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Pore Scale And Continuum Simulations Of Solute Transport Micromodel Benchmark Experiments
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Book Synopsis Pore-scale and Continuum Simulations of Solute Transport Micromodel Benchmark Experiments by :
Download or read book Pore-scale and Continuum Simulations of Solute Transport Micromodel Benchmark Experiments written by and published by . This book was released on 2014 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: Four sets of nonreactive solute transport experiments were conducted with micromodels. Three experiments with one variable, i.e., flow velocity, grain diameter, pore-aspect ratio, and flow-focusing heterogeneity were in each set. The data sets were offered to pore-scale modeling groups to test their numerical simulators. Each set consisted of two learning experiments, for which our results were made available, and one challenge experiment, for which only the experimental description and base input parameters were provided. The experimental results showed a nonlinear dependence of the transverse dispersion coefficient on the Peclet number, a negligible effect of the pore-aspect ratio on transverse mixing, and considerably enhanced mixing due to flow focusing. Five pore-scale models and one continuum-scale model were used to simulate the experiments. Of the pore-scale models, two used a pore-network (PN) method, two others are based on a lattice Boltzmann (LB) approach, and one used a computational fluid dynamics (CFD) technique. Furthermore, we used the learning experiments, by the PN models, to modify the standard perfect mixing approach in pore bodies into approaches to simulate the observed incomplete mixing. The LB and CFD models used the learning experiments to appropriately discretize the spatial grid representations. For the continuum modeling, the required dispersivity input values were estimated based on published nonlinear relations between transverse dispersion coefficients and Peclet number. Comparisons between experimental and numerical results for the four challenge experiments show that all pore-scale models were all able to satisfactorily simulate the experiments. The continuum model underestimated the required dispersivity values, resulting in reduced dispersion. The PN models were able to complete the simulations in a few minutes, whereas the direct models, which account for the micromodel geometry and underlying flow and transport physics, needed up to several days on supercomputers to resolve the more complex problems.
Book Synopsis Pore Scale Geochemical Processes by : Carl Steefel
Download or read book Pore Scale Geochemical Processes written by Carl Steefel and published by Walter de Gruyter GmbH & Co KG. This book was released on 2015-09-25 with total page 496 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Modeling Single-phase Flow and Solute Transport Across Scales by : Yashar Mehmani
Download or read book Modeling Single-phase Flow and Solute Transport Across Scales written by Yashar Mehmani and published by . This book was released on 2014 with total page 586 pages. Available in PDF, EPUB and Kindle. Book excerpt: Flow and transport phenomena in the subsurface often span a wide range of length (nanometers to kilometers) and time (nanoseconds to years) scales, and frequently arise in applications of CO2 sequestration, pollutant transport, and near-well acid stimulation. Reliable field-scale predictions depend on our predictive capacity at each individual scale as well as our ability to accurately propagate information across scales. Pore-scale modeling (coupled with experiments) has assumed an important role in improving our fundamental understanding at the small scale, and is frequently used to inform/guide modeling efforts at larger scales. Among the various methods, there often exists a trade-off between computational efficiency/simplicity and accuracy. While high-resolution methods are very accurate, they are computationally limited to relatively small domains. Since macroscopic properties of a porous medium are statistically representative only when sample sizes are sufficiently large, simple and efficient pore-scale methods are more attractive. In this work, two Eulerian pore-network models for simulating single-phase flow and solute transport are developed. The models focus on capturing two key pore-level mechanisms: a) partial mixing within pores (large void volumes), and b) shear dispersion within throats (narrow constrictions connecting the pores), which are shown to have a substantial impact on transverse and longitudinal dispersion coefficients at the macro scale. The models are verified with high-resolution pore-scale methods and validated against micromodel experiments as well as experimental data from the literature. Studies regarding the significance of different pore-level mixing assumptions (perfect mixing vs. partial mixing) in disordered media, as well as the predictive capacity of network modeling as a whole for ordered media are conducted. A mortar domain decomposition framework is additionally developed, under which efficient and accurate simulations on even larger and highly heterogeneous pore-scale domains are feasible. The mortar methods are verified and parallel scalability is demonstrated. It is shown that they can be used as "hybrid" methods for coupling localized pore-scale inclusions to a surrounding continuum (when insufficient scale separation exists). The framework further permits multi-model simulations within the same computational domain. An application of the methods studying "emergent" behavior during calcite precipitation in the context of geologic CO2 sequestration is provided.
