Download or read book Modeling Transport in Fractured Porous Media with the Random Walk Particle Method written by and published by . This book was released on 2001 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: Multiscale features of transport processes in fractured porous media make numerical modeling a difficult task, both in conceptualization and computation. Modeling the mass transfer through the fracture-matrix interface is one of the critical issues in the simulation of transport in a fractured porous medium. Because conventional dual-continuum-based numerical methods are unable to capture the transient features of the diffusion depth into the matrix (unless they assume a passive matrix medium), such methods will overestimate the transport of tracers through the fractures, especially for the cases with large fracture spacing, resulting in artificial early breakthroughs. We have developed a new method for calculating the particle-transfer probability that can capture the transient features of diffusion depth into the matrix within the framework of the dual-continuum random-walk particle method (RWPM) by introducing a new concept of activity range of a particle within the matrix. Unlike the multiple-continuum approach, the new dual-continuum RWPM does not require using additional grid blocks to represent the matrix. It does not assume a passive matrix medium and can be applied to the cases where global water flow exists in both continua. The new method has been verified against analytical solutions for transport in the fracture-matrix systems with various fracture spacing. The calculations of the breakthrough curves of radionuclides from a potential repository to the water table in Yucca Mountain demonstrate the effectiveness of the new method for simulating 3-D, mountain-scale transport in a heterogeneous, fractured porous medium under variably saturated conditions.

Download or read book Flow and Transport in Porous Media and Fractured Rock written by Muhammad Sahimi and published by John Wiley & Sons. This book was released on 2011-05-09 with total page 635 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this standard reference of the field, theoretical and experimental approaches to flow, hydrodynamic dispersion, and miscible displacements in porous media and fractured rock are considered. Two different approaches are discussed and contrasted with each other. The first approach is based on the classical equations of flow and transport, called 'continuum models'. The second approach is based on modern methods of statistical physics of disordered media; that is, on 'discrete models', which have become increasingly popular over the past 15 years. The book is unique in its scope, since (1) there is currently no book that compares the two approaches, and covers all important aspects of porous media problems; and (2) includes discussion of fractured rocks, which so far has been treated as a separate subject. Portions of the book would be suitable for an advanced undergraduate course. The book will be ideal for graduate courses on the subject, and can be used by chemical, petroleum, civil, environmental engineers, and geologists, as well as physicists, applied physicist and allied scientists that deal with various porous media problems.

Download or read book Flow and Transport in Fractured Porous Media written by Peter Dietrich and published by Springer Science & Business Media. This book was released on 2005-12-12 with total page 455 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book addresses the characterization of flow and transport in porous fractured media from experimental and modeling perspectives. It provides a comprehensive presentation of investigations performed and analyzed on different scales.

Download or read book Core and Field Scale Modeling of Miscible Injection Processes in Fractured Porous Media Using Random Walk and Particle Tracking Methods written by Ekaterina Stalgorova and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Flows in Porous Media and Fractured Rock written by Muhammad Sahimi and published by Wiley-VCH. This book was released on 1995-02-22 with total page 504 pages. Available in PDF, EPUB and Kindle. Book excerpt: Provides a comprehensive discussion of porous media problems, experimental methods for characterizing porous structures, classical approaches and modern methods and a comparison of both, and fractured rock and porous media.

