Numerical investigation of nanoparticles transport in anisotropic porous media.
Salama, Amgad; Negara, Ardiansyah; El Amin, Mohamed; Sun, Shuyu
2015-10-01
In this work the problem related to the transport of nanoparticles in anisotropic porous media is investigated numerically using the multipoint flux approximation. Anisotropy of porous media properties is an essential feature that exists almost everywhere in subsurface formations. In anisotropic media, the flux and the pressure gradient vectors are no longer collinear and therefore interesting patterns emerge. The transport of nanoparticles in subsurface formations is affected by several complex processes including surface charges, heterogeneity of nanoparticles and soil grain collectors, interfacial dynamics of double-layer and many others. We use the framework of the theory of filtration in this investigation. Processes like particles deposition, entrapment, as well as detachment are accounted for. From the numerical methods point of view, traditional two-point flux finite difference approximation cannot handle anisotropy of media properties. Therefore, in this work we use the multipoint flux approximation (MPFA). In this technique, the flux components are affected by more neighboring points as opposed to the mere two points that are usually used in traditional finite volume methods. We also use the experimenting pressure field approach which automatically constructs the global system of equations by solving multitude of local problems. This approach facilitates to a large extent the construction of the global system. A set of numerical examples is considered involving two-dimensional rectangular domain. A source of nanoparticles is inserted in the middle of the anisotropic layer. We investigate the effects of both anisotropy angle and anisotropy ratio on the transport of nanoparticles in saturated porous media. It is found that the concentration plume and porosity contours follow closely the principal direction of anisotropy of permeability of the central domain.
Numerical investigation of nanoparticles transport in anisotropic porous media.
Salama, Amgad; Negara, Ardiansyah; El Amin, Mohamed; Sun, Shuyu
2015-10-01
In this work the problem related to the transport of nanoparticles in anisotropic porous media is investigated numerically using the multipoint flux approximation. Anisotropy of porous media properties is an essential feature that exists almost everywhere in subsurface formations. In anisotropic media, the flux and the pressure gradient vectors are no longer collinear and therefore interesting patterns emerge. The transport of nanoparticles in subsurface formations is affected by several complex processes including surface charges, heterogeneity of nanoparticles and soil grain collectors, interfacial dynamics of double-layer and many others. We use the framework of the theory of filtration in this investigation. Processes like particles deposition, entrapment, as well as detachment are accounted for. From the numerical methods point of view, traditional two-point flux finite difference approximation cannot handle anisotropy of media properties. Therefore, in this work we use the multipoint flux approximation (MPFA). In this technique, the flux components are affected by more neighboring points as opposed to the mere two points that are usually used in traditional finite volume methods. We also use the experimenting pressure field approach which automatically constructs the global system of equations by solving multitude of local problems. This approach facilitates to a large extent the construction of the global system. A set of numerical examples is considered involving two-dimensional rectangular domain. A source of nanoparticles is inserted in the middle of the anisotropic layer. We investigate the effects of both anisotropy angle and anisotropy ratio on the transport of nanoparticles in saturated porous media. It is found that the concentration plume and porosity contours follow closely the principal direction of anisotropy of permeability of the central domain. PMID:26212784
Numerical investigation of nanoparticles transport in anisotropic porous media
Salama, Amgad
2015-07-13
In this work the problem related to the transport of nanoparticles in anisotropic porous media is investigated numerically using the multipoint flux approximation. Anisotropy of porous media properties are an essential feature that exist almost everywhere in subsurface formations. In anisotropic media, the flux and the pressure gradient vectors are no longer collinear and therefore interesting patterns emerge. The transport of nanoparticles in subsurface formations is affected by several complex processes including surface charges, heterogeneity of nanoparticles and soil grain collectors, interfacial dynamics of double-layer and many others. We use the framework of the theory of filtration in this investigation. Processes like particles deposition, entrapment, as well as detachment are accounted for. From the numerical methods point of view, traditional two-point flux finite difference approximation cannot handle anisotropy of media properties. Therefore, in this work we use the multipoint flux approximation (MPFA). In this technique, the flux components are affected by more neighboring points as opposed to the mere two points that are usually used in traditional finite volume methods. We also use the experimenting pressure field approach which automatically constructs the global system of equations by solving multitude of local problems. This approach facilitates to a large extent the construction of the global system. A set of numerical examples is considered involving two-dimensional rectangular domain. A source of nanoparticles is inserted in the middle of the anisotropic layer. We investigate the effects of both anisotropy angle and anisotropy ratio on the transport of nanoparticles in saturated porous media. It is found that the concentration plume and porosity contours follow closely the principal direction of anisotropy of permeability of the central domain.
Fabric dependence of quasi-waves in anisotropic porous media.
Cardoso, Luis; Cowin, Stephen C
2011-05-01
Assessment of bone loss and osteoporosis by ultrasound systems is based on the speed of sound and broadband ultrasound attenuation of a single wave. However, the existence of a second wave in cancellous bone has been reported and its existence is an unequivocal signature of poroelastic media. To account for the fact that ultrasound is sensitive to microarchitecture as well as bone mineral density (BMD), a fabric-dependent anisotropic poroelastic wave propagation theory was recently developed for pure wave modes propagating along a plane of symmetry in an anisotropic medium. Key to this development was the inclusion of the fabric tensor--a quantitative stereological measure of the degree of structural anisotropy of bone--into the linear poroelasticity theory. In the present study, this framework is extended to the propagation of mixed wave modes along an arbitrary direction in anisotropic porous media called quasi-waves. It was found that differences between phase and group velocities are due to the anisotropy of the bone microarchitecture, and that the experimental wave velocities are more accurately predicted by the poroelastic model when the fabric tensor variable is taken into account. This poroelastic wave propagation theory represents an alternative for bone quality assessment beyond BMD. PMID:21568431
Effective stress law for anisotropic double porous media
Institute of Scientific and Technical Information of China (English)
ZHAO Ying; CHEN Mian; ZHANG Guangqing
2004-01-01
An effective stress law is derived analytically to describe the effect of pore (fracture pore and matrix-block pore) fluid pressure on the linearly elastic response of anisotropic saturated dual-porous rocks, which exhibit anisotropy. For general anisotropy the difference between the effective stress and the applied stress is not hydrostatic simply multiplied by Biot coefficient. The effective stress law involves four constants for transversely isotropic response; these constants can be expressed in terms of the moduli of the single porous material, double porous material and of the solid material. These expressions are simplified considerably when the anisotropy is structural rather than intrinsic, i.e. in the case of an isotropic solid material with an anisotropic pore structure. In this case the effective stress law involves grain bulk modulus, four moduli and two compliances of the porous material for transverse isotropy. The law reduces, in the case of isotropic response, to that suggested by Li Shuiquan (2001). And reduction to the single-porosity (derived analytically by Carroll (1979)) is presented to demonstrate the conceptual consistency of the proposed law.
Fabric dependence of quasi-waves in anisotropic porous media
Cardoso, Luis; Cowin, Stephen C.
2011-01-01
Assessment of bone loss and osteoporosis by ultrasound systems is based on the speed of sound and broadband ultrasound attenuation of a single wave. However, the existence of a second wave in cancellous bone has been reported and its existence is an unequivocal signature of poroelastic media. To account for the fact that ultrasound is sensitive to microarchitecture as well as bone mineral density (BMD), a fabric-dependent anisotropic poroelastic wave propagation theory was recently developed ...
Institute of Scientific and Technical Information of China (English)
CAI; Ruixian; GOU; Chenhua; ZHANG; Na
2005-01-01
Some algebraically explicit analytical solutions are derived for the anisotropic Brinkman model―an improved Darcy model―describing the natural convection in porous media. Besides their important theoretical meaning (for example, in analyzing the non-Darcy and anisotropic effects on the convection), such analytical solutions can be the benchmark solutions that can promote the development of computational heat and mass transfer. Some solutions considering the anisotropic effect of permeability have been given previously by the authors, and this paper gives solutions including the anisotropic effect of thermal conductivity and the effect of heat sources.
Coupling two-phase fluid flow with two-phase darcy flow in anisotropic porous media
Chen, J.
2014-06-03
This paper reports a numerical study of coupling two-phase fluid flow in a free fluid region with two-phase Darcy flow in a homogeneous and anisotropic porous medium region. The model consists of coupled Cahn-Hilliard and Navier-Stokes equations in the free fluid region and the two-phase Darcy law in the anisotropic porous medium region. A Robin-Robin domain decomposition method is used for the coupled Navier-Stokes and Darcy system with the generalized Beavers-Joseph-Saffman condition on the interface between the free flow and the porous media regions. Obtained results have shown the anisotropic properties effect on the velocity and pressure of the two-phase flow. 2014 Jie Chen et al.
Generalization of the van der Waals equation for anisotropic fluids in porous media
Holovko, Myroslav; Shmotolokha, Volodymyr
2015-01-01
The generalized van der Waals equation of state for anisotropic liquids in porous media consists of two terms.One of them is based on the equation of state for hard spherocylinders in random porous media obtained from the scaled particle theory.The second term is expressed in terms of the mean value of attractive intermolecular interactions.The obtained equation is used for the investigation of the gas-liquid-nematic phase behavior of a molecular system depending on the anisotropy of molecule...
Institute of Scientific and Technical Information of China (English)
蔡睿贤; 张娜
2002-01-01
Some algebraically explicit analytical solutions are derived for the anisotropic Brinkman model an improved Darcy model describing the natural convection in porous media. Besides their important theoretical meaning (for example, to analyze the non-Darcy and anisotropic effects on the convection), such analytical solutions can be the benchmark solutions to promoting the develop ment of computational heat and mass transfer. For instance, we can use them to check the accuracy,convergence and effectiveness of various numerical computational methods and to improve numerical calculation skills such as differential schemes and grid generation ways.
Computation of the transient flow in zoned anisotropic porous media by the boundary element method
Bruch, E.; Grilli, S.
Results on the application of the BEM to transient two-dimensional flows in zoned anisotropic porous media are presented, including the iterative calculation of the free surface seepage position. The classical BEM equations are discretized by linear, quadratic, or cubic elements, employing special singular numerical quadrature rules. The method is improved by the incorporation of a subregion division. The present technique is shown to be very accurate and to avoid previously encountered oscillation problems.
Debbaut, Charlotte; Vierendeels, Jan; Siggers, Jennifer H.; Repetto, Rodolfo; Monbaliu, Diethard; Segers, Patrick
2014-01-01
The hepatic blood circulation is complex, particularly at the microcirculatory level. Previously, 2D liver lobule models using porous media and a 3D model using real sinusoidal geometries have been developed. We extended these models to investigate the role of vascular septa (VS) and anisotropic permeability. The lobule was modelled as a hexagonal prism (with or without VS) and the tissue was treated as a porous medium (isotropic or anisotropic permeability). Models were solved using computat...
Energy Technology Data Exchange (ETDEWEB)
Berryman, J.G.
2009-11-20
Poroelastic analysis usually progresses from assumed knowledge of dry or drained porous media to the predicted behavior of fluid-saturated and undrained porous media. Unfortunately, the experimental situation is often incompatible with these assumptions, especially when field data (from hydrological or oil/gas reservoirs) are involved. The present work considers several different experimental scenarios typified by one in which a set of undrained poroelastic (stiffness) constants has been measured using either ultrasound or seismic wave analysis, while some or all of the dry or drained constants are normally unknown. Drained constants for such a poroelastic system can be deduced for isotropic systems from available data if a complete set of undrained compliance data for the principal stresses are available - together with a few other commonly measured quantities such as porosity, fluid bulk modulus, and grain bulk modulus. Similar results are also developed here for anisotropic systems having up to orthotropic symmetry if the system is granular (i.e., composed of solid grains assembled into a solid matrix, either by a cementation process or by applied stress) and the grains are known to be elastically homogeneous. Finally, the analysis is also fully developed for anisotropic systems with nonhomogeneous (more than one mineral type), but still isotropic, grains - as well as for uniform collections of anisotropic grains as long as their axes of symmetry are either perfectly aligned or perfectly random.
Transverse mixing in three-dimensional nonstationary anisotropic heterogeneous porous media
DEFF Research Database (Denmark)
Cirpka, Olaf; Chiogna, Gabriele; Rolle, Massimo;
2015-01-01
flow and transport results obtained for a nonstationary anisotropic log-hydraulic conductivity field to an equivalent stationary field with identical mean, variance, and two-point correlation function disregarding the nonstationarity. The nonstationary anisotropic field is affected by mean secondary......Groundwater plumes originating from continuously emitting sources are typically controlled by transverse mixing between the plume and reactants in the ambient solution. In two-dimensional domains, heterogeneity causes only weak enhancement of transverse mixing in steady-state flows. In three......-dimensional domains, more complex flow patterns are possible because streamlines can twist. In particular, spatially varying orientation of anisotropy can cause steady-state groundwater whirls. We analyze steady-state solute transport in three-dimensional locally isotropic heterogeneous porous media with blockwise...
