Download or read book Two D Simulations of Flow and Transport on a Meter Sized Unsaturated Fractured Tuff Block written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Two-D numerical flow and transport experiments were performed with a meter-sized unsaturated fractured block in an attempt to validate the active fracture model (AFM) by estimating [gamma], a positive constant relating the fraction of active fractures to the effective water saturation for the block. Two different models developed for the study include a discrete fracture network model (DFNM) and a dual continuum model (DCM). The DFNM served to synthetically generate experimental measurements for water flow rates and tracer breakthroughs, against which numerical simulation data with DCM was calibrated to estimate [gamma] values for the fracture network. Water flow rates were monitored at both top and bottom to find balanced (''pseudo-steady'') states, when a pulse of tracer injection was initiated from the top of the block. During the transient state, water flow rates in DCM did not closely predict the measurements from DFNM, which show step-wise increments with time. Based on goodness-of-fit values, the water flow rates in the range of 7.12 x 10[sup -8] and 7.12 x 10[sup -7] kg/s (0.2-2.0 % of the saturated flow rate) provide better estimates of [gamma]. The DCM may be not suitable to estimate [gamma] when the injection rates are too high or low. Water flows predominantly through a few major fractures as preferential fast flow when the injection rate is high (> 10% of saturated flow rate), and capillary pressure solely governs water flow when the injection rate is low (
Download or read book Numerical Simulation of Flow and Transport in Partially Saturated Fractured Tuff written by and published by . This book was released on 1983 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: The unsaturated, fractured tuff of Yucca Mountain in the Nevada Test Site is one of the target sites for geologic storage of high-level radioactive waste. A modeling study of flow and transport in this geologically complex site is presented. Numerical models of mass and heat flow in conjunction with analytical solutions are being used for sensitivity and pathway analysis studies and to aid in design and interpretation of laboratory and field flow and transport tests in tuff. 11 references, 9 figures, 1 table.
Download or read book Numerical Simulation of Air and Water flow Experiments in a Block of Variably Saturated Fractured Tuff from Yucca Mountain Nevada written by and published by . This book was released on 1998 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Conceptual Models of Flow and Transport in the Fractured Vadose Zone written by National Research Council and published by National Academies Press. This book was released on 2001-05-21 with total page 398 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fluid flow and solute transport within the vadose zone, the unsaturated zone between the land surface and the water table, can be the cause of expanded plumes arising from localized contaminant sources. An understanding of vadose zone processes is, therefore, an essential prerequisite for cost-effective contaminant remediation efforts. In addition, because such features are potential avenues for rapid transport of chemicals from contamination sources to the water table, the presence of fractures and other channel-like openings in the vadose zone poses a particularly significant problem, Conceptual Models of Flow and Transport in the Fractured Vadose Zone is based on the work of a panel established under the auspices of the U.S. National Committee for Rock Mechanics. It emphasizes the importance of conceptual models and goes on to review the conceptual model development, testing, and refinement processes. The book examines fluid flow and transport mechanisms, noting the difficulty of modeling solute transport, and identifies geochemical and environmental tracer data as important components of the modeling process. Finally, the book recommends several areas for continued research.
Download or read book Rock Fractures and Fluid Flow written by National Research Council and published by National Academies Press. This book was released on 1996-08-27 with total page 568 pages. Available in PDF, EPUB and Kindle. Book excerpt: Scientific understanding of fluid flow in rock fracturesâ€"a process underlying contemporary earth science problems from the search for petroleum to the controversy over nuclear waste storageâ€"has grown significantly in the past 20 years. This volume presents a comprehensive report on the state of the field, with an interdisciplinary viewpoint, case studies of fracture sites, illustrations, conclusions, and research recommendations. The book addresses these questions: How can fractures that are significant hydraulic conductors be identified, located, and characterized? How do flow and transport occur in fracture systems? How can changes in fracture systems be predicted and controlled? Among other topics, the committee provides a geomechanical understanding of fracture formation, reviews methods for detecting subsurface fractures, and looks at the use of hydraulic and tracer tests to investigate fluid flow. The volume examines the state of conceptual and mathematical modeling, and it provides a useful framework for understanding the complexity of fracture changes that occur during fluid pumping and other engineering practices. With a practical and multidisciplinary outlook, this volume will be welcomed by geologists, petroleum geologists, geoengineers, geophysicists, hydrologists, researchers, educators and students in these fields, and public officials involved in geological projects.