Download or read book Development of RWHet to Simulate Contaminant Transport in Fractured Porous Media written by and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Accurate simulation of matrix diffusion in regional-scale dual-porosity and dual-permeability media is a critical issue for the DOE Underground Test Area (UGTA) program, given the prevalence of fractured geologic media on the Nevada National Security Site (NNSS). Contaminant transport through regional-scale fractured media is typically quantified by particle-tracking based Lagrangian solvers through the inclusion of dual-domain mass transfer algorithms that probabilistically determine particle transfer between fractures and unfractured matrix blocks. UGTA applications include a wide variety of fracture aperture and spacing, effective diffusion coefficients ranging four orders of magnitude, and extreme end member retardation values. This report incorporates the current dual-domain mass transfer algorithms into the well-known particle tracking code RWHet [LaBolle, 2006], and then tests and evaluates the updated code. We also develop and test a direct numerical simulation (DNS) approach to replace the classical transfer probability method in characterizing particle dynamics across the fracture/matrix interface. The final goal of this work is to implement the algorithm identified as most efficient and effective into RWHet, so that an accurate and computationally efficient software suite can be built for dual-porosity/dual-permeability applications. RWHet is a mature Lagrangian transport simulator with a substantial user-base that has undergone significant development and model validation. In this report, we also substantially tested the capability of RWHet in simulating passive and reactive tracer transport through regional-scale, heterogeneous media. Four dual-domain mass transfer methodologies were considered in this work. We first developed the empirical transfer probability approach proposed by Liu et al. [2000], and coded it into RWHet. The particle transfer probability from one continuum to the other is proportional to the ratio of the mass entering the other continuum to the mass in the current continuum. Numerical examples show that this method is limited to certain ranges of parameters, due to an intrinsic assumption of an equilibrium concentration profile in the matrix blocks in building the transfer probability. Subsequently, this method fails in describing mass transfer for parameter combinations that violate this assumption, including small diffusion coefficients (i.e., the free-water molecular diffusion coefficient 1×10-11 meter2/second), relatively large fracture spacings (such as meter), and/or relatively large matrix retardation coefficients (i.e.,). These "outliers" in parameter range are common in UGTA applications. To address the above limitations, we then developed a Direct Numerical Simulation (DNS)-Reflective method. The novel DNS-Reflective method can directly track the particle dynamics across the fracture/matrix interface using a random walk, without any empirical assumptions. This advantage should make the DNS-Reflective method feasible for a wide range of parameters. Numerical tests of the DNS-Reflective, however, show that the method is computationally very demanding, since the time step must be very small to resolve particle transfer between fractures and matrix blocks. To improve the computational efficiency of the DNS approach, we then adopted Roubinet et al.'s method [2009], which uses first passage time distributions to simulate dual-domain mass transfer. The DNS-Roubinet method was found to be computationally more efficient than the DNS-Reflective method. It matches the analytical solution for the whole range of major parameters (including diffusion coefficient and fracture aperture values that are considered "outliers" for Liu et al.'s transfer probability method [2000]) for a single fracture system. The DNS-Roubinet method, however, has its own disadvantage: for a parallel fracture system, the truncation of the first passage time distribution creates apparent errors when the fracture spacin ...

Download or read book A Random Walk Particle Tracking Methodology to Model Reactive Transport in Heterogeneous Porous Media written by Adolfo Castro and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Flow and Transport in Complex Porous Media written by Hamza Oukili (docteur en physique).) and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Particle methods have been extensively used for modeling transport problems in porous soils, aquifers, and reservoirs. They reduce or avoid some of the problems of Eulerian methods, e.g. instabilities, excessive artificial diffusion, mass balance, and/or oscillations that could lead to negative concentrations. This thesis develops a new class of gridless Lagrangian particle methods for modeling flow and transport phenomena in complex porous media with heterogeneities and discontinuities. Firstly, stochastic processes are reviewed, in relation to particle positions X(t) and to the corresponding macroscopic Advection-Diffusion Equation (ADE). This review leads to the conditions required for the Probability Density Function (PDF) of X(t) to satisfy the Fokker-Planck equation (and the ADE). However, one of these conditions is the differentiability of transport coefficients: therefore, discontinuities are difficult to treat, particularly discontinuous diffusion D(x) and porosity q(x). In the literature on particle Random Walks, the methods used to handle discontinuous diffusion required excessively small time steps. These restrictions on the time step lead to inefficient algorithms. In this study, we propose a novel approach without restrictions on time step size. The novel RWPT (Random Walk Particle Tracking) algorithms proposed here are discrete in time and continuous in space (gridless). They are based on an adaptive “Stop&Go” time-stepping, combined with partial reflection/refraction schemes, and extended with three new concepts: negative mass particles; adaptive mass particles; and “homing” particles. To test the new Stop&Go RWPT schemes in infinite domains, we develop analytical and semi-analyticalsolutions for diffusion in the presence of multiple interfaces (discontinuous multi-layered medium) in infinite domains. The results show that the proposed Stop&Go RWPT schemes (with adaptive, negative, or homing particles) fit extremely well the semi-analytical solutions, even for very high contrasts for transport properties even in the neighborhood of the interfaces. The schemes provide a correct diffusive solution in only a few macro-steps (macroscopic time steps), with a precision that depends only on the number of particles, and not on the macro-step. The algorithms are then, extended from infinite to semi-infinite and finite domains. Dirichlet conditions are particularly difficult to implement in particle methods. Thus, in this thesis we propose different methods on how to implement Dirichlet boundary conditions with the “discontinuous” RWPT algorithm. This study proposes an algorithm to solve diffusion equations semi-analytically in heterogeneous semi-infinite and finite domains with Dirichlet boundary conditions. The RWPT Dirichlet methods are then checked analytically and verified for various configurations. Finally, the RWPT method is applied for studying diffusion at different scales in 2D composite media (grain/pore systems). A zero-flux condition is assumed locally at the grain/pore interfaces. At the macro-scale, diffusion occurs in an equivalent effective homogeneous medium with macroscopic parameters (porosity and effective diffusion coefficients) obtained from the temporal evolution of second order moments. The RWPT algorithm is then applied to more complex geometries of grains and pores. Different configurations or structures at the micro-scale level will be chosen in order to obtain composite isotropic media at the macro-scale level with different porosities. Then, by choosing elongated micro-structures, anisotropy effects emerge at the macroscopic level. Effective macro-scale properties (porosities, effective diffusion tensors, tortuosities) are calculated using the second order moment. The different methods proposed in this thesis can be used for different problems, since each has its drawbacks and advantages. The schemes proposed seem promising with a view to extensions towards more complex 3D geometries.