Book Synopsis Analysis of Solute Mixing at the Pore-scale Using Micromodels and Lattice-Boltzmann Finite Volume Modeling by : Thomas W. Willingham
Download or read book Analysis of Solute Mixing at the Pore-scale Using Micromodels and Lattice-Boltzmann Finite Volume Modeling written by Thomas W. Willingham and published by . This book was released on 2006 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt: Transverse mixing has been shown to often be the controlling mechanisms for degradation of contaminants in groundwater. For a conservative contaminant, downgradient concentrations depend on initial source zone concentrations and the extent to which the contaminant mixes (i.e., dilutes) with surrounding groundwater. For a (bio)reactive contaminant, downgradient concentrations also depend on the rate of reaction. In this work I examine the effects of porous media structure (geometry) on the extent of a bi-molecular reaction utilizing a combination of pore scale modeling and high-resolution 2D micromodels. To evaluate reactive transport, two reactive substrates are introduced into a network of pores via two separate and parallel fluid streams. The substrates mix within the porous media via transverse dispersion and react. In micromodel experiments, the reaction forms a fluorescent product which is quantified utilizing fluorescent microscopy. Experimental micromodel results are compared directly with simulations from a pore scale lattice-Boltzmann (LB) finite volume model (FVM) utilizing identical pore structures and flow rates. The LB method is used to solve for interstitial pore velocities. Reactive transport is simulated by combining pore velocities from the LB model with a reactive transport FVM model. Pore scale modeling and experimental results are up-scaled to determine transverse dispersion coefficients at the continuum scale. Results from pore scale simulations and micromodel experiments indicate that (i) LB-FVM is able to capture the mechanisms controlling mixing-limited reactive transport in 2D micromodel experiments, (ii) flow focusing in high conductivity preferential flow zones enhances reactive transport, (iii) grain orientation has a significant effect on extent of mixing and product formation, (iv) grain size (as is commonly used) is not an accurate predictor of mixing, and (v) intra-particle porosity does not have a significant effect on steady-state pore-scale transverse mixing. Finally, excellent agreement between reactive micromodel experiments and forward modeled continuum predictions of reactive transport determined from up-scaled conservative micromodel experimental results was found. This study suggests that sub-continuum effects such as grain orientation, flow focusing, and effective interfacial plume area can play an important role in overall extent of mixing and reaction in groundwater flow, and hence may need to be considered when evaluating reactive transport at the continuum scale.
Book Synopsis Pore-scale Microstructure, Mechanisms, and Models for Subsurface Flow and Transport by : James E. McClure
Download or read book Pore-scale Microstructure, Mechanisms, and Models for Subsurface Flow and Transport written by James E. McClure and published by Frontiers Media SA. This book was released on 2022-11-29 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Glassy Materials Based Microdevices by : Giancarlo C. Righini
Download or read book Glassy Materials Based Microdevices written by Giancarlo C. Righini and published by MDPI. This book was released on 2019-02-28 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt: Microtechnology has changed our world since the last century, when silicon microelectronics revolutionized sensor, control and communication areas, with applications extending from domotics to automotive, and from security to biomedicine. The present century, however, is also seeing an accelerating pace of innovation in glassy materials; as an example, glass-ceramics, which successfully combine the properties of an amorphous matrix with those of micro- or nano-crystals, offer a very high flexibility of design to chemists, physicists and engineers, who can conceive and implement advanced microdevices. In a very similar way, the synthesis of glassy polymers in a very wide range of chemical structures offers unprecedented potential of applications. The contemporary availability of microfabrication technologies, such as direct laser writing or 3D printing, which add to the most common processes (deposition, lithography and etching), facilitates the development of novel or advanced microdevices based on glassy materials. Biochemical and biomedical sensors, especially with the lab-on-a-chip target, are one of the most evident proofs of the success of this material platform. Other applications have also emerged in environment, food, and chemical industries. The present Special Issue of Micromachines aims at reviewing the current state-of-the-art and presenting perspectives of further development. Contributions related to the technologies, glassy materials, design and fabrication processes, characterization, and, eventually, applications are welcome.