Download or read book Study of Unsaturated Zone Flow and Transport Models of Fractured Tuff written by John H. Kessler and published by . This book was released on 1998 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Flow and Transport in Saturated and Unsaturated Fractured Porous Media Development of Particle based Modeling Approaches written by Jannes Kordilla and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The main objective of this thesis is the development of particle-based flow and transport models to assist in the characterization of small-scale flow features and provide insight into the complex flow and transport dynamics on core- and fracture scales. Based on the evaluation of the simulation of flow in a fractured karst aquifer using a double continuum model and the Richards equation to describe unsaturated flow, the fundamental weaknesses of the approach are identified and new innovative methods are presented to capture the underlying preferential flow and transport features. The simul ...
Download or read book Measuring and Modeling Flow in Welded Fractured Tuffs written by and published by . This book was released on 2001 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: We have carried out a series of in situ liquid-release experiments in conjunction with a numerical modeling study to examine the effect of the rock matrix on liquid flow and transport occurring primarily through the fracture network. Field experiments were conducted in the highly fractured Topopah Spring welded tuff at a site accessed from the Exploratory Studies Facility (ESFS), an underground laboratory in the unsaturated zone at Yucca Mountain, Nevada. During the experiment, wetting-front movement, flow-field evolution, and drainage of fracture flow paths were evaluated. Modeling was used to aid in experimental design, predict experimental results, and study the physical processes accompanying liquid flow through unsaturated fractured welded tuff. Field experiments and modeling suggest that it may not be sufficient to conceptualize the fractured tuff as consisting of a single network of high-permeability fractures embedded in a low-permeability matrix. The need to include a secondary fracture network is demonstrated by comparison to the liquid flow observed in the field.
Download or read book Alternative Conceptual Models and Codes for Unsaturated Flow in Fractured Tuff written by Clifford K. Ho and published by . This book was released on 1995 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Groundwater travel time (GWTT) calculations will play an important role in addressing site-suitability criteria for the potential high-level nuclear waste repository at Yucca Mountain, Nevada. In support of these calculations, Preliminary assessments of the candidate codes and models are presented in this report. A series of benchmark studies have been designed to address important aspects of modeling flow through fractured media representative of flow at Yucca Mountain. Three codes (DUAL, FEHMN, and TOUGH 2) are compared in these benchmark studies. DUAL is a single-phase, isothermal, two-dimensional flow simulator based on the dual mixed finite element method. FEHMN is a nonisothermal, multiphase, multidimensional simulator based primarily on the finite element method. TOUGH2 is anon isothermal, multiphase, multidimensional simulator based on the integral finite difference method. Alternative conceptual models of fracture flow consisting of the equivalent continuum model (ECM) and the dual permeability (DK) model are used in the different codes.
Download or read book Numerical Simulation of Air and Water flow Experiments in a Block of Variably Saturated Fractured Tuff from Yucca Mountain Nevada written by and published by . This book was released on 1998 with total page 71 pages. Available in PDF, EPUB and Kindle. Book excerpt: Numerical models of water movement through variably saturated, fractured tuff have undergone little testing against experimental data collected from relatively well-controlled and characterized experiments. This report used the results of a multistage experiment on a block of variably saturated, fractured, welded tuff and associated core samples to investigate if those results could be explained using models and concepts currently used to simulate water movement in variably saturated, fractured tuff at Yucca Mountain, Nevada, the potential location of a high-level nuclear-waste repository. Aspects of the experiment were modeled with varying degrees of success. Imbibition experiments performed on cores of various lengths and diameters were adequately described by models using independently measured permeabilities and moisture-characteristic curves, provided that permeability reductions resulting from the presence of entrapped air were considered. Entrapped gas limited maximum water saturations during imbibition to approximately 0.70 to 0,80 of the fillable porosity values determined by vacuum saturation. A numerical simulator developed for application to fluid flow problems in fracture networks was used to analyze the results of air-injection tests conducted within the tuff block through 1.25-cm-diameter boreholes. These analyses produced estimates of transmissivity for selected fractures within the block. Transmissivities of other fractures were assigned on the basis of visual similarity to one of the tested fractures. The calibrated model explained 53% of the observed pressure variance at the monitoring boreholes (with the results for six outliers omitted) and 97% of the overall pressure variance (including monitoring and injection boreholes) in the subset of air-injection tests examined.
