressure jump (Laplace-Young) -- 3.2.3. Capillary tube: water height (Jurin). , 3.2.4. Capillary tube: extensions and examples (other fluids, etc.) -- 3.2.5. Example of water/air equilibrium in a capillary tube: calculation of water height for a tube of diameter 100 μm -- 3.2.6. Planar joint: introduction - planar geometry of the meniscus -- 3.2.7. Planar joint: pressure jump across the water/air meniscus -- 3.2.8. Planar joint: equilibrium height of meniscus (capillary rise) -- 3.2.9. Example: parameter values for water and "light oil" in a joint -- 3.3. Capillary equilibria in variable tubes and joints (a(x)) -- 3.3.1. Introduction, description of the problem, and hypotheses -- 3.3.2. Non-existence of two-phase equilibria, depending on initial state -- 3.3.3. Geometric correction for variable tubes/joints: wetting angle θ + ϕ(x) in a fixed frame -- 3.4. Capillary equilibrium in a random set of tubes: calculation of water retention curve θ(ψ) -- 3.4.1. Introduction and summary -- 3.4.2. Capillary water/air equilibrium in a random set of "pores" -- moisture retention curve θ(pC) for uniformly distributed radii -- 3.4.3. Capillary water/air equilibrium and moisture retention curve θ(pc) for Pareto distributed radii with exponent ω = 2 -- 3.4.4. Limitations of the Boolean model of random tubes -- 3.4.5. Soil water retention curves in hydro-agriculture (overview) -- 3.5. Capillary equilibrium of soap films: minimal area surfaces and Euler-Lagrange equations -- 3.5.1. Introduction and summary -- 3.5.2. Soap film surface (preliminary formulation) -- 3.5.3. Euler-Lagrange equations for minimizing integrals -- 3.5.4. Euler-Lagrange equation minimizing the area -- 3.6. Case study of soap film equilibrium between two circular rings: minimal area surface (catenoid) -- 3.6.1. Presentation of the case study: soap film between two rings -- 3.6.2. Formulation: minimal area surface between two coaxial circles. , 3.6.3. Expressing Euler-Lagrange for the generating curve Y(x) -- 3.6.4. Solution of Euler-Lagrange equations: catenoid surface between two coaxial circles of different diameters -- 3.6.5. A special solution of the Euler-Lagrange equations: the catenoid surface between two identical coaxial rings -- 3.6.6. Parametric study and conclusions (existence/unicity of the soap film depending on ring geometry) -- 3.7. Additional topic: the equilibrium depth of a bubble -- 4. Pore-Scale Capillary Flows (Tubes, Joints) -- 4.1. Introduction and summary: pore-scale flow in capillary tubes and planar joints (steady and transient) -- 4.1.1. Introduction and summary -- 4.1.2. Case of steady flow systems (single phase and two phase) -- 4.1.3. Remark on the quasi-static nature of the water retention curve -- 4.1.4. Case of transient flow problems -- 4.1.5. Numerical experiment (2D visco-capillary invasion) -- 4.2. Single-phase steady flow in tubes: Poiseuille, Darcy, Kozeny-Carman permeability -- 4.2.1. Overview: Stokes, Poiseuille, Specific Area, Darcy, Kozeny permeability -- 4.2.2. Specific area concept -- 4.2.3. Poiseuille flow in a cylindrical tube or a planar joint -- 4.2.4. Kozeny-Carman permeability for single-phase flow (from Poiseuille to Darcy) -- 4.3. Unsaturated and two-phase steady flow in sets of planar joints: equivalent mesoscale quantities (porosity φ, permeability k, capillary length λcap) -- 4.3.1. Summary and overview -- 4.3.2. Upscaling unsaturated flow through a set of joints (equivalent permeability, porosity, and capillary length) -- 4.3.3. Upscaling two-phase flow in smooth or rough statistical joints: water retention θ(pc) -- conductivity curves {KW(pc), KNW(pc)} -- 4.3.4. Unsaturated or two-phase constitutive curves from statistical pore-scale models (discussion, review). , 4.4. Transient two-phase visco-capillary dynamics: interface motion X(t) in axially uniform or variable tubes/joints -- 4.4.1. Introduction, objectives, and literature review -- 4.4.2. Eulerian/Lagrangian equations for transient two-phase flow: axial interface displacement in tubes and joints -- 4.4.3. Quasi-analytical results on transient dynamics of immiscible fluids: axial displacement in variably constricted tubes and joints -- 4.4.4. Geometrical correction on interface dynamics X(t) in the case of very rough, highly variable tubes or joints (remarks) -- 4.4.5. Interface dynamics X(t) in tubes, pores, joints (prospects) -- 4.5. Two-dimensional two-phase dynamics: transient drainage in a planar joint with randomly variable aperture field a(x,y) -- 4.5.1. Introduction and summary -- 4.5.2. The 2D "rough fracture" and its random aperture field a(x,y) -- 4.5.3. The 2D synthetic drainage experiment (two-phase flow) -- 4.6. Other transient capillary phenomena in fluid dynamics: waves, bubbles, etc. (brief indications) -- 4.6.1. Capillary waves -- 4.6.2. Rayleigh-Plateau instability -- 4.6.3. Bubble dynamics and cavitation -- 4.6.4. Liquid/vapor phase changes, boiling, bubbles in porous media -- 5. Darcy-Scale Capillary Flows in Heterogeneous or Statistical Continua (Richards and Muskat) -- 5.1. Introduction, objectives and applications -- 5.1.1. Introduction and summary -- 5.1.2. Flow regimes and potential applications -- 5.1.3. Hierarchy of scales and related issues (discontinuities) -- 5.1.4. Material discontinuities in Darcy-scale flows -- 5.2. Concepts: porous media, Darcy scale and REV (revisited) -- 5.3. Single-phase Darcy-scale continuum flow equations (Navier-Stokes, Poiseuille, Darcy) -- 5.3.1. Introduction and summary -- 5.3.2. Darcy's law: from Navier-Stokes to Darcy in a nutshell. , 5.3.3. Darcy's law for isotropic media (scalar permeability, single phase flow).