Negara, Ardiansyah
2015-03-04
Numerical investigations of two-phase flows in anisotropic porous media have been conducted. In the flow model, the permeability has been considered as a full tensor and is implemented in the numerical scheme using the multipoint flux approximation within the framework of finite difference method. In addition, the experimenting pressure field approach is used to obtain the solution of the pressure field, which makes the matrix of coefficient of the global system easily constructed. A number of numerical experiments on the flow of two-phase system in two-dimensional porous medium domain are presented. In this work, the gravity is included in the model to capture the possible buoyancy-driven effects due to density differences between the two phases. Different anisotropy scenarios have been considered. From the numerical results, interesting patterns of the flow, pressure, and saturation fields emerge, which are significantly influenced by the anisotropy of the absolute permeability field. It is found that the two-phase system moves along the principal direction of anisotropy. Furthermore, the effects of anisotropy orientation on the flow rates and the cross flow index are also discussed in the paper.
Debbaut, Charlotte; Vierendeels, Jan; Siggers, Jennifer H; Repetto, Rodolfo; Monbaliu, Diethard; Segers, Patrick
2014-01-01
The hepatic blood circulation is complex, particularly at the microcirculatory level. Previously, 2D liver lobule models using porous media and a 3D model using real sinusoidal geometries have been developed. We extended these models to investigate the role of vascular septa (VS) and anisotropic permeability. The lobule was modelled as a hexagonal prism (with or without VS) and the tissue was treated as a porous medium (isotropic or anisotropic permeability). Models were solved using computational fluid dynamics. VS inclusion resulted in more spatially homogeneous perfusion. Anisotropic permeability resulted in a larger axial velocity component than isotropic permeability. A parameter study revealed that results are most sensitive to the lobule size and radial pressure drop. Our model provides insight into hepatic microhaemodynamics, and suggests that inclusion of VS in the model leads to perfusion patterns that are likely to reflect physiological reality. The model has potential for applications to unphysiological and pathological conditions. PMID:23237543
Debbaut, Charlotte; Vierendeels, Jan; Siggers, Jennifer H; Repetto, Rodolfo; Monbaliu, Diethard; Segers, Patrick
2014-01-01
The hepatic blood circulation is complex, particularly at the microcirculatory level. Previously, 2D liver lobule models using porous media and a 3D model using real sinusoidal geometries have been developed. We extended these models to investigate the role of vascular septa (VS) and anisotropic permeability. The lobule was modelled as a hexagonal prism (with or without VS) and the tissue was treated as a porous medium (isotropic or anisotropic permeability). Models were solved using computational fluid dynamics. VS inclusion resulted in more spatially homogeneous perfusion. Anisotropic permeability resulted in a larger axial velocity component than isotropic permeability. A parameter study revealed that results are most sensitive to the lobule size and radial pressure drop. Our model provides insight into hepatic microhaemodynamics, and suggests that inclusion of VS in the model leads to perfusion patterns that are likely to reflect physiological reality. The model has potential for applications to unphysiological and pathological conditions.
Yong Wang; Wenzheng Yue; Mo Zhang
2016-01-01
The anisotropic transport of thermal neutron in heterogeneous porous media is of great research interests in many fields. In this paper, it is the first time that a new model based on micron X-ray computed tomography (CT) has been proposed to simultaneously consider both the separation of matrix and pore and the distribution of mineral components. We apply the Monte Carlo method to simulate thermal neutrons transporting through the model along different directions, and meanwhile detect those ...
Non—Darcian and Anisotropic Effects on Natural Convection in Horizontal Porous Media Enclosure
Institute of Scientific and Technical Information of China (English)
ZhangJingzhou; SunRenqia
1996-01-01
Natural convection heat transfer in a horizontal enclosure filled with anisotropic porous media,being isothermally heated at bettom and cooled at top while the vertical walls being adiabatic,is numerically studied by applying the Brinkman model-a modified form of Darcy model giving consideratioin to the viscous effect.The results show that:(1)a larger permeability ratio(K*) causes a lower flow intensity in the enclosure and a smaller Nusselt number,all Nusselt numbers approach unity in the limit of K*→∞;a larger thermal conductivity ratio(λ*) causes a stranger distortion of isotherms in the enclosure and a higher flow velocity near the walls,all the Nusselt numbers approach unity in the limit of λ*-→0,the permeability and thermal conductivity ratios generally have opposing effects on the Nusselt number.(2) an increasing Darcy number decreases the flow intensity and heat tansfer rates,which is more significant at a lower permeability ratio.In particular,with K*≤0.25,the Nusselt number for Da=10-3 would differ from that of Darcy flow up to an amount of 30%,an analysis neglecting the non-Darican effect will inevitably be of considerable error.
Flow and dispersion in anisotropic porous media: a Lattice-Boltzmann study
Maggiolo, Dario; Guarnieri, Massimo
2016-01-01
Given their capability of spreading active chemical species and collecting electricity, porous media made of carbon fibers are extensively used as diffusion layers in energy storage systems, such as redox flow batteries. In spite of this, the dispersion dynamics of species inside porous media is still not well understood and often lends itself to different interpretations. Actually, the microscopic design of efficient porous media which can potentially and effectively improve the performances of flow batteries, is a still open challenge. The present study aims to investigate the effect of fibrous media micro-structure on dispersion, in particular the effect of fiber orientation on drag and dispersion dynamics. Several Lattice-Boltzmann simulations of {flows through} differently-oriented fibrous media coupled with Lagrangian simulations of particle tracers have been performed. Results show that orienting fibers preferentially along the streamwise direction minimizes the drag and maximizes the dispersion, which...
Institute of Scientific and Technical Information of China (English)
SunWeitao; YangHuizhu
2003-01-01
Based on the first-order Biot-equation with simplified coefficients, a staggered irregular-grid finite difference method (FDM) is developed to simulate elastic wave propagation in 3-D heterogeneous anisotropic porous media. The ‘slow' P wave in porous media wave simulation is highly dispersive. Finer grids are needed to get a precise wavefield calculation for models with curved interface and complex geometric structure. Fine grids in a global model greatly increase computation costs of regular grids scheme. Irregular fine or coarse grids in local fields not only cost less computing time than the conventional velocity-stress FDM, but also give a more accurate wavefield description. A dispersion analysis of the irregular-grid finite difference operator has confirmed the stability and high efficiency. The absorbing boundary condition is used to eliminate artificial reflections. Numerical examples show that this new irregular-grid finite difference method is of higher performance than conventional methods using regular rectangular grids in simulating elastic wave propagation in heterogeneous anisotropic porous media.
Negara, Ardiansyah
2014-04-21
Carbon dioxide (CO2) sequestration in saline aquifers is considered as one of the most viable and promising ways to reduce CO2 concentration in the atmosphere. CO2 is injected into deep saline formations at supercritical state where its density is smaller than the hosting brine. This motivates an upward motion and eventually CO2 is trapped beneath the cap rock. The trapped CO2 slowly dissolves into the brine causing the density of the mixture to become larger than the host brine. This causes gravitational instabilities that is propagated and magnified with time. In this kind of density-driven flows, the CO2-rich brines migrate downward while the brines with low CO2 concentration move upward. With respect to the properties of the subsurface aquifers, there are instances where saline formations can possess anisotropy with respect to their hydraulic properties. Such anisotropy can have significant effect on the onset and propagation of flow instabilities. Anisotropy is predicted to be more influential in dictating the direction of the convective flow. To account for permeability anisotropy, the method of multipoint flux approximation (MPFA) in the framework of finite differences schemes is used. The MPFA method requires more point stencil than the traditional two-point flux approximation (TPFA). For example, calculation of one flux component requires 6-point stencil and 18-point stencil in 2-D and 3-D cases, respectively. As consequence, the matrix of coefficient for obtaining the pressure fields will be quite complex. Therefore, we combine the MPFA method with the experimenting pressure field technique in which the problem is reduced to solving multitude of local problems and the global matrix of coefficients is constructed automatically, which significantly reduces the complexity. We present several numerical scenarios of density-driven flow simulation in homogeneous, layered, and heterogeneous anisotropic porous media. The numerical results emphasize the
Negara, Ardiansyah
2015-05-01
Anisotropy of hydraulic properties of the subsurface geologic formations is an essential feature that has been established as a consequence of the different geologic processes that undergo during the longer geologic time scale. With respect to subsurface reservoirs, in many cases, anisotropy plays significant role in dictating the direction of flow that becomes no longer dependent only on driving forces like the pressure gradient and gravity but also on the principal directions of anisotropy. Therefore, there has been a great deal of motivation to consider anisotropy into the subsurface flow and transport models. In this dissertation, we present subsurface flow modeling in single and dual continuum anisotropic porous media, which include the single-phase groundwater flow coupled with the solute transport in anisotropic porous media, the two-phase flow with gravity effect in anisotropic porous media, and the natural gas flow in anisotropic shale reservoirs. We have employed the multipoint flux approximation (MPFA) method to handle anisotropy in the flow model. The MPFA method is designed to provide correct discretization of the flow equations for general orientation of the principal directions of the permeability tensor. The implementation of MPFA method is combined with the experimenting pressure field approach, a newly developed technique that enables the solution of the global problem breaks down into the solution of multitude of local problems. The numerical results of the study demonstrate the significant effects of anisotropy of the subsurface formations. For the single-phase groundwater flow coupled with the solute transport modeling in anisotropic porous media, the results shows the strong impact of anisotropy on the pressure field and the migration of the solute concentration. For the two-phase flow modeling with gravity effect in anisotropic porous media, it is observed that the buoyancy-driven flow, which emerges due to the density differences between the
Wang, Yong; Yue, Wenzheng; Zhang, Mo
2016-06-01
The anisotropic transport of thermal neutron in heterogeneous porous media is of great research interests in many fields. In this paper, it is the first time that a new model based on micron X-ray computed tomography (CT) has been proposed to simultaneously consider both the separation of matrix and pore and the distribution of mineral components. We apply the Monte Carlo method to simulate thermal neutrons transporting through the model along different directions, and meanwhile detect those unreacted thermal neutrons by an array detector on the other side of the model. Therefore, the anisotropy of pore structure can be imaged by the amount of received thermal neutrons, due to the difference of rock matrix and pore-filling fluids in the macroscopic reaction cross section (MRCS). The new model has been verified by the consistent between the simulated data and the pore distribution from X-ray CT. The results show that the evaluation of porosity can be affected by the anisotropy of media. Based on the research, a new formula is developed to describe the correlation between the resolution of array detectors and the quality of imaging. The formula can be further used to analyze the critical resolution and the suitable number of thermal neutrons emitted in each simulation. Unconventionally, we find that a higher resolution cannot always lead to a better image.
Pore Structure Reconstruction and Moisture Migration in Porous Media
Zheng, Jiayi; Shi, Xing; Shi, Juan; Chen, Zhenqian
2014-09-01
Three kinds of porous media (isotropic, perpendicular anisotropic and parallel anisotropic porous media) with the same porosity, different pore size distributions and fractal spectral dimensions were reconstructed by random growth method. It was aimed to theoretically study the impact of microscopic pore structure on water vapor diffusion process in porous media. The results show that pore size distribution can only denote the static characteristics of porous media but cannot effectively reflect the dynamic transport characteristics of porous media. Fractal spectral dimension can effectively analyze and reflect pores connectivity and moisture dynamic transport properties of porous media from the microscopic perspective. The pores connectivity and water vapor diffusion performance in pores of porous media get better with the increase of fractal spectral dimension of porous media. Fractal spectral dimension of parallel anisotropic porous media is more than that of perpendicular anisotropic porous media. Fractal spectral dimension of isotropic porous media is between parallel anisotropic porous media and perpendicular anisotropic porous media. Other macroscopic parameters such as equilibrium diffusion coefficient of water vapor, water vapor concentration variation at right boundary in equilibrium, the time when water vapor diffusion process reaches a stable state also can characterize the pores connectivity and water vapor diffusion properties of porous media.
Salama, Amgad
2014-09-01
In this work we apply the experimenting pressure field approach to the numerical solution of the single phase flow problem in anisotropic porous media using the multipoint flux approximation. We apply this method to the problem of flow in saturated anisotropic porous media. In anisotropic media the component flux representation requires, generally multiple pressure values in neighboring cells (e.g., six pressure values of the neighboring cells is required in two-dimensional rectangular meshes). This apparently results in the need for a nine points stencil for the discretized pressure equation (27 points stencil in three-dimensional rectangular mesh). The coefficients associated with the discretized pressure equation are complex and require longer expressions which make their implementation prone to errors. In the experimenting pressure field technique, the matrix of coefficients is generated automatically within the solver. A set of predefined pressure fields is operated on the domain through which the velocity field is obtained. Apparently such velocity fields do not satisfy the mass conservation equations entailed by the source/sink term and boundary conditions from which the residual is calculated. In this method the experimenting pressure fields are designed such that the residual reduces to the coefficients of the pressure equation matrix. © 2014 Elsevier B.V. All rights reserved.