Download or read book Quarried block experiment numerical simulations of flow and transport experiments in a natural fracture written by D. J. Brush and published by . This book was released on 2003 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Three dimensional Modeling of Flow Through Fractured Tuff at Fran Ridge written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Numerical studies have been made of an infiltration experiment at Fran Ridge using the TOUGH2 code to aid in the selection of computational models for performance assessment. The exercise investigates the capabilities of TOUGH2 to model transient flows through highly fractured tuff and provides a possible means of calibration. Two distinctly different conceptual models were used in the TOUGH2 code, the dual permeability model and the equivalent continuum model. The infiltration test modeled involved the infiltration of dyed ponded water for 36 minutes. The 205 gallon filtration of water observed in the experiment was subsequently modeled using measured Fran Ridge fracture frequencies, and a specified fracture aperture of 285[mu]m. The dual permeability formulation predicted considerable infiltration along the fracture network, which was in agreement with the experimental observations. As expected, minimal fracture penetration of the infiltrating water was calculated using the equivalent continuum model, thus demonstrating that this model is not appropriate for modeling the highly transient experiment. It is therefore recommended that the dual permeability model be given priority when computing high-flux infiltration for use in performance assessment studies.
Download or read book Research Program to Develop and Validate Conceptual Models for Flow and Transport Through Unsaturated Fractured Rock Yucca Mountain Site Characterization Project written by and published by . This book was released on 1991 with total page 63 pages. Available in PDF, EPUB and Kindle. Book excerpt: As part of the Yucca Mountain Project, our research program to develop and validate conceptual models for flow and transport through unsaturated fractured rock integrates fundamental physical experimentation with conceptual model formulation and mathematical modeling. Our research is directed toward developing and validating macroscopic, continuum-based models and supporting effective property models because of their widespread utility within the context of this project. Success relative to the development and validation of effective property models is predicted on a firm understanding of the basic physics governing flow through fractured media, specifically in the areas of unsaturated flow and transport in a single fracture and fracture-matrix interaction.
Download or read book Numerical Simulation of Two dimensional Transient Flow and Solute Transport in Unsaturated Porous Media written by Jianhua Zou and published by . This book was released on 1989 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Numerical Methods for Fluid Flow in Unsaturated Heterogeneous Tuff written by and published by . This book was released on 1992 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: A numerical approach for modeling unsaturated flow is developed for heterogeneous simulations of fractured tuff generated using a geostatistical method. Cross correlations of hydrologic properties and upscaling of moisture retention curves is discussed. The approach is demonstrated for a study of infiltration at Yucca Mountain.
Download or read book Modeling Water Flow and Mass Transport in Fractured Porous Media written by Behshad Koohbor and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work addresses the numerical modeling of flow and mass transport in fractured porous media with a focus on two applications: seawater intrusion in coastal aquifers and flow in the fractured vadose zone. The main objectives of this work are to improve the efficiency and accuracy of numerical models to enhance their capacity in dealing with real-world studies. A significant part is dedicated to the development of semi-analytical solutions for seawater intrusion with the variable density flow model. These solutions are useful for benchmarking purposes and understanding the physical processes. An appropriate and robust technique based on surrogate modeling is also developed to investigate the uncertainties related to fractures on seawater intrusion. An efficient numerical scheme is developed for the simulation of variably saturated flow in fractured domains. The new developed scheme is used to investigate the effect of climate change on groundwater resources in a karst aquifer/spring system in Lebanon.
Download or read book Simulation of Fluid Flow and Transport of Solutes in Fractured Rock Using a Channel Network Model written by Björn Gylling and published by . This book was released on 1995 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt:
