Fluid Flow, Solute Mixing and Precipitation In Porous Media

Fluid Flow, Solute Mixing and Precipitation In Porous Media PDF Author:
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Languages : en
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Fluid Flow, Solute Mixing and Precipitation In Porous Media

Fluid Flow, Solute Mixing and Precipitation In Porous Media PDF Author:
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Category :
Languages : en
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FLUID FLOW, SOLUTE MIXING AND PRECIPITATION IN POROUS MEDIA.

FLUID FLOW, SOLUTE MIXING AND PRECIPITATION IN POROUS MEDIA. PDF Author: George D. Redden
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Category :
Languages : en
Pages :

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Reactions that lead to the formation of mineral precipitates, colloids or growth of biofilms in porous media often depend on the molecular-level diffusive mixing. For example, for the formation of mineral phases, exceeding the saturation index for a mineral is a minimum requirement for precipitation to proceed. Solute mixing frequently occurs at the interface between two solutions each containing one or more soluble reactants, particularly in engineered systems where contaminant degradation or modification or fluid flow are objectives. Although many of the fundamental component processes involved in the deposition or solubilization of solid phases are reasonably well understood, including precipitation equilibrium and kinetics, fluid flow and solute transport, the deposition of chemical precipitates, biofilms and colloidal particles are all coupled to flow, and the science of such coupled processes is not well developed. How such precipitates (and conversely, dissolution of solids) are distributed in the subsurface along flow paths with chemical gradients is a complex and challenging problem. This is especially true in systems that undergo rapid change where equilibrium conditions cannot be assumed, particularly in subsurface systems where reactants are introduced rapidly, compared to most natural flow conditions, and where mixing fronts are generated. Although the concept of dispersion in porous media is frequently used to approximate mixing at macroscopic scales, dispersion does not necessarily describe pore-level or molecular level mixing that must occur for chemical and biological reactions to be possible. An example of coupling between flow, mixing and mineral precipitation, with practical applications to controlling fluid flow or contaminant remediation in subsurface environments is shown in the mixing zone between parallel flowing solutions. Two- and three-dimensional experiments in packed-sand media were conducted where solutions containing calcium and carbonate ions came into contact along a parallel flow boundary and mixed by dispersion and diffusion. The result is the propagation of calcium carbonate precipitates along the solution-solution boundary in the direction of flow. As carbonate precipitates fill the pore space mixing of the two solutions is restricted and therefore precipitation, flow, and transport are coupled. The distribution of carbonate phases is a complex interaction involving precipitation and dissolution kinetics, which are functions of pore-scale saturation indices and solute ratios, heterogeneous vs. homogeneous nucleation and growth mechanisms and changes in porosity and flow. Experimental and modeling results illustrate challenges in understanding the macroscopic and microscopic phenomena that depend on solute mixing, the relevance of molecular and pore-scale processes to the macroscopic behavior, and potential impact on metal mobility in porous media. Mineral precipitation and changes in porosity are simulated at the pore-scale using the Smooth Particle Hydrodynamics method. Macroscopic simulations were performed using discretized, continuum-scale modeling with parameterization representing macroscopic media properties. One of the modeling goals is to use pore-scale simulations to provide the basis for parameterization of macroscopic (more practical) model predictions.

Flow and Transformations in Porous Media

Flow and Transformations in Porous Media PDF Author: Renaud Toussaint
Publisher: Frontiers Media SA
ISBN: 2889450775
Category :
Languages : en
Pages : 202