Book Synopsis Intercomparison of 3D Pore-scale Flow and Solute Transport Simulation Methods by :
Download or read book Intercomparison of 3D Pore-scale Flow and Solute Transport Simulation Methods written by and published by . This book was released on 2015 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this study, multiple numerical approaches have been developed to simulate porous media fluid flow and solute transport at the pore scale. These include (1) methods that explicitly model the three-dimensional geometry of pore spaces and (2) methods that conceptualize the pore space as a topologically consistent set of stylized pore bodies and pore throats. In previous work we validated a model of the first type, using computational fluid dynamics (CFD) codes employing a standard finite volume method (FVM), against magnetic resonance velocimetry (MRV) measurements of pore-scale velocities. Here we expand that validation to include additional models of the first type based on the lattice Boltzmann method (LBM) and smoothed particle hydrodynamics (SPH), as well as a model of the second type, a pore-network model (PNM). The PNM approach used in the current study was recently improved and demonstrated to accurately simulate solute transport in a two-dimensional experiment. While the PNM approach is computationally much less demanding than direct numerical simulation methods, the effect of conceptualizing complex three-dimensional pore geometries on solute transport in the manner of PNMs has not been fully determined. We apply all four approaches (FVM-based CFD, LBM, SPH and PNM) to simulate pore-scale velocity distributions and (for capable codes) nonreactive solute transport, and intercompare the model results. Comparisons are drawn both in terms of macroscopic variables (e.g., permeability, solute breakthrough curves) and microscopic variables (e.g., local velocities and concentrations). Generally good agreement was achieved among the various approaches, but some differences were observed depending on the model context. The intercomparison work was challenging because of variable capabilities of the codes, and inspired some code enhancements to allow consistent comparison of flow and transport simulations across the full suite of methods. This study provides support for confidence in a variety of pore-scale modeling methods and motivates further development and application of pore-scale simulation methods.
Book Synopsis Pore Scale Simulation of Transport in Porous Media by :
Download or read book Pore Scale Simulation of Transport in Porous Media written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: When performing solute transport in porous media one often observes an asymmetric break-through curve with a very slow decline of the concentration. This phenomenon even appears with non-sorbing solutes and is known as tailing. There are several hypotheses to explain this phenomenon. The modelling is often done using the mobile-immobile model (MIM), which assumes that parts of the solvent are not moving along with the general flow. The solutes can move into these stagnant zones by diffusion which leads to the observed tailing. In this thesis it is checked whether tailing can indeed be explained by stagnant zones, which may result e.g. from dead-end pores or pores perpendicular to the direction of the flow. A program to simulate transport in porous media was developed and verified using several test-problems. An example calculation with a randomly generated porous medium was performed. The resulting break-through curves showed significant tailing.