A review of a selection of papers describing the theory of transport in anisotropic porous media
International Nuclear Information System (INIS)
It is now generally accepted that the dispersion length, as defined in the classical advection-dispersion equation, is scale dependent. This report collects together and reviews some of the seminal papers in which have appeared the models and techniques that have led to our present understanding of solute transport in spatially stochastic media. Thus we examine the early work of Taylor on diffusion, the work of Saffman on capillaries, through to the more recent contributions of Dagan and Gelhar which regard the advective-dispersion equation as having stochastic parameters. The reports discuss these papers highlighting the physical arguments and in places deriving some of the more obscure results. This work is carried out by a cost-sharing contract with the European Atomic Energy Community for a research programme on Management, Storage and Radioactive waste disposal. 34 refs
Bejan, A
2006-01-01
Provides an introduction to convection in porous media, such as fibrous insulation, geological strata, and catalytic reactors. This third edition covers ""designed"" porous media, the theory of deformable media, modeling viscous dissipation in hyperporous media, and more. It is useful for researchers, practicing engineers and students.
Photon states in anisotropic media
Indian Academy of Sciences (India)
Deepak Kumar
2002-08-01
Quantum aspects of optical polarization are discussed for waves traveling in anisotropic dielectric media with a view to relate the dynamics of polarization with that of photon spin and its manipulation by classical polarizers.
Saad, Bilal Mohammed
2014-01-01
We study the convergence of a combined finite volume nonconforming finite element scheme on general meshes for a partially miscible two-phase flow model in anisotropic porous media. This model includes capillary effects and exchange between the phase. The diffusion term,which can be anisotropic and heterogeneous, is discretized by piecewise linear nonconforming triangular finite elements. The other terms are discretized by means of a cell-centered finite volume scheme on a dual mesh. The relative permeability of each phase is decentred according the sign of the velocity at the dual interface. The convergence of the scheme is proved thanks to an estimate on the two pressures which allows to show estimates on the discrete time and compactness results in the case of degenerate relative permeabilities. A key point in the scheme is to use particular averaging formula for the dissolution function arising in the diffusion term. We show also a simulation of CO
Stochastic porous media equations
Barbu, Viorel; Röckner, Michael
2016-01-01
Focusing on stochastic porous media equations, this book places an emphasis on existence theorems, asymptotic behavior and ergodic properties of the associated transition semigroup. Stochastic perturbations of the porous media equation have reviously been considered by physicists, but rigorous mathematical existence results have only recently been found. The porous media equation models a number of different physical phenomena, including the flow of an ideal gas and the diffusion of a compressible fluid through porous media, and also thermal propagation in plasma and plasma radiation. Another important application is to a model of the standard self-organized criticality process, called the "sand-pile model" or the "Bak-Tang-Wiesenfeld model". The book will be of interest to PhD students and researchers in mathematics, physics and biology.
Energy Technology Data Exchange (ETDEWEB)
Marsden, S.S.
1986-07-01
In 1978 a literature search on selective blocking of fluid flow in porous media was done by Professor S.S. Marsden and two of his graduate students, Tom Elson and Kern Huppy. This was presented as SUPRI Report No. TR-3 entitled ''Literature Preview of the Selected Blockage of Fluids in Thermal Recovery Projects.'' Since then a lot of research on foam in porous media has been done on the SUPRI project and a great deal of new information has appeared in the literature. Therefore we believed that a new, up-to-date search should be done on foam alone, one which would be helpful to our students and perhaps of interest to others. This is a chronological survey showing the development of foam flow, blockage and use in porous media, starting with laboratory studies and eventually getting into field tests and demonstrations. It is arbitrarily divided into five-year time periods. 81 refs.
Electromagnetism on anisotropic fractal media
Ostoja-Starzewski, Martin
2013-04-01
Basic equations of electromagnetic fields in anisotropic fractal media are obtained using a dimensional regularization approach. First, a formulation based on product measures is shown to satisfy the four basic identities of the vector calculus. This allows a generalization of the Green-Gauss and Stokes theorems as well as the charge conservation equation on anisotropic fractals. Then, pursuing the conceptual approach, we derive the Faraday and Ampère laws for such fractal media, which, along with two auxiliary null-divergence conditions, effectively give the modified Maxwell equations. Proceeding on a separate track, we employ a variational principle for electromagnetic fields, appropriately adapted to fractal media, so as to independently derive the same forms of these two laws. It is next found that the parabolic (for a conducting medium) and the hyperbolic (for a dielectric medium) equations involve modified gradient operators, while the Poynting vector has the same form as in the non-fractal case. Finally, Maxwell's electromagnetic stress tensor is reformulated for fractal systems. In all the cases, the derived equations for fractal media depend explicitly on fractal dimensions in three different directions and reduce to conventional forms for continuous media with Euclidean geometries upon setting these each of dimensions equal to unity.
DEFF Research Database (Denmark)
Yuan, Hao; Shapiro, Alexander
There is a considerable and ongoing effort aimed at understanding the transport and the deposition of suspended particles in porous media, especially non-Fickian transport and non-exponential deposition of particles. In this work, the influential parameters in filtration models are studied...
Experimental Evidence of Helical Flow in Porous Media
DEFF Research Database (Denmark)
Ye, Yu; Chiogna, Gabriele; Cirpka, Olaf A.;
2015-01-01
Helical flow leads to deformation of solute plumes and enhances transverse mixing in porous media. We present experiments in which macroscopic helical flow is created by arranging different materials to obtain an anisotropic macroscopic permeability tensor with spatially variable orientation. The...... mixers, but in porous media....
Nield, Donald A
2013-01-01
Convection in Porous Media, 4th Edition, provides a user-friendly introduction to the subject, covering a wide range of topics, such as fibrous insulation, geological strata, and catalytic reactors. The presentation is self-contained, requiring only routine mathematics and the basic elements of fluid mechanics and heat transfer. The book will be of use not only to researchers and practicing engineers as a review and reference, but also to graduate students and others entering the field. The new edition features approximately 1,750 new references and covers current research in nanofluids, cellular porous materials, strong heterogeneity, pulsating flow, and more. Recognized as the standard reference in the field Includes a comprehensive, 250-page reference list Cited over 2300 times to date in its various editions Serves as an introduction for those entering the field and as a comprehensive reference for experienced researchers Features new sections on nanofluids, carbon dioxide sequestration, and applications...
Nield, Donald A
1992-01-01
This book provides a user-friendly introduction to the topic of convection in porous media The authors as- sume that the reader is familiar with the basic elements of fluid mechanics and heat transfer, but otherwise the book is self-contained The book will be useful both as a review (for reference) and as a tutorial work, suitable as a textbook in a graduate course or seminar The book brings into perspective the voluminous research that has been performed during the last two decades The field has recently exploded because of worldwide concern with issues such as energy self-sufficiency and pollution of the environment Areas of application include the insulation of buildings and equipment, energy storage and recovery, geothermal reservoirs, nuclear waste disposal, chemical reactor engineering, and the storage of heat-generating materials such as grain and coal Geophysical applications range from the flow of groundwater around hot intrusions to the stability of snow against avalanches
Porous media geometry and transports
Adler, Pierre
1992-01-01
The goal of ""Porous Media: Geometry and Transports"" is to provide the basis of a rational and modern approach to porous media. This book emphasizes several geometrical structures (spatially periodic, fractal, and random to reconstructed) and the three major single-phase transports (diffusion, convection, and Taylor dispersion).""Porous Media"" serves various purposes. For students it introduces basic information on structure and transports. Engineers will find this book useful as a readily accessible assemblage of al the major experimental results pertaining to single-phase tr
Efficient Wavefield Extrapolation In Anisotropic Media
Alkhalifah, Tariq
2014-07-03
Various examples are provided for wavefield extrapolation in anisotropic media. In one example, among others, a method includes determining an effective isotropic velocity model and extrapolating an equivalent propagation of an anisotropic, poroelastic or viscoelastic wavefield. The effective isotropic velocity model can be based upon a kinematic geometrical representation of an anisotropic, poroelastic or viscoelastic wavefield. Extrapolating the equivalent propagation can use isotopic, acoustic or elastic operators based upon the determined effective isotropic velocity model. In another example, non-transitory computer readable medium stores an application that, when executed by processing circuitry, causes the processing circuitry to determine the effective isotropic velocity model and extrapolate the equivalent propagation of an anisotropic, poroelastic or viscoelastic wavefield. In another example, a system includes processing circuitry and an application configured to cause the system to determine the effective isotropic velocity model and extrapolate the equivalent propagation of an anisotropic, poroelastic or viscoelastic wavefield.
Anisotropic damage coupled modeling of saturated porous rock
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
It is widely acknowledged that the natural rock mass is anisotropic and its failing type is also non-isotropic. An orthotropic elastic damaged model has been proposed in which the elastic deformation,the damaged deformation and irreversible deformation can be identified respectively. A second rank damage tensor is employed to characterize the induced damage and damage evolution related to the propagation conditions of microcracks. A specific form of the Gibbs free energy function is used to obtain the effective elastic stiffness and the limited scopes of damage parameters are suggested. The model’s parameter determination is proposed by virtue of conventional tri-axial test. Then,the proposed model is developed to simulate the coupled hydraulic mechanical responses and traction behaviors in different loading paths of porous media.
Lifting a large object from an anisotropic porous bed
Karmakar, Timir; Raja Sekhar, G. P.
2016-09-01
An analytical study of two dimensional problem of lifting an object from the top of a fully saturated rigid porous bed is discussed. It is assumed that the porous bed is anisotropic in nature. The flow within the gap region between the object and the porous bed is assumed to be governed by Stokes equation while the flow within the porous bed is governed by Brinkman equation. The breakout phenomenon for different kinds of soil is reported. The effect of mechanical properties like anisotropic permeability, grain diameter size, and porosity on streamlines, velocity, and force is analyzed. Relevant comparison with C. C. Mei, R. W. Yeung, and K. F. Liu ["Lifting a large object from a porous bed," J. Fluid. Mech. 152, 203-215 (1985)] and Y. Chang, L. H. Huang and F. P. Y. Yang ["Two-dimensional lift-up problem for a rigid porous bed," Phys. Fluids, 27, 053101 (2015)] is done.
Generalized Jones matrices for anisotropic media.
Ortega-Quijano, Noé; Arce-Diego, José Luis
2013-03-25
The interaction of arbitrary three-dimensional light beams with optical elements is described by the generalized Jones calculus, which has been formally proposed recently [Azzam, J. Opt. Soc. Am. A 28, 2279 (2011)]. In this work we obtain the parametric expression of the 3×3 differential generalized Jones matrix (dGJM) for arbitrary optical media assuming transverse light waves. The dGJM is intimately connected to the Gell-Mann matrices, and we show that it provides a versatile method for obtaining the macroscopic GJM of media with either sequential or simultaneous anisotropic effects. Explicit parametric expressions of the GJM for some relevant optical elements are provided.
Resurgence flows in porous media
Adler, Pierre; Mityushev, Vladimir
2010-05-01
Porous media are generally described by the Darcy equation when the length scales are sufficiently large with respect to the pore scale. This approach is also applicable when the media are heterogeneous, i.e., when permeability varies with space which is the most common case. In addition, real media are very often fractured; for a long time, this complex physical problem has been schematized by the double porosity model devised by Barenblatt. More recently, these fractured media have been addressed with a detailed description of the fractures and of their hydrodynamic interaction with the surrounding porous medium. This approach will be briefly summarized and the main recent progress surveyed (2). There is another situation which occurs frequently in underground studies. One well is connected to a distant well while it is not connected to closer wells. Such a situation can only be understood if there is a direct link between the two connected wells and if this link has little if any hydrodynamic interaction with the porous medium that it crosses. This link can be a fracture or more likely a set of fractures. This phenomenon is called resurgence because of the obvious analogy with rivers which suddenly disappear underground and go out at the ground surface again. Similar ideas have already been developed in other fields. In Physics, random networks limited to nearest neighbors have been recently extended to small world models where distant vertices can be related directly by a link. The electrical testing of porous media by electrical probes located at the walls (electrical tomography) has been used frequently in Geophysics since it is a non-invasive technique; this classical technique corresponds exactly to the situation addressed here from a different perspective. Media with resurgences consist of a double structure (3). The first one which is continuous is described by Darcy law as usual. The second one models the resurgences by capillaries with impermeable walls
Simulation of uncompressible fluid flow through a porous media
Energy Technology Data Exchange (ETDEWEB)
Ramirez, A. [Instituto Politecnico Nacional (SEPI-ESIQIE-IPN), Unidad Profesional Zacatenco, Laboratorio de Analisis Met. (Edif. ' Z' y Edif. ' 6' P.B.), Mexico City (Mexico)], E-mail: adaramil@yahoo.com.mx; Gonzalez, J.L. [Instituto Politecnico Nacional (SEPI-ESIQIE-IPN), Unidad Profesional Zacatenco, Laboratorio de Analisis Met. (Edif. ' Z' y Edif. ' 6' P.B.), Mexico City (Mexico); Carrillo, F. [Instituto Politecnico Nacional (SEPI-CICATA-IPN), Unidad Altamira Tamaulipas, Mexico (Mexico); Lopez, S. [Instituto Mexicano del Petroleo (I.M.P.-D.F.), Mexico (Mexico)
2009-02-28
Recently, a great interest has been focused for investigations about transport phenomena in disordered systems. One of the most treated topics is fluid flow through anisotropic materials due to the importance in many industrial processes like fluid flow in filters, membranes, walls, oil reservoirs, etc. In this work is described the formulation of a 2D mathematical model to simulate the fluid flow behavior through a porous media (PM) based on the solution of the continuity equation as a function of the Darcy's law for a percolation system; which was reproduced using computational techniques reproduced using a random distribution of the porous media properties (porosity, permeability and saturation). The model displays the filling of a partially saturated porous media with a new injected fluid showing the non-defined advance front and dispersion of fluids phenomena.