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Fluid flow in transforming porous rocks, fracture networks, and granular media is a very active interdisciplinary research subject in Physics, Earth Sciences, and Engineering. Examples of natural and engineered processes include hydrocarbon recovery, carbon dioxide geo-sequestration, soil drying and wetting, pollution remediation, soil liquefaction, landslides, dynamics of wet or dry granular media, dynamics of faulting or friction, volcanic eruptions, gas venting in sediments, karst development and speleogenesis, ore deposit development, and radioactive waste disposal. Hydrodynamic flow instabilities and pore scale disorder typically result in complex flow patterning. In transforming media, additional mechanisms come into play: compaction, de-compaction, erosion, segregation, and fracturing lead to changes in permeability over time. Dissolution, precipitation, and chemical reactions between solutes and solids may gradually alter the composition and structure of the solid matrix, either creating or destroying permeable paths for fluid flow. A complex, dynamic feedback thus arises where, on the one hand, the fluid flow affects the characteristics of the porous medium, and on the other hand the changing medium influences the fluid flow. This Research Topic Ebook presents current research illustrating the depth and breadth of ongoing work in the field of flow and transformation in porous media through 15 papers by 72 authors from around the world. The body of work highlights the challenges posed by the vast range of length- and time-scales over which subsurface flow processes occur. Importantly, phenomena from each scale contribute to the larger-scale behavior. The flow of oil and gas in reservoirs, and the flow of groundwater on catchment scale is sensitively linked to pore scale processes and material heterogeneity down to the micrometer scale. The geological features of the same reservoirs and catchments evolved over millions of years, sometimes as a consequence of cracking and fracture growth occurring on the time scale of microseconds. The research presented by the authors of this Research Topic represents a step toward bridging the separation of scales as well as the separation of scientific disciplines so that a more unified picture of flow and transformation in porous media can start to emerge.

Coupled Processes of Fluid Flow, Solute Transport, and Geochemical Reactions in Reactive Barriers

Coupled Processes of Fluid Flow, Solute Transport, and Geochemical Reactions in Reactive Barriers PDF Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 5

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A complex pattern of coupling between fluid flow and mass transport develops when heterogeneous reactions occur. For instance, dissolution and precipitation reactions can change a porous medium's physical properties, such as pore geometry and thus permeability. These changes influence fluid flow, which in turn impacts the composition of dissolved constituents and the solid phases, and the rate and direction of advective transport. Two-dimensional modeling studies using TOUGHREACT were conducted to investigate the coupling between flow and transport developed as a consequence of differences in density, dissolution precipitation, and medium heterogeneity. The model includes equilibrium reactions for aqueous species, kinetic reactions between the solid phases and aqueous constituents, and full coupling of porosity and permeability changes resulting from precipitation and dissolution reactions in porous media. In addition, a new permeability relationship is implemented in TOUGHREACT to examine the effects of geochemical reactions and density difference on plume migration in porous media. Generally, the evolutions in the concentrations of the aqueous phase are intimately related to the reaction-front dynamics. Plugging of the medium contributed to significant transients in patterns of flow and mass transport.

Overland Flow Dynamics and Solute Transport

Overland Flow Dynamics and Solute Transport PDF Author: Vyacheslav G. Rumynin
Publisher: Springer
ISBN: 3319218018
Category : Science
Languages : en
Pages : 296

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Book Description
This book provides essential background knowledge on a wide range of hydrological processes governing contaminant transport from soil to surface water across a range of scales, from hillslope to watershed. The mathematical description of these processes is based on both well-known and unique analytical solutions of different initial and boundary problems (primarily using methods from the kinematic wave theory and the reservoir/lumped-parameter concept), supported by numerical modelling studies. Some research topics, in particular several case studies, are illustrated by monitoring and experimental data analysis to show the importance of the research’s applications in environmental practice and environmental education. Specific results concern the recognition of: (a) the effect of transient rainfall–runoff–infiltration partitioning on the chemical response of drainage areas to excess precipitation under certain field conditions related to the soil, hillslope characteristics, and contaminant properties; (b) soil erosion as a key factor that enhances the potential of adsorbed chemical transport in runoff; and (c) common tendencies in radionuclide behaviour in the near-surface environment contaminated by radioactive fallout from the Chernobyl (1986), Fukushima (2011) and the less known Kyshtym (1957) accidents, as well as from nuclear weapon tests in the atmosphere since 1952. The book’s goal is to provide a conceptual foundation enabling readers to apply scientific knowledge to solve practical problems in environmental hydrology and radiology. More specifically, the book presents the state-of-the-art approaches that scientists and natural resources experts need in order to significantly improve the prediction of changes in the soil–water system chemistry due to human activities.