Book Synopsis Characterizing and Upscaling Transport, Mixing and Reactions in Porous Media by : David Lee Hochstetler
Download or read book Characterizing and Upscaling Transport, Mixing and Reactions in Porous Media written by David Lee Hochstetler and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Reactive transport in porous media is critical to many subsurface environmental issues including the fate and transport of contaminants, nuclear waste disposal, and carbon dioxide sequestration. Often, dilution and mixing are the controlling factors in each of these processes, such as the overlapping of plumes containing different reactants that is necessary for (bio)degradation of a groundwater contaminant. Thus, improved quantification of mixing, including upscaling relationships, parameterizations, and metrics for dilution and reactive mixing, are necessary for enhanced understanding, predictive modeling, and management of resources. There is a crucial need to improve the upscaling of parameters from the pore-scale to the Darcy and field scale, as well as improve our understanding of the phenomena that manifest at the macroscale as a result of the interaction of coupled physical and (bio)chemical processes at the pore scale. In this dissertation, pore-scale numerical models are used in combination with continuum models and lab (bench) scale experiments in order to study the coupled processes of flow, mixing, and reactions in three different studies. Also, a theoretical derivation is provided for the transport of the entropy of a reactive species, and several applications are used to illustrate its potential as a metric for reactive mixing and dilution. In the first study, pore-scale models are used to explore the unresolved question of the impact of using effective versus intrinsic reaction rate constants for predicting reactive transport in porous media. For a case of displacement and mixing of two solutions with irreversible bimolecular reactions, breakthrough curves from multiple locations are analyzed for conservative and reactive transport, as well as the segregation of reactant species along the cross-sections. For a range of Damköhler numbers (Da), effective reaction rate parameters are found and an empirical formula is developed to describe the relationship between the reaction effectiveness factor and $Da$. This helps describe the upscaled system behavior. The pore-scale results confirm the segregation concept advanced by Kapoor et al. (1997); however, for Da> 1, the effective rate constant is much less than the intrinsic rate constant, yet the relative difference in total mass transformation between the pore-scale simulation and what is predicted by the upscaled continuum model using the intrinsic rate constant is rather modest, of the order of about 10%. The explanation for this paradox is the early transition from a rate-limited to a mixing-limited regime, which results in a model that is relatively insensitive to the rate constant because mixing controls the availability of reactants. Thus, the reaction-rate parameter used in the model has limited influence on the rate of product computed. The second and third studies focus on transverse mixing, which often is critical for reactions to occur in porous media. In the second study, multitracer laboratory bench-scale experiments and pore-scale simulations are used to (i) determine a generalized parameterization of transverse hydrodynamic dispersion at the continuum Darcy scale, (ii) improve understanding of basic transport processes at the subcontinuum scale and how they manifest macroscopically, and (iii) quantify the importance of aqueous diffusion for transport of different solutes. In order to capture the observed results from the pore-scale and lab-scale, a nonlinear compound specific parameterization of transverse dispersion is necessary. The pore-scale simulations illustrate that the interplay between advective and diffusive mass transfer results in transverse concentration gradients leading to incomplete mixing in the pore channels. Ultimately, this affects local transverse mixing at the Darcy scale even at high flow velocities. In the third study, different pseudorandom pore-scale porous media are used for both conservative and reactive simulations, and the impact of the choice of transverse dispersion parameterization on predicting mixing-limited reactive transport with a continuum formulation is explored. Again, both pore-scale numerical simulations and flow-through laboratory experiments are used. The nonlinear parameterization of transverse dispersion consistently predicts both product mass flux and reactant plume extents across two orders of magnitude of mean flow velocities. In contrast, the classical linear parameterization of transverse dispersion, assuming a constant dispersivity as a property of the porous medium, could not consistently predict either indicator with great accuracy. Furthermore, the linear parameterization of transverse dispersion predicts an asymptotic (constant) plume length with increasing velocity while the nonlinear parameterization indicates that the plume length increases with the square root of the velocity. Both the pore-scale model simulations and the laboratory experiments of mixing-limited reactive transport show the latter relationship. A final issue this thesis addresses is the need for appropriate metrics that accurately quantify the interplay between mixing and reactive processes. The exponential of the Shannon entropy of the concentration probability distribution has been proposed and applied to quantify the dilution of conservative solutes either in a given volume or in a given water flux via the dilution index and the flux-related dilution index, respectively. In the final study, the transport equation for the entropy of a reactive solute is derived. Using a flux-related framework, it is shown that the degree of uniformity of the solute mass flux distribution for a reactive species and its rate of change are informative measures of physical and (bio)chemical processes and their complex interaction.