Simulation of uncompressible fluid flow through a porous media
International Nuclear Information System (INIS)
Recently, a great interest has been focused for investigations about transport phenomena in disordered systems. One of the most treated topics is fluid flow through anisotropic materials due to the importance in many industrial processes like fluid flow in filters, membranes, walls, oil reservoirs, etc. In this work is described the formulation of a 2D mathematical model to simulate the fluid flow behavior through a porous media (PM) based on the solution of the continuity equation as a function of the Darcy's law for a percolation system; which was reproduced using computational techniques reproduced using a random distribution of the porous media properties (porosity, permeability and saturation). The model displays the filling of a partially saturated porous media with a new injected fluid showing the non-defined advance front and dispersion of fluids phenomena.
An eigen theory of static electromagnetic field for anisotropic media
Institute of Scientific and Technical Information of China (English)
Shao-hua GUO
2009-01-01
Static electromagnetic fields are studied based on standard spaces of the physical presentation,and the modal equations of static electromagnetic fields for anisotropic media are derived. By introducing a new set of first-order potential functions,several novel theoretical results are obtained. It is found that,for isotropic media,electric or magnetic potentials are scalar; while for anisotropic media,they are vectors. Magnitude and direction of the vector potentials are related to the anisotropic subspaces. Based on these results,we discuss the laws of static electromagnetic fields for anisotropic media.
A finite difference, multipoint flux numerical approach to flow in porous media: Numerical examples
Osman, Hossam
2012-06-17
It is clear that none of the current available numerical schemes which may be adopted to solve transport phenomena in porous media fulfill all the required robustness conditions. That is while the finite difference methods are the simplest of all, they face several difficulties in complex geometries and anisotropic media. On the other hand, while finite element methods are well suited to complex geometries and can deal with anisotropic media, they are more involved in coding and usually require more execution time. Therefore, in this work we try to combine some features of the finite element technique, namely its ability to work with anisotropic media with the finite difference approach. We reduce the multipoint flux, mixed finite element technique through some quadrature rules to an equivalent cell-centered finite difference approximation. We show examples on using this technique to single-phase flow in anisotropic porous media.
Propagation of waves in porous media
Çorapçıoplu, M. Yavuz; Tuncay, Kağan
1996-01-01
Wave propagation in porous media is of interest in various diversified areas of science and engineering. The theory of the phenomenon has been studied extensively in soil mechanics, seismology, acoustics, earthquake engineering, ocean engineering, geophysics, and many other disciplines. This review presents a general survey of the literature within the context of porous media mechanics. Following a review of the Biot's theory of wave propagation in linear, elastic, fluid saturated porous medi...
Fundamental Solution of the Anisotropic Porous Medium Equation
Institute of Scientific and Technical Information of China (English)
Bin Heng SONG; Huai Yu JIAN
2005-01-01
We establish the existence of fundamental solutions for the anisotropic porous medium equation, ut = ∑n i=1(umi)xixi in sRn × (0,∞), where m1,m2,..., and mn are positive constants satisfying min1≤i≤n{mi} ≤ 1, Σni=i mi ＞ n -- 2, and max1≤i≤n{mi} ≤1/n+ Σi=1 mi).
Spin and Orbital angular momentum propagation in anisotropic media: theory
Picón, Antonio; Benseny, Albert; Mompart, Jordi; Calvo, Gabriel F.
2011-01-01
This paper is devoted to study the propagation of light beams carrying orbital angular momentum in optically anisotropic media. We first review some properties of homogeneous anisotropic media, and describe how the paraxial formalism is modified in order to proceed with a new approach dealing with a general setting of paraxial propagation along uniaxial inhomogeneous media. This approach is suitable for describing the space-variant-optical-axis phase plates.
Scaling effect of breakthroughcharacter in porous media
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
Breakthrough phenomenon during fluids percolating through wet saturated porous layer is widely met in the study of heat and mass transfer in porous media. Breakthrough pressure (BP) is a characteristic pressure that indicates the intrinsic properties of seepage within porous media. Measuring results of BP for saturated narrow-sieved sand are reported here. The curve of BP varying with the height of porous layer was obtained. Experiment and analysis indicate that BP is independent of the height of particle packed layer if thick enough; however, when the height is less than a certain critical value, BP dimims hes with the decrease of the height according to a universal scaling law.
Fronts of Stress Wave in Anisotropic Piezoelectric Media
Institute of Scientific and Technical Information of China (English)
刘颖; 刘凯欣; 高凌天
2004-01-01
The characteristic of wave fronts in anisotropic piezoelectric media is analysed by adopting the generalized characteristic theory. Analytical expressions for wave velocities and wave fronts are formulated. Apart from the ordinary characteristics, a new phenomenon, energy velocity funnel, is formed on the wave fronts of quasitransverse waves in anisotropic piezoelectric materials. A three-dimensional representation of wave fronts in anisotropic piezoelectric materials is given for a better understanding of the new phenomena.
On full-tensor permeabilities of porous media from numerical solutions of the Navier-Stokes equation
Wang, Y.
2013-01-01
A numerical method is proposed to compute full-tensor permeability of porous media without artificial simplification. Navier-Stokes (N-S) equation and Darcy\\'s law are combined to design these numerical experiments. This method can successfully detect the permeability values in principle directions of the porous media and the anisotropic degrees. It is found that the same configuration of porous media may possess isotropic features at lower Reynolds numbers while manifesting anisotropic features at higher Reynolds numbers due to the nonlinearity from convection. Anisotropy becomes pronounced especially when convection is dominant. 2013 Yi Wang et al.
Multiphase flow in fractured porous media
Energy Technology Data Exchange (ETDEWEB)
Firoozabadi, A.
1995-02-01
The major goal of this research project was to improve the understanding of the gas-oil two-phase flow in fractured porous media. In addition, miscible displacement was studied to evaluate its promise for enhanced recovery.
Wave Propagation in Fractured Anisotropic Media
Shao, S.; Pyrak-Nolte, L. J.
2012-12-01
Discontinuities such as fractures, joints and faults occur in the Earth's crusts in a variety of rock types. While much theoretical, experimental and computational research have examined seismic wave propagation in fractured isotropic rock, few experimental studies have investigated seismic wave propagation in fractured anisotropic media. The co-existence of fractures and layers can complicate the interpretation of seismic properties because of the discrete guided modes that propagate along or are confined by the fractures. In this study, we use seismic arrays and acoustic wavefront imaging techniques to examine the competing sources of seismic anisotropy from fractures and from layers. Samples with textural anisotropy (100 mm x 100 mm x 100 mm) were fabricated from garolite, an epoxy - cloth laminate, with layer thickness 0f ~ 0.5 mm. Two sets of fractured samples were fabricated: (1) two single fractured samples with one fracture either parallel or (and) perpendicular to layers, and (2) four multi-fractured samples with 5 parallel fractures oriented either parallel, 30 degrees, 60 degrees or perpendicular to the layers. An intact sample containing no fractures was used as a standard orthorhombic medium for reference. Seismic arrays were used on the first set of samples to measure bulk waves and fracture interface waves as a function of stress. The seismic array contained two compressional and five shear-wave source-receiver pairs with a central frequency of 1 MHz. Shear wave transducers were polarized both perpendicular and parallel to the layering as well as to the fracture. Measurements were made for a range of stresses (0.4 - 4MPa). From these measurements it was observed that a fractured layered medium appears more isotropic or anisotropic than the orthorhombic background, depending on the orientation of the fracture relative to layers. The matrix anisotropy was recovered by increasing the normal stress on a fracture (i.e., by closing the fracture). For the
Multiparticle collision dynamics in porous media
Matyka, Maciej
2016-01-01
We adopt the multiparticle collision dynamics method to simulate fluid flows in porous media. For this, the particle-level drag force is introduced into the original algorithm. The force hinder the flow resulting in global resistance and decrease of permeability. The extended algorithm is validated in the flow through fully porous channel with analytical solution. Basic properties of the solver are investigated including its dependency of permeability on model parameters.
Fluid dynamics in porous media with Sailfish
Coelho, Rodrigo C. V.; Neumann, Rodrigo F.
2016-09-01
In this work we show the application of Sailfish to the study of fluid dynamics in porous media. Sailfish is an open-source software based on the lattice-Boltzmann method. This application of computational fluid dynamics is of particular interest to the oil and gas industry and the subject could be a starting point for an undergraduate or graduate student in physics or engineering. We built artificial samples of porous media with different porosities and used Sailfish to simulate the fluid flow through them in order to calculate their permeability and tortuosity. We also present a simple way to obtain the specific superficial area of porous media using Python libraries. To contextualise these concepts, we analyse the applicability of the Kozeny-Carman equation, which is a well-known permeability-porosity relation, to our artificial samples.
Cryptosporidium Parvum Transport Through Natural Porous Media
Araujo, J. B.; Santamaria, J.; Blandford, W. P.; Gerba, C. P.; Brusseau, M. L.
2005-12-01
The objective of this study was to quantify the transport of Cryptosporidium parvum through saturated natural porous media. A series of miscible-displacement experiments were conducted, varying the properties of the porous media and electrolyte solution to help elucidate retention mechanisms. Significant removal (~99%) of oocysts was observed for transport in a sandy soil. Similar removals were also observed for experiments conducted with deionized water in place of the 0.01M NaCl electrolyte solution and experiments with a sub sample of the sandy soil that was treated with nitric acid. Effluent recoveries were greater for experiments conducted using coarser porous media. These results indicate straining contributed to the retention of Cryptosporidium parvum in our system.
Fluid dynamics in porous media with Sailfish
Coelho, Rodrigo C. V.; Neumann, Rodrigo F.
2016-09-01
In this work we show the application of Sailfish to the study of fluid dynamics in porous media. Sailfish is an open-source software based on the lattice-Boltzmann method. This application of computational fluid dynamics is of particular interest to the oil and gas industry and the subject could be a starting point for an undergraduate or graduate student in physics or engineering. We built artificial samples of porous media with different porosities and used Sailfish to simulate the fluid flow through them in order to calculate their permeability and tortuosity. We also present a simple way to obtain the specific superficial area of porous media using Python libraries. To contextualise these concepts, we analyse the applicability of the Kozeny–Carman equation, which is a well-known permeability–porosity relation, to our artificial samples.
Trends in modeling of porous media combustion
Energy Technology Data Exchange (ETDEWEB)
Mujeebu, M. Abdul; Abdullah, M. Zulkifly [Porous Media Combustion Laboratory, School of Mechanical Engineering, Universiti Sains Malaysia, Engineering Campus, 14300 Nibong Tebal, Penang (Malaysia); Mohamad, A.A. [College of Engineering, Alfaisal University, Riyadh 11533, P.O. Box 50927 (Saudi Arabia); Bakar, M.Z. Abu [School of Chemical Engineering, Universiti Sains Malaysia, Engineering Campus, 14300 Nibong Tebal, Penang (Malaysia)
2010-12-15
Porous media combustion (PMC) has interesting advantages compared with free flame combustion due to higher burning rates, increased power dynamic range, extension of the lean flammability limits, and low emissions of pollutants. Extensive experimental and numerical works were carried out and are still underway, to explore the feasibility of this interesting technology for practical applications. For this purpose, numerical modeling plays a crucial role in the design and development of promising PMC systems. This article provides an exhaustive review of the fundamental aspects and emerging trends in numerical modeling of gas combustion in porous media. The modeling works published to date are reviewed, classified according to their objectives and presented with general conclusions. Numerical modeling of liquid fuel combustion in porous media is excluded. (author)
Fluid dynamics in porous media with Sailfish
Coelho, Rodrigo C V
2016-01-01
In this work we show the application of Sailfish to the study of fluid dynamics in porous media. Sailfish is an open-source software based on the lattice-Boltzmann method. This application of computational fluid dynamics is of particular interest to the oil and gas industry and the subject could be a starting point for an undergraduate or graduate student in physics or engineering. We built artificial samples of porous media with different porosities and used Sailfish to simulate the fluid flow through in order to calculate permeability and tortuosity. We also present a simple way to obtain the specific superficial area of porous media using Python libraries. To contextualize these concepts, we test the Kozeny--Carman equation, discuss its validity and calculate the Kozeny's constant for our artificial samples.
Explosion propagation in inert porous media.