Porous Fluids

Porous Fluids PDF Author: Vallampati Ramachandra Prasad
Publisher: BoD – Books on Demand
ISBN: 1839627115
Category : Science
Languages : en
Pages : 134

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Book Description
Written by authoritative experts in the field, this book discusses fluid flow and transport phenomena in porous media. Portions of the book are devoted to interpretations of experimental results in this area and directions for future research. It is a useful reference for applied mathematicians and engineers, especially those working in the area of porous media.

Hydrogeophysics

Hydrogeophysics PDF Author: Yorum Rubin
Publisher: Springer Science & Business Media
ISBN: 1402031025
Category : Science
Languages : en
Pages : 518

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Book Description
This ground-breaking work is the first to cover the fundamentals of hydrogeophysics from both the hydrogeological and geophysical perspectives. Authored by leading experts and expert groups, the book starts out by explaining the fundamentals of hydrological characterization, with focus on hydrological data acquisition and measurement analysis as well as geostatistical approaches. The fundamentals of geophysical characterization are then at length, including the geophysical techniques that are often used for hydrogeological characterization. Unlike other books, the geophysical methods and petrophysical discussions presented here emphasize the theory, assumptions, approaches, and interpretations that are particularly important for hydrogeological applications. A series of hydrogeophysical case studies illustrate hydrogeophysical approaches for mapping hydrological units, estimation of hydrogeological parameters, and monitoring of hydrogeological processes. Finally, the book concludes with hydrogeophysical frontiers, i.e. on emerging technologies and stochastic hydrogeophysical inversion approaches.

Pore Scale Geochemical Processes

Pore Scale Geochemical Processes PDF Author: Carl Steefel
Publisher: Walter de Gruyter GmbH & Co KG
ISBN: 1501502077
Category : Science
Languages : en
Pages : 496

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Book Description
This RiMG (Reviews in Mineralogy & Geochemistry) volume includes contributions that review experimental, characterization, and modeling advances in our understanding of pore-scale geochemical processes. The volume had its origins in a special theme session at the 2015 Goldschmidt Conference in Prague. From a diversity of pore-scale topics that ranged from multi-scale characterization to modeling, this work summarizes the state-of-the-science in this subject. Topics include: modification of thermodynamics and kinetics in small pores. chemo-mechanical processes and how they affect porosity evolution in geological media. small angle neutron scattering (SANS) techniques. how isotopic gradients across fluid–mineral boundaries can develop and how these provide insight into pore-scale processes. Information on an important class of models referred to as "pore network" and much more. The material in this book is accessible for graduate students, researchers, and professionals in the earth, material, environmental, hydrological, and biological sciences. The pore scale is readily recognizable to geochemists, and yet in the past it has not received a great deal of attention as a distinct scale or environment that is associated with its own set of questions and challenges. Is the pore scale merely an environment in which smaller scale (molecular) processes aggregate, or are there emergent phenomena unique to this scale? Is it simply a finer-grained version of the "continuum" scale that is addressed in larger-scale models and interpretations? The scale is important because it accounts for the pore architecture within which such diverse processes as multi-mineral reaction networks, microbial community interaction, and transport play out, giving rise to new geochemical behavior that might not be understood or predicted by considering smaller or larger scales alone.

Simulation of Solute Transport Invariably Saturated Porous Media with Supplemental Information on Modifications to the U.S. Geological Survey's Computer Program VS2D

Simulation of Solute Transport Invariably Saturated Porous Media with Supplemental Information on Modifications to the U.S. Geological Survey's Computer Program VS2D PDF Author: R. W. Healy
Publisher:
ISBN:
Category : Diffusion in hydrology
Languages : en
Pages : 136

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Analyses of High Velocity Fluid Flow and Solute Transport in Heterogenous Porous Media

Analyses of High Velocity Fluid Flow and Solute Transport in Heterogenous Porous Media PDF Author: Vladimir D. Cvetković
Publisher:
ISBN:
Category :
Languages : en
Pages : 155

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