Book Synopsis Transverse Dispersion in Liquid Flow Through Porous Media by : Eugene Sidney Simpson
Download or read book Transverse Dispersion in Liquid Flow Through Porous Media written by Eugene Sidney Simpson and published by . This book was released on 1962 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Experimental and Theoretical Analysis of Closed-flow Column Experiments by : Thomas Ritschel
Download or read book Experimental and Theoretical Analysis of Closed-flow Column Experiments written by Thomas Ritschel and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Research of solute transport fundamentally contributes to our understanding of soil functions as most processes in soils are dynamically driven and related to the transient conditions produced by the transport of solutes. For this reason, especially the transport of contaminants is frequently studied with laboratory scale column outflow experiments in an open-flow mode. This thesis presents a complementary approach of conducting saturated column experiments that is characterized by the recirculation of the effluent into the inflow via a mixing vessel and is therefore referred to as closed-flow mode column experiment. Depending on the ratio of the volume of the mixing vessel and the water-filled pore space, a damped oscillating concentration emerges in the effluent and in the mixing vessel. Oscillation frequency, damping and amplitude are thereby governed by the properties of the porous medium and the target substance. It was shown by column experiments with quartz sand that the appearance of oscillations can be controlled by using different mixing vessel solute volumes. The breakthrough data obtained within these experiments was then used to validate a numerical model that was derived by coupling the numerical solution of a transport equation with the model describing the mixing vessel in a loop. This model was used for a comprehensive sensitivity analysis to illustrate the response of the breakthrough curve to changes in the dispersion and the parameters describing adsorption with respect to strength, rate and nonlinearity. Each process thereby produced unique responses that confirm the high information content of closed-flow breakthrough data, which has shown to intrinsically contain information on the water content and the pumping rate as well. Finally, a numerical analysis of inverse parameter determination revealed a massive decrease in parameter uncertainty under optimal conditions, which renders the approach also highly relevant for practical applications.
Book Synopsis Upscaling and Multiscale Simulation by Bridging Pore Scale and Continuum Scale Models by : Tie Sun (Ph. D.)
Download or read book Upscaling and Multiscale Simulation by Bridging Pore Scale and Continuum Scale Models written by Tie Sun (Ph. D.) and published by . This book was released on 2012 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many engineering and scientific applications of flow in porous media are characterized by transport phenomena at multiple spatial scales, including pollutant transport, groundwater remediation, and acid injection to enhance well production. Carbon sequestration in particular is a multiscale problem, because the trapping and leakage mechanisms of CO2 in the subsurface occur from the sub-pore level to the basin scale. Quantitative and predictive pore-scale modeling has long shown to be a valuable tool for studying fluid-rock interactions in porous media. However, due to the size limitation of the pore-scale models (10−4-10−2m), it is impossible to model an entire reservoir at the pore scale. A straightforward multiscale approach would be to upscale macroscopic parameters (e.g. permeability) directly from pore-scale models and then input them into a continuum-scale simulator. However, it has been found that the large-scale models do not predict in many cases. One possible reason for the inaccuracies is oversimplified boundary conditions used in this direct upscaling approach. The hypothesis of this work is that pore-level flow and upscaled macroscopic parameters depends on surrounding flow behavior manifested in the form of boundary conditions. The detailed heterogeneity captured by the pore-scale models may be partially lost if oversimplified boundary conditions are employed in a direct upscaling approach. As a result, extracted macroscopic properties may be inaccurate. Coupling the model to surrounding media (using finite element mortars to ensure continuity between subdomains) would result in more realistic boundary conditions, and can thus improve the accuracy of the upscaled parameters. To test the hypothesis, mortar coupling is employed to couple pore-scale models and also couple pore-scale models to continuum models. Flow field derived from mortar coupling and direct upscaling are compared, preferably against a true solution if one exists. It is found in this dissertation that pore-scale flow and upscaled parameters can be significantly affected by the surrounding media. Therefore, using arbitrary boundary conditions such as constant pressure and no-flow boundaries may yield misleading results. Mortar coupling captures the detailed variation on the interface and imposes realistic boundary conditions, thus estimating more accurate upscaled values and flow fields. An advanced upscaling tool, a Super Permeability Tensor (SPT) is developed that contains pore-scale heterogeneity in greater detail than a conventional permeability tensor. Furthermore, a multiscale simulator is developed taking advantage of mortar coupling to substitute continuum grids directly with pore-scale models where needed. The findings from this dissertation can significantly benefit the understanding of fluid flow in porous media, and, in particular, CO2 storage in geological formations which requires accurate modeling across multiple scales. The fine-scale models are sensitive to the boundary conditions, and the large scale modeling of CO2 transport is sensitive to the CO2 behavior affected by the pore-scale heterogeneity. Using direct upscaling might cause significant errors in both the fine-scale and the large-scale model. The multiscale simulator developed in this dissertation could integrate modeling of CO2 physics at all relevant scales, which span the sub-pore or pore level to the basin scale, into one single simulator with effective and accurate communication between the scales. The multiscale simulator provides realistic boundary conditions for the fine scales, accurate upscaled information to continuum-scale, and allows for the distribution of computational power where needed, thus maintaining high accuracy with relatively low computational cost.