Ciccarelli, G
2012-02-13
Porous media are often used in flame arresters because of the high surface area to volume ratio that is required for flame quenching. However, if the flame is not quenched, the flow obstruction within the porous media can promote explosion escalation, which is a well-known phenomenon in obstacle-laden channels. There are many parallels between explosion propagation through porous media and obstacle-laden channels. In both cases, the obstructions play a duel role. On the one hand, the obstruction enhances explosion propagation through an early shear-driven turbulence production mechanism and then later by shock-flame interactions that occur from lead shock reflections. On the other hand, the presence of an obstruction can suppress explosion propagation through momentum and heat losses, which both impede the unburned gas flow and extract energy from the expanding combustion products. In obstacle-laden channels, there are well-defined propagation regimes that are easily distinguished by abrupt changes in velocity. In porous media, the propagation regimes are not as distinguishable. In porous media the entire flamefront is affected, and the effects of heat loss, turbulence and compressibility are smoothly blended over most of the propagation velocity range. At low subsonic propagation speeds, heat loss to the porous media dominates, whereas at higher supersonic speeds turbulence and compressibility are important. This blending of the important phenomena results in no clear transition in propagation mechanism that is characterized by an abrupt change in propagation velocity. This is especially true for propagation velocities above the speed of sound where many experiments performed with fuel-air mixtures show a smooth increase in the propagation velocity with mixture reactivity up to the theoretical detonation wave velocity. PMID:22213663
Renormalized anisotropic exchange for representing heat assisted magnetic recording media
Energy Technology Data Exchange (ETDEWEB)
Jiao, Yipeng; Liu, Zengyuan; Victora, R. H., E-mail: victora@umn.edu [MINT Center, Electrical and Computer Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (United States)
2015-05-07
Anisotropic exchange has been incorporated in a description of magnetic recording media near the Curie temperature, as would be found during heat assisted magnetic recording. The new parameters were found using a cost function that minimized the difference between atomistic properties and those of renormalized spin blocks. Interestingly, the anisotropic exchange description at 1.5 nm discretization yields very similar switching and magnetization behavior to that found at 1.2 nm (and below) discretization for the previous isotropic exchange. This suggests that the increased accuracy of anisotropic exchange may also reduce the computational cost during simulation.
Renormalized anisotropic exchange for representing heat assisted magnetic recording media
International Nuclear Information System (INIS)
Anisotropic exchange has been incorporated in a description of magnetic recording media near the Curie temperature, as would be found during heat assisted magnetic recording. The new parameters were found using a cost function that minimized the difference between atomistic properties and those of renormalized spin blocks. Interestingly, the anisotropic exchange description at 1.5 nm discretization yields very similar switching and magnetization behavior to that found at 1.2 nm (and below) discretization for the previous isotropic exchange. This suggests that the increased accuracy of anisotropic exchange may also reduce the computational cost during simulation
Transport of subsurface bacteria in porous media
Energy Technology Data Exchange (ETDEWEB)
Bales, R.C.; Arnold, R.G.; Gerba, C.P.
1995-02-01
The primary objective of this study was to develop tools with which to measure the advective transport of microorganisms through porous media. These tools were then applied to investigate the sorptive properties of representative microorganisms that were selected at random from the DOE`s deep subsurface collection of bacterial, maintained at Florida State University. The transport screening procedure that arose from this study was also used to investigate biological factors that affect the transport/sorption of biocolloids during their movement through porous media with the bulk advective flow.
Experimental compaction of anisotropic granular media
Ribière, Philippe; RICHARD, Patrick; Bideau, Daniel; Delannay, Renaud
2005-01-01
We report on experiments to measure the temporal and spatial evolution of packin g arrangements of anisotropic and weakly confined granular material, using high-resolution $\\gamma$-ray adsorption. In these experiments, the particle configurations start from an initially disordered, low-packing-fraction state and under vertical solicitation s evolve to a dense state. We find that the packing fraction evolution is slowed by the grain anisotropy but, as for spherically shaped grains, can be well...
Porous media: Analysis, reconstruction and percolation
DEFF Research Database (Denmark)
Rogon, Thomas Alexander
1995-01-01
been determined. We have obtained results which indicate that the effect of spatial correlation does affect not only the percolation threshold but also the exponents with respect to the values known for random media. We have attempted to predict key percolation values for a continuous medium (i......Spatial structure of selected porous media has been analysed in terms of the two first spatial moments (i.e. porosity and autocorrelation). Having established directional isotropy in the three spatial planes, multiple geometrical features measured in 2-d are attempted generalized to 3-d using...... in binary fields. Percolation threshold of reconstructed porous media has been determined for different discretizations of a selected model correlation function. Also critical exponents such as the correlation length exponent v, the strength of the infinite network and the mean size of finite clusters have...
Dilution and reactive mixing in three-dimensional helical flows in porous media
Chiogna, Gabriele; Ye, Yu; Grathwohl, Peter; Cirpka, Olaf A.; Rolle, Massimo
2016-04-01
Dilution under steady-state flow and transport conditions in porous media occurs primarily by lateral mass exchange at the fringe of solute plumes. This process controls the fate and transport of scalars in groundwater and in chemical reactors and it is fundamental for the understanding of many reactive processes. Three-dimensional flow fields can be characterized by a complex topological structure, which may greatly influence dilution and dilution enhancement of dissolved plumes, which is quantified by the exponential of the Shannon entropy [1]. In previous works, we identified the necessary conditions to obtain helical flow fields in non-stationary anisotropic heterogeneous porous media [2, 3]. To prove our theoretical findings, we perform steady-state bench-scale experiments with a conservative tracer and we provide a model-based investigation of the results [4]. The relevance of transverse mixing enhancement for the case of reactive solute transport is computed numerically using, as metrics of mixing, the length of a reactive plume undergoing an instantaneous complete bimolecular reaction and its critical dilution index. [1] Cirpka O.A., Chiogna G., Rolle M. and A. Bellin (2015). Transverse mixing in three-dimensional non-stationary anisotropic heterogeneous porous media. Water Resources Research, 51, DOI: 10.1002/2014WR015331. [2] Chiogna G., Cirpka O.A., Rolle M. and A. Bellin (2015). Helical flow streamlines in three-dimensional nonstationary anisotropic heterogeneous porous media. Water Resources Research, 51, DOI:10.1002/2014WR015330. [3] Chiogna G., Rolle M., Bellin A. and O.A. Cirpka (2014). Helicity and flow topology in three dimensional porous media. Advances in Water Resources, 73, 134-143, DOI: 10.1016/j.advwatres.2014.06.017. [4] Ye Y., Chiogna G., Cirpka O.A., Grathwohl P., and M. Rolle (2015). Experimental evidence of helical flow in porous media. Phys. Rev. Lett., 115, 194502, DOI: 10.1103/PhysRevLett.115.194502
Inversions for MT data in 2D symmetrical anisotropic media
Institute of Scientific and Technical Information of China (English)
YANG Chang-fu; LIN Chang-you; SUN Chong-chi; LI Qing-he
2005-01-01
In the paper, a 2D symmetrical anisotropic medium whose strike agrees with one of the horizontal principal axes is considered to develop a corresponding inversion technique. In the specified conditions, if we assume an equivalent conductivity anisotropy in both the vertical and dipping directions, i.e., σzz=σyy, the differential equations obtained are formally the same as that for TE and TM modes in the 2D isotropic geoelectrical media. The same inversion technique as that in the 2D isotropic media can be employed to obtain the anisotropic conductivities. It means that the TE and TM inversion results in the isotropic media can be respectively thought as the resistivities in the two principal directions of the symmetrically anisotropic media, which has offered a new approach and a theoretical guidance for interpreting magnetotelluric data. And the inversion technique developed here is used to test the magnetotelluric data in the area of Tianzhu and Yongdeng in Gansu Province, so that the crust anisotropic geoelectrical structures in this region can be obtained.
Effective Elliptic Models for Efficient Wavefield Extrapolation in Anisotropic Media
Waheed, Umair bin
2014-05-01
Wavefield extrapolation operator for elliptically anisotropic media offers significant cost reduction compared to that of transversely isotropic media (TI), especially when the medium exhibits tilt in the symmetry axis (TTI). However, elliptical anisotropy does not provide accurate focusing for TI media. Therefore, we develop effective elliptically anisotropic models that correctly capture the kinematic behavior of the TTI wavefield. Specifically, we use an iterative elliptically anisotropic eikonal solver that provides the accurate traveltimes for a TI model. The resultant coefficients of the elliptical eikonal provide the effective models. These effective models allow us to use the cheaper wavefield extrapolation operator for elliptic media to obtain approximate wavefield solutions for TTI media. Despite the fact that the effective elliptic models are obtained by kinematic matching using high-frequency asymptotic, the resulting wavefield contains most of the critical wavefield components, including the frequency dependency and caustics, if present, with reasonable accuracy. The methodology developed here offers a much better cost versus accuracy tradeoff for wavefield computations in TTI media, considering the cost prohibitive nature of the problem. We demonstrate the applicability of the proposed approach on the BP TTI model.
Chaotic Mixing in Three Dimensional Porous Media
Lester, Daniel R; Borgne, Tanguy Le
2016-01-01
Under steady flow conditions, the topological complexity inherent to all random 3D porous media imparts complicated flow and transport dynamics. It has been established that this complexity generates persistent chaotic advection via a three-dimensional (3D) fluid mechanical analogue of the baker's map which rapidly accelerates scalar mixing in the presence of molecular di?usion. Hence pore-scale fluid mixing is governed by the interplay between chaotic advection, molecular di?usion and the broad (power-law) distribution of fluid particle travel times which arise from the non-slip condition at pore walls. To understand and quantify mixing in 3D porous media, we consider these processes in a model 3D open porous network and develop a novel stretching continuous time random walk (CTRW) which provides analytic estimates of pore-scale mixing which compare well with direct numerical simulations. We ?nd that chaotic advection inherent to 3D porous media imparts scalar mixing which scales exponentially with longitudi...
Porous media fluid transport and pore structure
Dullien, F A L
1992-01-01
This book examines the relationship between transport properties and pore structure of porous material. Models of pore structure are presented with a discussion of how such models can be used to predict the transport properties of porous media. Portions of the book are devoted to interpretations of experimental results in this area and directions for future research. Practical applications are given where applicable, and are expected to be useful for a large number of different fields, including reservoir engineering, geology, hydrogeology, soil science, chemical process engineering, biomedica
Heat transfers in porous media. Phase changes
International Nuclear Information System (INIS)
Phase change phenomena in porous media, like all poly-phase processes, are complex and still only partially understood. This article deals only with the liquid-vapor phase change (vaporization-condensation) because of its particular practical importance in numerous domains. Content: 1 - Fixing of a fluid constituent inside a porous matrix; 2 - mathematical modeling; 3 - example of reference situations: phase changes at temperatures below the saturation temperature (vaporization, condensation), phase changes at temperatures above the saturation temperature (condensation, vaporization-boiling); 4 - conclusion. (J.S.)
Quantum electrodynamics of inhomogeneous anisotropic media
Energy Technology Data Exchange (ETDEWEB)
Lopez, Adrian E.R.; Lombardo, Fernando C. [Ciudad Universitaria, Departamento de Fisica Juan Jose Giambiagi, Buenos Aires (Argentina); IFIBA CONICET-UBA, Facultad de Ciencias Exactas y Naturales, Buenos Aires (Argentina)
2015-02-01
In this work we calculate the closed time path generating functional for the electromagnetic (EM) field interacting with inhomogeneous anisotropic matter. For this purpose, we first find a general expression for the electromagnetic field's influence action from the interaction of the field with a composite environment consisting in the quantum polarization degrees of freedom in each point of space, at arbitrary temperatures, connected to thermal baths. Then we evaluate the generating functional for the gauge field, in the temporal gauge, by implementing the Faddeev-Popov procedure. Finally, through the point-splitting technique, we calculate closed expressions for the energy, the Poynting vector, and the Maxwell tensor in terms of the Hadamard propagator. We show that all the quantities have contributions from the field's initial conditions and also from the matter degrees of freedom. Throughout the whole work we discuss how the gauge invariance must be treated in the formalism when the EM-field is interacting with inhomogeneous anisotropic matter. We study the electrodynamics in the temporal gauge, obtaining the EM-field's equation and a residual condition. Finally we analyze the case of the EM-field in bulk material and also discuss several general implications of our results in relation with the Casimir physics in a non-equilibrium scenario. (orig.)
Finite volume hydromechanical simulation in porous media
Nordbotten, Jan Martin
2014-05-01
Cell-centered finite volume methods are prevailing in numerical simulation of flow in porous media. However, due to the lack of cell-centered finite volume methods for mechanics, coupled flow and deformation is usually treated either by coupled finite-volume-finite element discretizations, or within a finite element setting. The former approach is unfavorable as it introduces two separate grid structures, while the latter approach loses the advantages of finite volume methods for the flow equation. Recently, we proposed a cell-centered finite volume method for elasticity. Herein, we explore the applicability of this novel method to provide a compatible finite volume discretization for coupled hydromechanic flows in porous media. We detail in particular the issue of coupling terms, and show how this is naturally handled. Furthermore, we observe how the cell-centered finite volume framework naturally allows for modeling fractured and fracturing porous media through internal boundary conditions. We support the discussion with a set of numerical examples: the convergence properties of the coupled scheme are first investigated; second, we illustrate the practical applicability of the method both for fractured and heterogeneous media.