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  • 2
    Online Resource
    Online Resource
    Singapore : Springer Nature Singapore | Singapore : Imprint: Springer
    Keywords: Computer science. ; Differential equations. ; Pollution. ; System theory. ; Mathematical models.
    Description / Table of Contents: Introduction, objectives -- Overview of uncertainty propagation methods -- Review of Probabilistic versus Fuzzy Approaches to Uncertainty Propagation in Geosciences -- Fuzzy set characterization of uncertainty (fuzzy variables) -- Applications of uncertainty analyses on simplified models -- Applications of uncertainty analysis to 3D subsurface contamination problems -- Discussion and conclusions.
    Type of Medium: Online Resource
    Pages: 1 Online-Ressource(IX, 95 p. 31 illus., 27 illus. in color.)
    Edition: 1st ed. 2023.
    ISBN: 9789819962419
    Series Statement: SpringerBriefs in Applied Sciences and Technology
    Language: English
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  • 3
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Karstic systems are highly heterogeneous geological formations characterized by a multiscale temporal and spatial hydrologic behavior with more or less localized temporal and spatial structures. Classical correlation and spectral analyses cannot take into account these properties. Therefore, it is proposed to introduce a new kind of transformation: the wavelet transform. Here we focus particularly on the use of wavelets to study temporal behavior of local precipitation and watershed runoffs from a part of the karstic system. In the first part of the paper, a brief mathematical overview of the continuous Morlet wavelet transform and of the multiresolution analysis is presented. An analogy with spectral analyses allows the introduction of concepts such as wavelet spectrum and cross-spectrum. In the second part, classical methods (spectral and correlation analyses) and wavelet transforms are applied and compared for daily rainfall rates and runoffs measured on a French karstic watershed (Pyrenees) over a period of 30 years.Different characteristic time scales of the rainfall and runoff processes are determined. These time scales are typically on the order of a few days for floods, but they also include significant half-year and one-year components and multi-annual components. The multiresolution cross-analysis also provides a new interpretation of the impulse response of the system. To conclude, wavelet transforms provide a valuable amount of information, which may be now taken into account in both temporal and spatially distributed karst modeling of precipitation and runoff.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1573-8868
    Keywords: tracer transport ; random media ; stratified media ; multilayered media ; macrodispersion ; Lagrangian particle tracking
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract Dispersive mass transport processes in naturally heterogeneous geological formations (porous media) are investigated based on a particle approach to mass transport and on its numerical implementation using LPT3D, a Lagrangian Particle Tracking 3D code. We are currently using this approach for studying microscale and macroscale space–time behavior (advection, diffusion, dispersion) of tracer plumes, solutes, or miscible fluids, in 1,2,3-dimensional heterogeneous and anisotropic subsurface formations (aquifers, petroleum reservoirs). Our analyses are based on a general advection-diffusion model and numerical scheme where concentrations and fluxes are discretized in terms of particles. The advection-diffusion theory is presented in a probabilistic framework, and in particular, a numerical analysis is developed for the case of advective transport and rotational flows (numerical stability of the explicit Euler scheme). The remainder of the paper is devoted to the behavior of concentration, mass flux density, and statistical moments of the transported tracer plume in the case of heterogeneous steady flow fields, where macroscale dispersion occurs due to geologic heterogeneity and stratification. We focus on the case of perfectly stratified or multilayered media, obtained by generating many horizontal layers with a purely random transverse distribution of permeability and horizontal velocity. In this case, we calculate explicitly the exact mass concentration field C(x, t), mass flux density field f(x, t), and moments. This includes spatial moments and dispersion variance σ2 x (t) on a finite domain L, and temporal moments on a finite time scale T, e.g., the “mass variance” of arrival times σ2 T (x). The