Book Synopsis Simulation of Flow and Transport at the Micro (Pore) Scale by :
Download or read book Simulation of Flow and Transport at the Micro (Pore) Scale written by and published by . This book was released on 2007 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: An important problem in porous media involves the ability of micron and submicron-sized biological particles such as viruses or bacteria to move in groundwater systems through geologic media characterized by rock or mixed gravel, clay and sand materials. Current simulation capabilities require properly upscaled (continuum) models of colloidal filtration and adsorption to augment existing theories of fluid flow and chemical transport. Practical models typically address flow and transport behavior in aquifers over distances of 1 to 10 km where, for example, fluid momentum balance is governed by the simple Darcy's Law as a function of a pressure gradient, elevation gradient and a medium-dependent permeability parameter. In addition to fluid advection, there are multiple transport processes occurring in these systems including diffusion, dispersion and chemical interactions with solids or other aqueous chemical species. Particle transport is typically modeled in the same way as dissolved species, except that additional loss terms are incorporated to model particle filtration (physical interception), adsorption (chemical interception) and inactivation. Proper resolution of these processes at the porous medium continuum scale constitutes an important closure problem in subsurface science. We present a new simulation capability based on enabling technologies developed for microfluidics applications to model transport of colloidal-sized particles at the microscale, with relevance to the pore scale in geophysical subsurface systems. Particulate is represented by a bead-rod polymer model and is fully-coupled to a Newtonian solvent described by Navier-Stokes. Finite differences are used to discretize the interior of the domain; a Cartesian grid embedded boundary/volume-of-fluid method is used near boundaries and interfaces. This approach to complex geometry is amenable to direct simulation on grids obtained from surface extractions of tomographic image data. Short-range interactions are included in the particle model. This capability has been previously demonstrated on polymer flow in spatially-resolved packed bed (3D) and post array (2D) systems. We also discuss the advantages of this approach for the development of high-resolution adaptive algorithms for multiscale continuum-particle and mesoscale coarse-grained molecular dynamics models.
Book Synopsis Pore Scale Simulation of Transport in Porous Media by : Jorrit Fahlke
Download or read book Pore Scale Simulation of Transport in Porous Media written by Jorrit Fahlke and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis On Some Problems in the Simulation of Flow and Transport Through Porous Media by : Sunil George Thomas
Download or read book On Some Problems in the Simulation of Flow and Transport Through Porous Media written by Sunil George Thomas and published by . This book was released on 2009 with total page 450 pages. Available in PDF, EPUB and Kindle. Book excerpt: The dynamic solution of multiphase flow through porous media is of special interest to several fields of science and engineering, such as petroleum, geology and geophysics, bio-medical, civil and environmental, chemical engineering and many other disciplines. A natural application is the modeling of the flow of two immiscible fluids (phases) in a reservoir. Others, that are broadly based and considered in this work include the hydrodynamic dispersion (as in reactive transport) of a solute or tracer chemical through a fluid phase. Reservoir properties like permeability and porosity greatly influence the flow of these phases. Often, these vary across several orders of magnitude and can be discontinuous functions. Furthermore, they are generally not known to a desired level of accuracy or detail and special inverse problems need to be solved in order to obtain their estimates. Based on the physics dominating a given sub-region of the porous medium, numerical solutions to such flow problems may require different discretization schemes or different governing equations in adjacent regions. The need to couple solutions to such schemes gives rise to challenging domain decomposition problems. Finally, on an application level, present day environment concerns have resulted in a widespread increase in CO2 capture and storage experiments across the globe. This presents a huge modeling challenge for the future. This research work is divided into sections that aim to study various inter-connected problems that are of significance in sub-surface porous media applications. The first section studies an application of mortar (as well as nonmortar, i.e., enhanced velocity) mixed finite element methods (MMFEM and EV-MFEM) to problems in porous media flow. The mortar spaces are first used to develop a multiscale approach for parabolic problems in porous media applications. The implementation of the mortar mixed method is presented for two-phase immiscible flow and some a priori error estimates are then derived for the case of slightly compressible single-phase Darcy