Download or read book An Improvement to DCPT written by and published by . This book was released on 2001 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt: Multi-scale features of transport processes in fractured porous media make numerical modeling a difficult task of both conceptualization and computation. Dual-continuum particle tracker (DCPT) is an attractive method for modeling large-scale problems typically encountered in the field, such as those in unsaturated zone (UZ) of Yucca Mountain, Nevada. The major advantage is its capability to capture the major features of flow and transport in fractured porous rock (i-e., a fast fracture sub-system combined with a slow matrix sub-system) with reasonable computational resources. However, like other conventional dual-continuum approach-based numerical methods, DCPT (v1.0) is often criticized for failing to capture the transient features of the diffusion depth into the matrix. It may overestimate the transport of tracers through the fractures, especially for the cases with large fracture spacing, and predict artificial early breakthroughs. The objective of this study is to develop a new theory for calculating the particle transfer probability to captures the transient features of the diffusion depth into the matrix within the framework of the dual-continuum random walk particle method (RWPM).

Download or read book DCPT written by and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Accurate and efficient simulation of chemical transport processes in the unsaturated zone of Yucca Mountain is important to evaluate the performance of the potential repository. The scale of the unsaturated zone model domain for Yucca Mountain (50 km2 area with a 600 meter depth to the water table) requires a large gridblock approach to efficiently analyze complex flow & transport processes. The conventional schemes based on finite element or finite difference methods perform well for dispersion-dominated transport, but are subject to considerable numerical dilution/dispersion for advection-dominated transport, especially when a large gridblock size is used. Numerical dispersion is an artificial, grid-dependent chemical spreading, especially for otherwise steep concentration fronts. One effective scheme to deal with numerical dispersion is the random walk particle method (RWPM). While significant progress has been made in developing RWPM algorithms and codes for single continuum systems, a random walk particle tracker, which can handle chemical transport in dual-continua (fractured porous media) associated with irregular grid systems, is still absent (to our knowledge) in the public domain. This is largely due to the lacking of rigorous schemes to deal with particle transfer between the continua, and efficient schemes to track particles in irregular grid systems. The main objectives of this study are (1) to develop approaches to extend RWPM from a single continuum to a dual-continua system; (2) to develop an efficient algorithm for tracking particles in 3D irregular grids; and (3) to integrate these approaches into an efficient and user-friendly software, DCPT, for simulating chemical transport in fractured porous media.

Download or read book Introduction to Modeling of Transport Phenomena in Porous Media written by Jacob Bear and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 575 pages. Available in PDF, EPUB and Kindle. Book excerpt: The main purpose of this book is to provide the theoretical background to engineers and scientists engaged in modeling transport phenomena in porous media, in connection with various engineering projects, and to serve as a text for senior and graduate courses on transport phenomena in porous media. Such courses are taught in various disciplines, e. g. , civil engineering, chemical engineering, reservoir engineering, agricultural engineering and soil science. In these disciplines, problems are encountered in which various extensive quantities, e. g. , mass and heat, are transported through a porous material domain. Often the porous material contains several fluid phases, and the various extensive quantities are transported simultaneously throughout the multiphase system. In all these disciplines, management decisions related to a system's development and its operation have to be made. To do so, the 'manager', or the planner, needs a tool that will enable him to forecast the response of the system to the implementation of proposed management schemes. This forecast takes the form of spatial and temporal distributions of variables that describe the future state of the considered system. Pressure, stress, strain, density, velocity, solute concentration, temperature, etc. , for each phase in the system, and sometime for a component of a phase, may serve as examples of state variables. The tool that enables the required predictions is the model. A model may be defined as a simplified version of the real (porous medium) system that approximately simulates the excitation-response relations of the latter.