moments are related to flux concentrations in a way that takes explicitly into account finite space–time scales of analysis (time-dependent tracer mass; spatially variable “flow through” mass). The multilayered model problem is then used in numerical experiments for testing different ways of recovering information on tracer plume migration, dispersion, concentration and flux fields. Our analyses rely on a probabilistic interpretation that emerges naturally from the particle approach; it is based on spatial moments (particle positions), temporal moments (mass weighted arrival times), and probability densities (both concentrations and fluxes). Finally, as an alternative to direct estimations of the flux and concentration fields, we formulate and study the “Moment Inverse Problem.” Solving the MIP yields an indirect method for estimating the space–time distribution of flux concentrations based on observed or estimated moments of the plume. The moments may be estimated from field measurements, or numerically computed by particle tracking as we do here.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1573-1634
    Keywords: Flow in random media ; effective conductivity ; finite differences ; iterative methods ; large-scale simulations ; groundwater flow ; stochastic hydrology ; random functions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract This paper presents a numerical method for simulating flow fields in a stochastic porous medium that satisfies locally the Darcy equation, and has each of its hydraulic parameters represented as one realization of a three-dimensional random field. These are generated by using the Turning Bands method. Our ultimate objective is to obtain statistically meaningful solutions in order to check and extend a series of approximate analytical results previously obtained by a spectral perturbation method (L. W. Gelhar and co-workers). We investigate the computational aspects of the problem in relation with stochastic concepts. The difficulty of the numerical problem arises from the random nature of the hydraulic conductivities, which implies that a very large discretized algebraic system must be solved. Indeed, a preliminary evaluation with the aid of scale analysis suggests that, in order to solve meaningful flow problems, the total number of nodes must be of the order of 106. This is due to the requirement that Δx i ≪ gl i ≪ L i , where Δx i is the mesh size, λ i is a typical correlation scale of the inputs, and L i is the size of the flow domain (i = 1, 2, 3). The optimum strategy for the solution of such a problem is discussed in relation with supercomputer capabilities. Briefly, the proposed discretization method is the seven-point finite differences scheme, and the proposed solution method is iterative, based on prior approximate factorization of the large coefficient matrix. Preliminary results obtained with grids on the order of one hundred thousand nodes are discussed for the case of steady saturated flow with highly variable, random conductivities.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1573-8868
    Keywords: kriging ; condition number ; random fields ; conditional simulation ; covariance matrices ; state-space estimation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract The numerical stability of linear systems arising in kriging, estimation, and simulation of random fields, is studied analytically and numerically. In the state-space formulation of kriging, as developed here, the stability of the kriging system depends on the condition number of the prior, stationary covariance matrix. The same is true for conditional random field generation by the superposition method, which is based on kriging, and the multivariate Gaussian method, which requires factoring a covariance matrix. A large condition number corresponds to an ill-conditioned, numerically unstable system. In the case of stationary covariance matrices and uniform grids, as occurs in kriging of uniformly sampled data, the degree of ill-conditioning generally increases indefinitely with sampling density and, to a limit, with domain size. The precise behavior is, however, highly sensitive to the underlying covariance model. Detailed analytical and numerical results are given for five one-dimensional covariance models: (1) hole-exponential, (2) exponential, (3) linear-exponential, (4) hole-Gaussian, and (5) Gaussian. This list reflects an approximate ranking of the models, from “best” to “worst” conditioned. The methods developed in this work can be used to analyze other covariance models. Examples of such representative analyses, conducted in this work, include the spherical and periodic hole-effect (hole-sinusoidal) covariance models. The effect of small-scale variability (nugget) is addressed and extensions to irregular sampling schemes and higher dimensional spaces are discussed.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Transport in porous media 18 (1995), S. 199-201 
    ISSN: 1573-1634
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Type of Medium: Electronic Resource
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