2D seismic reflection tomography in strongly anisotropic media
Huang, Guangnan; Zhou, Bing; Li, Hongxi; Zhang, Hua; Li, Zelin
2014-12-01
Seismic traveltime tomography is an effective method to reconstruct underground anisotropic parameters. Currently, most anisotropic tomographic methods were developed under the assumption of weak anisotropy. The tomographic method proposed here can be implemented for imaging subsurface targets in strongly anisotropic media with a known tilted symmetry axis, since the adopted ray tracing method is suitable for anisotropic media with arbitrary degree. There are three kinds of reflection waves (qP, qSV and qSH waves) that were separately used to invert the blocky abnormal body model. The reflection traveltime tomographiy is developed here because a surface observation system is the most economical and practical way compared with crosswell and VSP. The numerical examples show that the traveltimes of qP reflection wave have inverted parameters {{c}11},{{c}13},{{c}33} \\text{and} {{c}44} successfully. Traveltimes of qSV reflection wave have inverted parameters {{c}11},{{c}33} \\text{and} {{c}44} successfully, with the exception of the {{c}13}, since it is less sensitive than other parameters. Traveltimes of qSH reflection wave also have inverted parameters {{c}44} \\text{and} {{c}66} successfully. In addition, we find that the velocity sensitivity functions (derivatives of phase velocity with respect to elastic moduli parameters) and raypath illuminating angles have a great influence on the qualities of tomograms according to the inversion of theoretical models. Finally, the numerical examples confirm that the reflection traveltime tomography can be applied to invert strongly anisotropic models.
Quantum electrodynamics of inhomogeneous anisotropic media
Lopez, Adrian E Rubio
2014-01-01
In this work we calculate the closed time path (CTP) generating functional for the electromagnetic (EM) field interacting with inhomogeneous anisotropic matter. For this purpose, we first find a general expression for the electromagnetic field's influence action from the interaction of the field with a composite environment consisting in the quantum polarization degrees of freedom in each point of space, at arbitrary temperatures, connected to thermal baths. Then, we evaluate the generating functional for the gauge field, in the temporal gauge, by implementing the Faddeev-Popov procedure. Finally, through the point-splitting technique, we calculate closed expressions for the energy, the Poynting vector and the Maxwell tensor in terms of the Hadamard propagator. We show that all the quantities have contributions from the field's initial conditions and also from the matter degrees of freedom. Throughout the whole work we discuss and give insights about how the gauge invariance must be treated in the formalism w...
Pulse splitting in nonlinear media with anisotropic dispersion properties
DEFF Research Database (Denmark)
Bergé, L.; Juul Rasmussen, J.; Schmidt, M.R.
1998-01-01
to a singularity in the transverse plane. Instead, the pulse spreads out along the direction of negative dispersion and splits up into small-scale cells, which may undergo further splitting events. The analytical results are supported by direct numerical solutions of the three dimensional cubic Schrodinger......The nonlinear self-focusing of beams in media with anisotropic (mix-signed) dispersion is investigated. Theoretical predictions employing virial-type arguments and self-similar techniques suggest that a pulse propagating in a nonlinear medium with anisotropic dispersion will not collapse...
Surface waves in ﬁbre-reinforced anisotropic elastic media
Indian Academy of Sciences (India)
P R Sengupta; Sisir Nath
2001-08-01
The aim of this paper is to investigate surface waves in anisotropic ﬁbre-reinforced solid elastic media. First, the theory of general surface waves has been derived and applied to study the particular cases of surface waves – Rayleigh, Love and Stoneley types. The wave velocity equations are found to be in agreement with the corresponding classical result when the anisotropic elastic parameters tends to zero. It is important to note that the Rayleigh type of wave velocity in the ﬁbre-reinforced elastic medium increases to a considerable amount in comparison with the Rayleigh wave velocity in isotropic materials.
Theory of porous media - past and present
Energy Technology Data Exchange (ETDEWEB)
Boer, R. de [Essen Univ. (Germany). Inst. fuer Mechanik
1998-10-01
Porous solids filled with liquid or gas play an important role in engineering, e.g., in material science, petroleum industry, chemical engineering, and soil mechanics as well as in biomechanics. Although porous media are of considerable practical significance the description of their mechanical and thermodynamical behavior has been unsatisfactory for a long time. The theory to describe the complex thermodynamical behavior of such saturated porous solids has come to certain well-founded conclusions only recently. It is the goal of this paper to show the historical development of the porous media theory, which already started in the eighteenth century, formed in some areas by polemic disputes and tragic events in the lifes of the scientists involved. Furthermore, the current state of the research into this subject is discussed, whereby the state of the development of the material independent basic equations and the constitutive theory is illustrated. For a certain class of models general theorems, such as minimum and maximum problems, are derived and the uniqueness of solutions of boundary value problems is proved. (orig.)
Magnetic Fluid Flows in Porous Media
Institute of Scientific and Technical Information of China (English)
LI Ming-Jun; CHEN Liang
2011-01-01
@@ The seepage law under a magnetic field is obtained by up-scaling the flow at the pore scale of rigid porous media,and the macroscopic equivalent model is also obtained.It is proved that the macroscopic mass flow depends on the macroscopic magnetic force and the gradients of pressure and of magnetic pressure, as Zahn and Rosensweig have described in their experiments.The permeability tensor is symmetric and positive.
Wave propagation in fractured porous media
Tuncay, Kağan; Çorapçıoplu, M. Yavuz
1996-01-01
A theory of wave propagation in fractured porous media is presented based on the double-porosity concept. The macroscopic constitutive relations and mass and momentum balance equations are obtained by volume averaging the microscale balance and constitutive equations and assuming small deformations. In microscale, the grains are assumed to be linearly elastic and the fluids are Newtonian. Momentum transfer terms are expressed in terms of intrinsic and relative permeabilities assuming the vali...
Finite volume hydromechanical simulation in porous media
Nordbotten, Jan Martin
2014-01-01
Cell-centered finite volume methods are prevailing in numerical simulation of flow in porous media. However, due to the lack of cell-centered finite volume methods for mechanics, coupled flow and deformation is usually treated either by coupled finite-volume-finite element discretizations, or within a finite element setting. The former approach is unfavorable as it introduces two separate grid structures, while the latter approach loses the advantages of finite volume methods for the flow equ...
Finite-size anisotropy in statistically uniform porous media
Koza, Zbigniew; Khalili, Arzhang
2009-01-01
Anisotropy of the permeability tensor in statistically uniform porous media of sizes used in typical computer simulations is studied. Although such systems are assumed to be isotropic by default, we show that de facto their anisotropic permeability can give rise to significant changes of transport parameters such as permeability and tortuosity. The main parameter controlling the anisotropy is $a/L$, being the ratio of the obstacle to system size. Distribution of the angle $\\alpha$ between the external force and the volumetric fluid stream is found to be approximately normal, and the standard deviation of $\\alpha$ is found to decay with the system size as $(a/L)^{d/2}$, where $d$ is the space dimensionality. These properties can be used to estimate both anisotropy-related statistical errors in large-scale simulations and the size of the representative elementary volume.
OPM: The Open Porous Media Initiative
Flemisch, B.; Flornes, K. M.; Lie, K.; Rasmussen, A.
2011-12-01
The principal objective of the Open Porous Media (OPM) initiative is to develop a simulation suite that is capable of modeling industrially and scientifically relevant flow and transport processes in porous media and bridge the gap between the different application areas of porous media modeling, including reservoir mechanics, CO2 sequestration, biological systems, and product development of engineered media. The OPM initiative will provide a long-lasting, efficient, and well-maintained open-source software for flow and transport in porous media built on modern software principles. The suite is released under the GNU General Public License (GPL). Our motivation is to provide a means to unite industry and public research on simulation of flow and transport in porous media. For academic users, we seek to provide a software infrastructure that facilitates testing of new ideas on models with industry-standard complexity, while at the same time giving the researcher control over discretization and solvers. Similarly, we aim to accelerate the technology transfer from academic institutions to professional companies by making new research results available as free software of professional standard. The OPM initiative is currently supported by six research groups in Norway and Germany and funded by existing grants from public research agencies as well as from Statoil Petroleum and Total E&P Norge. However, a full-scale development of the OPM initiative requires substantially more funding and involvement of more research groups and potential end users. In this talk, we will provide an overview of the current activities in the OPM initiative. Special emphasis will be given to the demonstration of the synergies achieved by combining the strengths of individual open-source software components. In particular, a new fully implicit solver developed within the DUNE-based simulator DuMux could be enhanced by the ability to read industry-standard Eclipse input files and to run on
Equilibrium and transfer in porous media 2 transfer laws
Daïan, Jean-François
2014-01-01
A porous medium is composed of a solid matrix and its geometrical complement: the pore space. This pore space can be occupied by one or more fluids. The understanding of transport phenomena in porous media is a challenging intellectual task. This book provides a detailed analysis of the aspects required for the understanding of many experimental techniques in the field of porous media transport phenomena. It is aimed at studentsor engineers who may not be looking specifically to become theoreticians in porous media, but wish to integrate knowledge of porous media with their previous scientif
Stability of Poiseuille flow in a fluid overlying an anisotropic and inhomogeneous porous layer
Deepu, P.; Anand, Prateek; Basu, Saptarshi
2015-08-01
We present the linear stability analysis of horizontal Poiseuille flow in a fluid overlying a porous medium with anisotropic and inhomogeneous permeability. The generalized Darcy model is used to describe the flow in the porous medium with the Beavers-Joseph condition at the interface of the two layers and the eigenvalue problem is solved numerically. The effect of major system parameters on the stability characteristics is addressed in detail. It is shown that the anisotropic and inhomogeneous modulation of the permeability of the underlying porous layer provides an effective means for passive control of the flow stability.
Reciprocal relations for effective conductivities of anisotropic media
Nevard, John; Keller, Joseph B.
1985-11-01
Any pair of two-dimensional anisotropic media with local conductivity tensors that are functions of position and that are related to one another in a certain reciprocal way are considered. It is proved that their effective conductivity tensors are related to each other in the same way for both spatially periodic media and statistically stationary random media. An inequality involving the effective conductivity tensors of two three-dimensional media that are reciprocally related is also proved. These results extend the corresponding results for locally isotropic media obtained by Keller, Mendelsohn, Hansen, Schulgasser, and Kohler and Papanicolau. They also yield a relation satisfied by the effective conductivity tensor of a medium reciprocal to a translated or rotated copy of itself.
Effective wavefield extrapolation in anisotropic media: Accounting for resolvable anisotropy
Alkhalifah, Tariq Ali
2014-04-30
Spectral methods provide artefact-free and generally dispersion-free wavefield extrapolation in anisotropic media. Their apparent weakness is in accessing the medium-inhomogeneity information in an efficient manner. This is usually handled through a velocity-weighted summation (interpolation) of representative constant-velocity extrapolated wavefields, with the number of these extrapolations controlled by the effective rank of the original mixed-domain operator or, more specifically, by the complexity of the velocity model. Conversely, with pseudo-spectral methods, because only the space derivatives are handled in the wavenumber domain, we obtain relatively efficient access to the inhomogeneity in isotropic media, but we often resort to weak approximations to handle the anisotropy efficiently. Utilizing perturbation theory, I isolate the contribution of anisotropy to the wavefield extrapolation process. This allows us to factorize as much of the inhomogeneity in the anisotropic parameters as possible out of the spectral implementation, yielding effectively a pseudo-spectral formulation. This is particularly true if the inhomogeneity of the dimensionless anisotropic parameters are mild compared with the velocity (i.e., factorized anisotropic media). I improve on the accuracy by using the Shanks transformation to incorporate a denominator in the expansion that predicts the higher-order omitted terms; thus, we deal with fewer terms for a high level of accuracy. In fact, when we use this new separation-based implementation, the anisotropy correction to the extrapolation can be applied separately as a residual operation, which provides a tool for anisotropic parameter sensitivity analysis. The accuracy of the approximation is high, as demonstrated in a complex tilted transversely isotropic model. © 2014 European Association of Geoscientists & Engineers.
Characteristics of Plane Wave Propagation in Biaxially Anisotropic Gyrotropic Media
Institute of Scientific and Technical Information of China (English)
PAN Wei-Tao; LIU Song-Hua; QIU Zhi-Liang
2012-01-01
Propagation characteristics of electromagnetic waves at the interface between an isotropic regular medium and a biaxially anisotropic gyrotropic medium are investigated.The results indicate that the reflection and refract ionproperties of electromagnetic waves are closely dependent on the dispersion relation of the gyrotropic media,and that anomalous total reflection and negative refraction may occur.The existence conditions of total transmission are also considered.It is found that total transmission arises when the TE-polarized incident waves are normal to the interface and the physical parameters of the two media are chosen properly,which are quite different from the existence conditions of total transmission at the anisotropic left-handed material interface.Numerical resul tsare given to validate our theoretical analysis.
Wave propagation in layered anisotropic media with application to composites
Nayfeh, AH
1995-01-01
Recent advances in the study of the dynamic behavior of layered materials in general, and laminated fibrous composites in particular, are presented in this book. The need to understand the microstructural behavior of such classes of materials has brought a new challenge to existing analytical tools. This book explores the fundamental question of how mechanical waves propagate and interact with layered anisotropic media. The chapters are organized in a logical sequence depending upon the complexity of the physical model and its mathematical treatment.
