Author: David Anthony FarrellPublisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
An Assessment of the Role of Transient Flow on the Dispersion of Non-reactive Solutes in Porous Media
Dissertation Abstracts International
Author: Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 924
Book Description
Selected Water Resources Abstracts
Author: Dispersion Phenomena of Solutes and Particles and Their Applications in Porous Media
Author: Xiaoyan MengPublisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
Due to the special features, nanoparticles have seen various applications from drilling and completion as well as reservoir characterization to enhanced oil recovery (EOR). Not only does dispersion dominate solute and particle transport in both aquifers and hydrocarbon reservoirs, but also it imposes a significant impact on oil recovery during either chemical flooding or miscible gas injection processes for the injected agents. Considering the inherent heterogeneity and complex flow behaviour in porous media, therefore, it is of fundamental and practical importance to accurately describe dispersion of solutes and particles (including nanoparticles) in a uniform parallel-plate fracture and a circular tube. Also, this shall serve as a solid foundation for their applications to enhance oil recovery in fractured rocks and porous media. Besides, more efforts need to be extended to study solute and particle dispersion in porous media with different degrees of heterogeneity under various flow conditions. Using the moment analysis method and Green's function, mathematical formulations have been developed to determine dynamic dispersion coefficients for passive (i.e., chemically inert) and reactive (i.e., chemically active) particles flowing in a parallelplate fracture and a circular tube with fully-developed laminar flow under different source conditions across the full-time scale. These newly developed formulations have been verified for both solute and particle transport by agreeing well with analytical solutions and the random walk particle tracking (RWPT) simulations. Subsequently, the newly developed formulations for passive particles flowing in a parallel-plate fracture have been extended to match experimental measurements, while particle dispersion coefficients are notably less than those calculated by using the extended Taylor theory. For passive solutes and particles, at early times, dispersion coefficient is not only controlled by source condition, but also negatively correlated with center-of-mass velocity. After the critical time, source effect is negligible and all dispersion coefficients approach the values obtained through the extended Taylor theory. The relationship between particle size and dispersion coefficient for passive particles varies with time where they are positively correlated if Peclet number is larger than its critical value; otherwise, they are negatively correlated. As Damköhler number increases, for reactive particles, at long times, both reaction rate and center-of-mass velocity increase in magnitude, but dispersion coefficient decreases. At early times, however, those three parameters are not sensitive to Damköhler number. Consequently, reaction at the tube walls greatly affects concentration distribution. Coupling with the RWPT and pore-network modeling simulation, it is found that particle dispersion is greatly affected by particle size in a homogeneous model; however, for a heterogeneous model, throat velocity difference caused by heterogeneity plays an important role. In a homogeneous model, dispersion coefficient of particles (i.e., 7 dp 5 10 m) is overestimated without size exclusion, while the size-exclusion effects become more important as flow rate increases. In the heterogeneous models, however, size-exclusion effects of particles can be neglected. The dispersion difference between volumetric and uniform distributions increases with particle size and heterogeneity of the pore-network model. For a homogeneous model, dispersion coefficient with uniform distribution leads to a larger value than that with volumetric distribution; however, as heterogeneity increases, dispersion coefficient with volumetric distribution shows a larger value.
Flow And Transport In Porous Media - Proceedings Of The Summer School
Author: Brian Howard GildingPublisher: World Scientific
ISBN: 9814507334
Category : Science
Languages : en
Pages : 376
Book Description
Contents:Mathematical Modelling of Saturated and Unsaturated Groundwater Flow (B H Gilding)Applications of the Homogenization Method to Flow and Transport in Porous Media (U Hornung)Finite-Element-Approximation of Solute Transport in Porous Media with General Adsorption Processes (P Knabner)Free Boundary Problems in Fresh-Salt Goundwater Flow (C J van Duijn) Readership: Applied mathematicians and engineers. Keywords:Porous Media Equation;Diffusion Equation;Transport Equation;Infiltration Equation;Partial Differential Equation(PDE);Degenerate Parabolic Equation;Nonlinear PDE;Multiphase Flow in Porous Media;Nonlinear Diffusion;Reactive Solutes;Adsorption;Fresh and Salt Groundwater Flow;Homogenisation;Nonlinear Partial Differential Equations
Averaged Description of Flow (Steady and Transient) and Nonreactive Solute Transport in Random Porous Media
Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
In previous papers (Shvidler and Karasaki, 1999, 2001, 2005, and 2008) we presented and analyzed an approach for finding the general forms of exactly averaged equations of flow and transport in porous media. We studied systems of basic equations for steady flow with sources in unbounded domains with stochastically homogeneous conductivity fields. A brief analysis of exactly averaged equations of nonsteady flow and nonreactive solute transport was also presented. At the core of this approach is the existence of appropriate random Green's functions. For example, we showed that in the case of a 3-dimensional unbounded domain the existence of appropriate random Green's functions is sufficient for finding the exact nonlocal averaged equations for flow velocity using the operator with a unique kernel-vector. Examination of random fields with global symmetry (isotropy, transversal isotropy and orthotropy) makes it possible to describe significantly different types of averaged equations with nonlocal unique operators. It is evident that the existence of random Green's functions for physical linear processes is equivalent to assuming the existence of some linear random operators for appropriate stochastic equations. If we restricted ourselves to this assumption only, as we have done in this paper, we can study the processes in any dimensional bounded or unbounded fields and in addition, cases in which the random fields of conductivity and porosity are stochastically nonhomogeneous, nonglobally symmetrical, etc. It is clear that examining more general cases involves significant difficulty and constricts the analysis of structural types for the processes being studied. Nevertheless, we show that we obtain the essential information regarding averaged equations for steady and transient flow, as well as for solute transport.
American Doctoral Dissertations
Author: Publisher:
ISBN:
Category : Dissertation abstracts
Languages : en
Pages : 806
Book Description
Applied mechanics reviews
Author: Advances in Hydrology and Climate Change
Author: Surendra Kumar ChandnihaPublisher: CRC Press
ISBN: 1000573699
Category : Science
Languages : en
Pages : 526
Book Description
Highlighting recent trends that employ innovative management and conservation approaches, this volume provides an informative overview of the issues and challenges in water resources affected by climate change, such as drought, flooding, glacier changes, and overbuilt-up urban areas. Focusing on surface and groundwater related issues, the book presents solutions that include such methods as morphometric assessment, parameter estimation, long-term trend analysis, sustainability indexes, storm water management models, entropy-based measurement of long-term precipitation, and more. The volume focuses on providing a better understanding of climatic uncertainty through hydrometeorological data sets and their application in hydrological modeling. These analyses help to serve as the basis for the design of flood-control and water-usage management policies.
CIM Bulletin
Author: Canadian Institute of Mining and MetallurgyPublisher:
ISBN:
Category : Metallurgy
Languages : en
Pages : 720
Book Description