Download or read book Fundamentals of Transport Phenomena in Porous Media written by Jacob Bear and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 988 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains the lectures presented at the NATO Advanced Study Institute that took place at the University of Delaware, Newark, Delaware, July 18-27, 1982. The purpose of this Institute was to provide an international forum for exchange of ideas and dissemination of knowledge on some selected topics in Mechanics of Fluids in Porous Media. Processes of transport of such extensive quantities as mass of a phase, mass of a component of a phase, momentum and/or heat occur in diversified fields, such as petroleum reservoir engineer ing, groundwater hydraulics, soil mechanics, industrial filtration, water purification, wastewater treatment, soil drainage and irri gation, and geothermal energy production. In all these areas, scientists, engineers and planners make use of mathematical models that describe the relevant transport processes that occur within porous medium domains, and enable the forecasting of the future state of the latter in response to planned activities. The mathe matical models, in turn, are based on the understanding of phenomena, often within the void space, and on theories that re late these phenomena to measurable quantities. Because of the pressing needs in areas of practical interest, such as the develop ment of groundwater resources, the control and abatement of groundwater contamination, underground energy storage and geo thermal energy production, a vast amount of research efforts in all these fields has contributed, especially in the last t~o decades, to our understanding and ability to describe transport phenomena.

Download or read book Computational Methods for Flow and Transport in Porous Media written by J.M. Crolet and published by Springer Science & Business Media. This book was released on 2013-03-14 with total page 372 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first Symposium on Recent Advances in Problems of Flow and Transport in Porous Media was held in Marrakech in June '96 and has provided a focus for the utilization of computer methods for solving the many complex problems encountered in the field of solute transport in porous media. This symposium has been successful in bringing together scientists, physicists, hydrogeologists, researchers in soil and fluid mechanics and engineers involved in this multidisciplinary subject. It is clear that the utilization of computer-based models in this domain is still rapidly expanding and that new and novel solutions are being developed. The contributed papers which form this book reflect the recent advances, in particular with respect to new methods, inverse problems, reactive transport, unsaturated media and upscaling. These have been subdivided into the following sections: I. Numerical methods II. Mass transport and heat transfer III. Comparison with experimentation and simulation of real cases This book contains reviewed articles of the top presentations held during the International Symposium on Computer Methods in Porous Media Engineering which took place in Giens (France) in October 1998. All of the presentations and the optimism shown during the meeting provided further evidence that computer modeling is making remarkable progress and is indeed becoming an essential toolkit in the field of porous media and solute transport. I believe that the content of this book provides evidence of this and furthermore gives a comprehensive review of the theoretical developments and applications.

Download or read book Solute Transport Modelling written by Randolf Rausch and published by . This book was released on 2005 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Geological Storage of CO2 in Deep Saline Formations written by Auli Niemi and published by Springer. This book was released on 2017-02-24 with total page 567 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book offers readers a comprehensive overview, and an in-depth understanding, of suitable methods for quantifying and characterizing saline aquifers for the geological storage of CO2. It begins with a general overview of the methodology and the processes that take place when CO2 is injected and stored in deep saline-water-containing formations. It subsequently presents mathematical and numerical models used for predicting the consequences of CO2 injection. This book provides descriptions of relevant experimental methods, from laboratory experiments to field scale site characterization and techniques for monitoring spreading of the injected CO2 within the formation. Experiences from a number of important field injection projects are reviewed, as are those from CO2 natural analog sites. Lastly, the book presents relevant risk management methods. Geological storage of CO2 is widely considered to be a key technology capable of substantially reducing the amount of CO2 released into the atmosphere, thereby reducing the negative impacts of such releases on the global climate. Around the world, projects are already in full swing, while others are now being initiated and executed to demonstrate the technology. Deep saline formations are the geological formations considered to hold the highest storage potential, due to their abundance worldwide. To date, however, these formations have been relatively poorly characterized, due to their low economic value. Accordingly, the processes involved in injecting and storing CO2 in such formations still need to be better quantified and methods for characterizing, modeling and monitoring this type of CO2 storage in such formations must be rapidly developed and refined.

Download or read book Geostatistics Valencia 2016 written by J. Jaime Gómez-Hernández and published by Springer. This book was released on 2017-03-07 with total page 949 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains selected contributions presented at the 10th International Geostatistics Congress held in Valencia from 5 to 9 September, 2016. This is a quadrennial congress that serves as the meeting point for any engineer, professional, practitioner or scientist working in geostatistics. The book contains carefully reviewed papers on geostatistical theory and applications in fields such as mining engineering, petroleum engineering, environmental science, hydrology, ecology, and other fields.

Download or read book The Handbook of Groundwater Engineering written by John H. Cushman and published by CRC Press. This book was released on 2016-11-25 with total page 1092 pages. Available in PDF, EPUB and Kindle. Book excerpt: This new edition adds several new chapters and is thoroughly updated to include data on new topics such as hydraulic fracturing, CO2 sequestration, sustainable groundwater management, and more. Providing a complete treatment of the theory and practice of groundwater engineering, this new handbook also presents a current and detailed review of how to model the flow of water and the transport of contaminants both in the unsaturated and saturated zones, covers the protection of groundwater, and the remediation of contaminated groundwater.