Anisotropic parameter inversion in VTI media using diffraction data
Waheed, Umair bin
2013-09-22
Diffracted waves contain useful information regarding the subsurface geometry and velocity. They are particularly valuable for anisotropic media as they inherently possess a wide range of dips necessary to resolve angular dependence of velocity. Using this property of diffraction data to our vantage, we develop an algorithm to invert for effective η model, assuming no prior knowledge of it. The obtained effective η model is then converted to interval η model using Dix-type inversion formula. The effectiveness of this approach is tested on the VTI Marmousi model, which yields good structural match even for a highly complex media such as the Marmousi model.
An efficient wave extrapolation method for anisotropic media with tilt
Waheed, Umair bin
2015-03-23
Wavefield extrapolation operators for elliptically anisotropic media offer significant cost reduction compared with that for the transversely isotropic case, particularly when the axis of symmetry exhibits tilt (from the vertical). However, elliptical anisotropy does not provide accurate wavefield representation or imaging for transversely isotropic media. Therefore, we propose effective elliptically anisotropic models that correctly capture the kinematic behaviour of wavefields for transversely isotropic media. Specifically, we compute source-dependent effective velocities for the elliptic medium using kinematic high-frequency representation of the transversely isotropic wavefield. The effective model allows us to use cheaper elliptic wave extrapolation operators. Despite the fact that the effective models are obtained by matching kinematics using high-frequency asymptotic, the resulting wavefield contains most of the critical wavefield components, including frequency dependency and caustics, if present, with reasonable accuracy. The methodology developed here offers a much better cost versus accuracy trade-off for wavefield computations in transversely isotropic media, particularly for media of low to moderate complexity. In addition, the wavefield solution is free from shear-wave artefacts as opposed to the conventional finite-difference-based transversely isotropic wave extrapolation scheme. We demonstrate these assertions through numerical tests on synthetic tilted transversely isotropic models.
Fluid flow and heat transfer in rotating porous media
Vadasz, Peter
2016-01-01
This Book concentrates the available knowledge on rotating fluid flow and heat transfer in porous media in one single reference. Dr. Vadasz develops the fundamental theory of rotating flow and heat transfer in porous media and introduces systematic classification and identification of the relevant problems. An initial distinction between rotating flows in isothermal heterogeneous porous systems and natural convection in homogeneous non-‐isothermal porous systems provides the two major classes of problems to be considered. A few examples of solutions to selected problems are presented, highlighting the significant impact of rotation on the flow in porous media.
Fractal Character for Tortuous Streamtubes in Porous Media
Institute of Scientific and Technical Information of China (English)
YU Bo-Ming
2005-01-01
@@ An analytical modelfor fractal dimension of tortuous streamtubes in porous media is derived. The proposed fractal dimension for tortuous streamtubes in porous media is expressed as a function of porosity and scale, and there is no empirical constant in the proposed expression. The model predictions for the fractal dimension oftortuous streamtubes in porous media are in good agreement with those by the box-counting method and with the observations of other researchers.
Diffusion of oriented particles in porous media
Energy Technology Data Exchange (ETDEWEB)
Haber, René [Institut für Physik, Technische Universität Chemnitz, D-09107 Chemnitz (Germany); Centre for Nonlinear Studies, Institute of Cybernetics at Tallinn University of Technology, Akadeemia tee 21, 12618 Tallinn (Estonia); Prehl, Janett [Institut für Physik, Technische Universität Chemnitz, D-09107 Chemnitz (Germany); Herrmann, Heiko [Centre for Nonlinear Studies, Institute of Cybernetics at Tallinn University of Technology, Akadeemia tee 21, 12618 Tallinn (Estonia); Hoffmann, Karl Heinz, E-mail: hoffmann@physik.tu-chemnitz.de [Institut für Physik, Technische Universität Chemnitz, D-09107 Chemnitz (Germany)
2013-11-29
Diffusion of particles in porous media often shows subdiffusive behavior. Here, we analyze the dynamics of particles exhibiting an orientation. The features we focus on are geometrical restrictions and the dynamical consequences of the interactions between the local surrounding structure and the particle orientation. This interaction can lead to particles getting temporarily stuck in parts of the structure. Modeling this interaction by a particular random walk dynamics on fractal structures we find that the random walk dimension is not affected while the diffusion constant shows a variety of interesting and surprising features.
Dynamics of clogging in drying porous media
Kaplan, C. Nadir; Mahadevan, L.
2014-11-01
Drying in porous media pervades a range of phenomena from brine evaporation arrested in porous bricks, causing efflorescence, i.e. salt aggregation on the surface where vapor leaves the medium, to clogging of reservoir rocks via salt precipitation when carbon dioxide is injected for geological storage. During the process of drying, the permeability and porosity of the medium may change due to the solute accumulation as a function of the particle concentration, in turn affecting the evaporation rate and the dynamics of the fluid flow imposed by it. To examine the dynamics of these coupled quantities, we develop a multiphase model of the particulate flow of a saline suspension in a porous medium, induced by evaporation. We further provide dimensional arguments as to how the salt concentration and the resulting change in permeability determine the transition between efflorescence and salt precipitation in the bulk. This research was supported by the Air Force Office of Scientific Research (AFOSR) under Award FA9550-09-1-0669-DOD35CAP and the Kavli Institute for Bionano Science and Technology at Harvard University.
Simulations on porous media with nanofluids-initial study
Zeidan, D.; Alnaief, M.; Saghir, M. Ziad; Touma, R.
2016-06-01
Numerical simulations of natural convection heat and mass transfer in a square cavity using Comsol Multiphysics 5.0 software are presented. The effective thermal conductivity of nanofluid in porous media is computed using glass beads as porous media. It is observed that the heat and mass transfer rate increases with the increase of temperature variation as well as nanoparticle volume concentration.
Sophia Haussener; Aldo Steinfeld
2012-01-01
High-resolution X-ray computed tomography is employed to obtain the exact 3D geometrical configuration of porous anisotropic ceria applied in solar-driven thermochemical cycles for splitting H2O and CO2. The tomography data are, in turn, used in direct pore-level numerical simulations for determining the morphological and effective heat/mass transport properties of porous ceria, namely: porosity, specific surface area, pore size distribution, extinction coefficient, thermal conductivity, conv...
Gaussian beam diffraction in weakly anisotropic inhomogeneous media
Energy Technology Data Exchange (ETDEWEB)
Kravtsov, Yu.A., E-mail: kravtsov@am.szczecin.p [Institute of Physics, Maritime University of Szczecin, Szczecin 70-500 (Poland); Space Research Institute, Russian Academy of Science, Moscow 117 997 (Russian Federation); Berczynski, P., E-mail: pawel.berczynski@ps.p [Institute of Physics, West Pomeranian University of Technology, Szczecin 70-310 (Poland); Bieg, B., E-mail: b.bieg@am.szczecin.p [Institute of Physics, Maritime University of Szczecin, Szczecin 70-500 (Poland)
2009-08-10
Combination of quasi-isotropic approximation (QIA) of geometric optics with paraxial complex geometric optics (PCGO) is suggested, which allows describing both diffraction and polarization evolution of Gaussian electromagnetic beams in weakly anisotropic inhomogeneous media. Combination QIA/PCGO reduces Maxwell equations to the system of the ordinary differential equations of the first order and radically simplifies solution of various problems, related to microwave plasma diagnostics, including plasma polarimetry, interferometry and refractometry in thermonuclear reactors. Efficiency of the method is demonstrated by the example of electromagnetic beam diffraction in a linear layer of magnetized plasma with parameters, modeling tokamak plasma in the project ITER.
Gaussian beam diffraction in weakly anisotropic inhomogeneous media
International Nuclear Information System (INIS)
Combination of quasi-isotropic approximation (QIA) of geometric optics with paraxial complex geometric optics (PCGO) is suggested, which allows describing both diffraction and polarization evolution of Gaussian electromagnetic beams in weakly anisotropic inhomogeneous media. Combination QIA/PCGO reduces Maxwell equations to the system of the ordinary differential equations of the first order and radically simplifies solution of various problems, related to microwave plasma diagnostics, including plasma polarimetry, interferometry and refractometry in thermonuclear reactors. Efficiency of the method is demonstrated by the example of electromagnetic beam diffraction in a linear layer of magnetized plasma with parameters, modeling tokamak plasma in the project ITER.
Gaussian beam diffraction in weakly anisotropic inhomogeneous media
Kravtsov, Yu. A.; Berczynski, P.; Bieg, B.
2009-08-01
Combination of quasi-isotropic approximation (QIA) of geometric optics with paraxial complex geometric optics (PCGO) is suggested, which allows describing both diffraction and polarization evolution of Gaussian electromagnetic beams in weakly anisotropic inhomogeneous media. Combination QIA/PCGO reduces Maxwell equations to the system of the ordinary differential equations of the first order and radically simplifies solution of various problems, related to microwave plasma diagnostics, including plasma polarimetry, interferometry and refractometry in thermonuclear reactors. Efficiency of the method is demonstrated by the example of electromagnetic beam diffraction in a linear layer of magnetized plasma with parameters, modeling tokamak plasma in the project ITER.
ON FREE WAVE PROPAGATION IN ANISOTROPIC LAYERED MEDIA
Institute of Scientific and Technical Information of China (English)
Yongqiang Guo; Weiqiu Chen
2008-01-01
The method of reverberation-ray matrix (MRRM) is extended and modified for the analysis of free wave propagation in anisotropic layered elastic media. A general, numerically stable formulation is established within the state space framework. The compatibility of physical variables in local dual coordinates gives the phase relation, from which exponentially growing functions are excluded. The interface and boundary conditions lead to the scattering relation,which avoids matrix inversion operation. Numerical examples are given to show the high accuracy of the present MRRM.
Review of enhanced vapor diffusion in porous media
International Nuclear Information System (INIS)
Vapor diffusion in porous media in the presence of its own liquid has often been treated similar to gas diffusion. The gas diffusion rate in porous media is much lower than in free space due to the presence of the porous medium and any liquid present. However, enhanced vapor diffusion has also been postulated such that the diffusion rate may approach free-space values. Existing data and models for enhanced vapor diffusion, including those in TOUGH2, are reviewed in this paper
Propagation of plane waves in poroviscoelastic anisotropic media
Institute of Scientific and Technical Information of China (English)
A.K.Vashishth,M.D.Sharma
2008-01-01
This study discusses wave propagation in perhaps the most general model of a poroelastic medium.The medium is considered as a viscoelastic,anisotropic and porous solid frame such that its pores of anisotropic permeability are filled with a viscous fluid.The anisotropy considered is of general type,and the attenuating waves in the medium are treated as the inhomogeneous waves.The complex slowness vector is resolved to define the phase velocity,homogeneous attenuation,inhomogeneous attenuation,and angle of attenuation for each of the four attenuating waves in the medium.A non-dimensional parameter measures the deviation of an inhomogeneous wave from its homogeneous version.An numerical model of a North-Sea sandstone is used to analyze the effects of the propagation direction,inhomogeneity parameter,frequency regime,anisotropy symmetry,anelasticity of the frame,and viscosity of the pore-fluid on the propagation characteristics of waves in such a medium.
Percolation theory for flow in porous media
Hunt, Allen; Ghanbarian, Behzad
2014-01-01
This monograph presents, for the first time, a unified and comprehensive introduction to some of the basic transport properties of porous media, such as electrical and hydraulic conductivity, air permeability and diffusion. The approach is based on critical path analysis and the scaling of transport properties, which are individually described as functions of saturation. At the same time, the book supplies a tutorial on percolation theory for hydrologists, providing them with the tools for solving actual problems. In turn, a separate chapter serves to introduce physicists to some of the language and complications of groundwater hydrology necessary for successful modeling. The end-of-chapter problems often indicate open questions, which young researchers entering the field can readily start working on. This significantly revised and expanded third edition includes in particular two new chapters: one on advanced fractal-based models, and one devoted to the discussion of various open issues such as the role of d...
On a singular incompressible porous media equation
Friedlander, Susan; Sun, Weiran; Vicol, Vlad
2012-01-01
In this paper we study a singularly modified version of the incompressible porous media equation. We investigate the implications for the local well-posedness of the equations by modifying, with a fractional derivative, the constitutive relation between the scalar density and the convecting divergence free velocity vector. Our analysis is motivated by recent work \\cite{CCCGW} where it is shown that for the surface quasi-geostrophic equation such a singular modification of the constitutive law for the velocity, quite surprisingly still yields a locally well-posed problem. In contrast, for the singular active scalar equation discussed in this paper, local well-posedness does not hold for smooth solutions, but it does hold for certain weak solutions.