flow. Following this, the problem of modeling flow coupled to reactive transport is studied. Applications of such problems include modeling bio-remediation of oil spills and other subsurface hazardous wastes, angiogenesis in the transition of tumors from a dormant to a malignant state, contaminant transport in groundwater flow and acid injection around well bores to increase the permeability of the surrounding rock. Several numerical results are presented that demonstrate the efficiency of the method when compared to traditional approaches. The section following this examines (non-mortar) enhanced velocity finite element methods for solving multiphase flow coupled to species transport on non-matching multiblock grids. The results from this section indicate that this is the recommended method of choice for such problems. Next, a mortar finite element method is formulated and implemented that extends the scope of the classical mortar mixed finite element method developed by Arbogast et al (12) for elliptic problems and Girault et al (62) for coupling different numerical discretization schemes. Some significant areas of application include the coupling of pore-scale network models with the classical continuum models for steady single-phase Darcy flow as well as the coupling of different numerical methods such as discontinuous Galerkin and mixed finite element methods in different sub-domains for the case of single phase flow (21, 109). These hold promise for applications where a high level of detail and accuracy is desired in one part of the domain (often associated with very small length scales as in pore-scale network models) and a much lower level of detail at other parts of the domain (at much larger length scales). Examples include modeling of the flow around well bores or through faulted reservoirs. The next section presents a parallel stochastic approximation method (68, 76) applied to inverse modeling and gives several promising results that address the problem of uncertainty associated with the parameters governing multiphase flow partial differential equations. For example, medium properties such as absolute permeability and porosity greatly influence the flow behavior, but are rarely known to even a reasonable level of accuracy and are very often upscaled to large areas or volumes based on seismic measurements at discrete points. The results in this section show that by using a few measurements of the primary unknowns in multiphase flow such as fluid pressures and concentrations as well as well-log data, one can define an objective function of the medium properties to be determined, which is then minimized to determine the properties using (as in this case) a stochastic analog of Newton's method. The last section is devoted to a significant and current application area. It presents a parallel and efficient iteratively coupled implicit pressure, explicit concentration formulation (IMPEC) (52-54) for non-isothermal compositional flow problems. The goal is to perform predictive modeling simulations for CO2 sequestration experiments. While the sections presented in this work cover a broad range of topics they are actually tied to each other and serve to achieve the unifying, ultimate goal of developing a complete and robust reservoir simulator. The major results of this work, particularly in the application of MMFEM and EV-MFEM to multiphysics couplings of multiphase flow and transport as well as in the modeling of EOS non-isothermal compositional flow applied to CO2 sequestration, suggest that multiblock/multimodel methods applied in a robust parallel computational framework is invaluable when attempting to solve problems as described in Chapter 7. As an example, one may consider a closed loop control system for managing oil production or CO2 sequestration experiments in huge formations (the "instrumented oil field"). Most of the computationally costly activity occurs around a few wells. Thus one has to be able to seamlessly connect the above components while running many forward simulations on parallel clusters in a multiblock and multimodel setting where most domains employ an isothermal single-phase flow model except a few around well bores that employ, say, a non-isothermal compositional model. Simultaneously, cheap and efficient stochastic methods as in Chapter 8, may be used to generate history matches of well and/or sensor-measured solution data, to arrive at better estimates of the medium properties on the fly. This is obviously beyond the scope of the current work but represents the over-arching goal of this research.
Book Synopsis Pore-scale Simulation Frameworks for Flow and Transport in Complex Porous Media by : Feng Xiao
Download or read book Pore-scale Simulation Frameworks for Flow and Transport in Complex Porous Media written by Feng Xiao and published by . This book was released on 2013 with total page 125 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Pore-scale Direct Numerical Simulation of Flow and Transport in Porous Media by : Sreejith Pulloor Kuttanikkad
Download or read book Pore-scale Direct Numerical Simulation of Flow and Transport in Porous Media written by Sreejith Pulloor Kuttanikkad and published by . This book was released on 2009 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