Shock Electrodeposition in Charged Porous Media
Han, Ji-Hyung
2015-01-01
It is shown that surface conduction in porous media can drastically alter the stability and morphology of electrodeposition at high rates, above the diffusion-limited current. Copper electrodeposits are visualized by scanning electron microscopy and energy dispersive spectroscopy in cellulose nitrate membranes, whose pores are coated with positive or negative charged polymers. Above the limiting current, surface conduction inhibits growth in the positive membrane and produces irregular dendrites, while it enhances growth and suppresses dendrites behind a deionization shock in the negative membrane. The discovery of uniform growth contradicts quasi-steady leaky membrane models, which are in the same universality class as unstable Laplacian growth, and indicates the importance of transient electro-diffusion or electro-osmotic dispersion. Shock electrodeposition could be exploited for high-rate recharging of metal batteries or manufacturing of metal matrix composite coatings.
Mechanics of fluids in porous media
Bear, Jacob; Corapcioglu, M. Yavuz
Transport of quantities such as mass component of a phase and/or heat occurs in fields as diversified as petroleum reservoir engineering, groundwater hydraulics, soil mechanics, industrial filtration, water purification, wastewater treatment, soil drainage and irrigation, and geothermal energy production. In all these areas, scientists, engineers, and planners make use of mathematical models; these models describe the relevant transport processes that occur within controlled porous medium domains and enable forecasting of the future behavior of these domains in response to planned activities. The mathematical models, in turn, are based on the understanding of phenomena, often within the void space, and on theories that relate these phenomena to measurable quantities.Because of the pressing needs in areas of practical interest such as the development of groundwater energy storage and geothermal energy production, a vast amount of research in all these fields has contributed, especially in the last two decades, to our understanding and ability to describe transport phenomena in porous media. In recent years these research efforts have been significantly accelerated, attracting scientists from many disciplines. The practical needs of solving boundary value problems in heterogeneous domains, irregular boundaries, coupled phenomena and multiple dependent variables led to the development of a variety of powerful numerical techniques. The realization that fields are highly heterogeneous and that the degree of heterogeneity depends on the scale of the problem led to the introduction of stochastic concepts as an additional tool for the description of phenomena.
Minor Losses During Air Flow into Granular Porous Media
DEFF Research Database (Denmark)
Poulsen, Tjalfe; Minelgaite, Greta; Bentzen, Thomas Ruby;
2013-01-01
Pressure gradients during uniform fluid flow in porous media are traditionally assumed to be linear. Thus pressure loss across a sample of porous medium is assumed directly proportional to the thickness of the sample. In this study, measurements of pressure gradients inside coarse granular (2 – 18...... mm particle size) porous media during steady gas flow were carried out. The results showed that pressure variation with distance in the porous media were nonlinear near the inlet (where pressure gradients were higher) but became linear at greater distances (with a lower gradient). This indicates...... that pressure loss in porous media consists of two components: (1) a linear pressure gradient and (2) an initial pressure loss near the inlet. This initial pressure loss is also known from hydraulics in tubes as a minor loss and is associated with abrupt changes in the flow field such as narrowings and bends...
Elastodynamic analysis of anisotropic liquid-saturated porous medium due to mechanical sources
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
Elastodynamlc analysis of an anisotropic liquid-saturated porous medium is made to study a deformation problem of a transversely isotropic liquid-saturated porous medium due to mechanical sources. Certain physical problems are of the nature, in which the deformation takes place only in one direction, e.g., the problem relating to deformed structures and columns. In soil mechanics, an assumption of only vertical subsidence is often invoked and this leads to the one dimensional model of poroelasticity. By considering a model of one-dimensional deformation of the anisotropic liquid-saturated porous medium, variations in disturbances are observed with reference to time and distance.The distributions of displacements and stresses are affected due to the anisotropy of the medium, and also due to the type of sources causing the disturbances.
A Fractal Model for Capillary Pressure of Porous Media
Directory of Open Access Journals (Sweden)
Boqi Xiao
2013-06-01
Full Text Available Capillary pressure is a basic parameter in the study of the behavior of porous media containing two or more immiscible fluid phases. In this study, the capillary pressure of porous media is predicted based on based on fractal property of pore in porous media. The formula of calculating the capillary pressure of porous media is given. The capillary pressure of porous media is expressed as a function of porosity, fractal dimension of pore and saturation. Based on the parametric effect analysis, we conclude that the capillary pressure of porous media is negatively correlated with the porosity and saturation. Besides, it is shown that the capillary pressure of unsaturated porous media decreases with the increase of saturation. No additional empirical constant is introduced. This model contains less empirical constants than the conventional correlations. The model predictions are compared with the existing experimental data and good agreement between the model predictions and experimental data is found. The validity of the present fractal model is thus verified.
Experimental investigation of transverse mixing in porous media under helical flow conditions
Ye, Yu; Chiogna, Gabriele; Cirpka, Olaf A.; Grathwohl, Peter; Rolle, Massimo
2016-07-01
Plume dilution and transverse mixing can be considerably enhanced by helical flow occurring in three-dimensional heterogeneous anisotropic porous media. In this study, we perform tracer experiments in a fully three-dimensional flow-through chamber to investigate the effects of helical flow on plume spiraling and deformation, as well as on its dilution. Porous media were packed in angled stripes of materials with different grain sizes to create blocks with macroscopically anisotropic hydraulic conductivity, which caused helical flows. Steady-state transport experiments were carried out by continuously injecting dye tracers at different inlet ports. High-resolution measurements of concentration and flow rates were performed at 49 outlet ports. These measurements allowed quantifying the spreading and dilution of the solute plumes at the outlet cross section. Direct evidence of plume spiraling and visual proof of helical flow was obtained by freezing and slicing the porous media at different cross sections and observing the dye-tracer distribution. We simulated flow and transport to interpret our experimental observations and investigate the effects of helical flow on mixing-controlled reactive transport. The simulation results were evaluated using metrics of reactive mixing such as the critical dilution index and the length of continuously injected steady-state plumes. The results show considerable reaction enhancement, quantified by the remarkable decrease of reactive plume lengths (up to four times) in helical flows compared to analogous scenarios in uniform flows.
Chiogna, Gabriele; Herrera, Paulo
2015-04-01
Several studies have demonstrated how plume deformation induced by flow heterogeneity in porous media can enhance mixing of reactants. This enhancement can have important impact on mixing controlled reactions such a biodegradation of plumes of organic compounds. On the other hand, recent studies have indicated the possibility of observing complex flow topology on groundwater flow that occurs in anisotropic yet homogenous porous media. Moreover, it has been demonstrated that those complex flow topologies can also enhance solute mixing. We study the effect of medium anisotropy on reactive solute transport for the case of a chemical reactor composed of two homogeneous anisotropic layers. We simulate different injection strategies for different chemical reactions that involve two reactants. We demonstrate the effect of the medium anisotropy by analyzing the results of the simulations and identify best strategies for the operation and design of the system to maximize reaction rates. These findings could have potential application in the design of new remediation systems for contaminated groundwater, chemical reactors and other engineering problems that involve flow through porous media.
Nanoparticle tracers in calcium carbonate porous media
Li, Yan Vivian
2014-07-15
Tracers are perhaps the most direct way of diagnosing subsurface fluid flow pathways for ground water decontamination and for natural gas and oil production. Nanoparticle tracers could be particularly effective because they do not diffuse away from the fractures or channels where flow occurs and thus take much less time to travel between two points. In combination with a chemical tracer they can measure the degree of flow concentration. A prerequisite for tracer applications is that the particles are not retained in the porous media as the result of aggregation or sticking to mineral surfaces. By screening eight nanoparticles (3-100 nm in diameter) for retention when passed through calcium carbonate packed laboratory columns in artificial oil field brine solutions of variable ionic strength we show that the nanoparticles with the least retention are 3 nm in diameter, nearly uncharged, and decorated with highly hydrophilic polymeric ligands. The details of these column experiments and the tri-modal distribution of zeta potential of the calcite sand particles in the brine used in our tests suggests that parts of the calcite surface have positive zeta potential and the retention of negatively charged nanoparticles occurs at these sites. Only neutral nanoparticles are immune to at least some retention. © 2014 Springer Science+Business Media.
Experimental Investigation on Heat Transfer Enhancement in Composite Porous Media
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
The method of composite porous media with mini-longitudinal channels at the surface and with beads packing between plates was put foward to improve the integated performance of flow and heat transfer in porous media. The experimental results in the corresponding porous media were reported and analyzed. The experiments indicate that with proper matching of the particle diameter dp, the mini-channel width w, the channel depth d and the distance between plates δr the heat transfer in the composite porois media is enhanced and flow resistence reduced compared with those of no mini-longitudinal channels at the surface. So this is an effective method to improve the integrated performance of flow and heat transfer in porous media.
Institute of Scientific and Technical Information of China (English)
刘洋; 魏修成
2003-01-01
Based on Biot theory of two-phase anisotropic media and Hamilton theory about dynamic problem, finite elementequations of elastic wave propagation in two-phase anisotropic media are derived in this paper. Numerical solutionof finite element equations is given. Finally, properties of elastic wave propagation are observed and analyzedthrough FEM modeling.
Fractal Analysis of Stress Sensitivity of Permeability in Porous Media
Tan, Xiao-Hua; Li, Xiao-Ping; Liu, Jian-Yi; Zhang, Lie-Hui; Cai, Jianchao
2015-12-01
A permeability model for porous media considering the stress sensitivity is derived based on mechanics of materials and the fractal characteristics of solid cluster size distribution. The permeability of porous media considering the stress sensitivity is related to solid cluster fractal dimension, solid cluster fractal tortuosity dimension, solid cluster minimum diameter and solid cluster maximum diameter, Young's modulus, Poisson's ratio, as well as power index. Every parameter has clear physical meaning without the use of empirical constants. The model predictions of permeability show good agreement with those obtained by the available experimental expression. The proposed model may be conducible to a better understanding of the mechanism for flow in elastic porous media.
Foam Transport in Porous Media - A Review
Energy Technology Data Exchange (ETDEWEB)
Zhang, Z. F.; Freedman, Vicky L.; Zhong, Lirong
2009-11-11
Amendment solutions with or without surfactants have been used to remove contaminants from soil. However, it has drawbacks such that the amendment solution often mobilizes the plume, and its movement is controlled by gravity and preferential flow paths. Foam is an emulsion-like, two-phase system in which gas cells are dispersed in a liquid and separated by thin liquid films called lamellae. Potential advantages of using foams in sub-surface remediation include providing better control on the volume of fluids injected, uniformity of contact, and the ability to contain the migration of contaminant laden liquids. It is expected that foam can serve as a carrier of amendments for vadose zone remediation, e.g., at the Hanford Site. As part of the U.S. Department of Energy’s EM-20 program, a numerical simulation capability will be added to the Subsurface Transport Over Multiple Phases (STOMP) flow simulator. The primary purpose of this document is to review the modeling approaches of foam transport in porous media. However, as an aid to understanding the simulation approaches, some experiments under unsaturated conditions and the processes of foam transport are also reviewed. Foam may be formed when the surfactant concentration is above the critical micelle concentration. There are two main types of foams – the ball foam (microfoam) and the polyhedral foam. The characteristics of bulk foam are described by the properties such as foam quality, texture, stability, density, surface tension, disjoining pressure, etc. Foam has been used to flush contaminants such as metals, organics, and nonaqueous phase liquids from unsaturated soil. Ball foam, or colloidal gas aphrons, reportedly have been used for soil flushing in contaminated site remediation and was found to be more efficient than surfactant solutions on the basis of weight of contaminant removed per gram of surfactant. Experiments also indicate that the polyhedral foam can be used to enhance soil remediation. The
Modeling approaches to natural convection in porous media
Su, Yan
2015-01-01
This book provides an overview of the field of flow and heat transfer in porous medium and focuses on presentation of a generalized approach to predict drag and convective heat transfer within porous medium of arbitrary microscopic geometry, including reticulated foams and packed beds. Practical numerical methods to solve natural convection problems in porous media will be presented with illustrative applications for filtrations, thermal storage and solar receivers.
Principle of effective stress in variably saturated porous media (editorial)
Lu, N.; Khalili, N.; Nikooee, E.; Hassanizadeh, S.M.
2014-01-01
This editorial highlights the motivations, historic perspectives, future prospects, and some details of the technical contents of the special issue on Principle of Effective Stress in Variably Saturated Porous Media.
A Particle Resistance Model for Flow through Porous Media
International Nuclear Information System (INIS)
A particle model for resistance of flow in isotropic porous media is developed based on the fractal geometry theory and on the drag force flowing around sphere. The proposed model is expressed as a function of porosity, fluid property, particle size, fluid velocity (or Reynolds number) and fractal characters Df of particles in porous media. The model predictions are in good agreement with the experimental data. The validity of the proposed model is thus verified. (fundamental areas of phenomenology (including applications))
A Particle Resistance Model for Flow through Porous Media
Institute of Scientific and Technical Information of China (English)
WU Jin-Sui; YIN Shang-Xian; ZHAO Dong-Yu
2009-01-01
A particle model for resistance of flow in isotropic porous media is developed based on the fractal geometry theory and on the drag force flowing around sphere.The proposed model is expressed as a function of porosity,fluid property,particle size,fluid velocity (or Reynolds number) and fractal characters Df of particles in porous media.The model predictions are in good agreement with the experimental data.The validity of the proposed model is thus verified.
Discrete Morse flow for Ricci flow and Porous Media equation
Ma, Li
2012-01-01
In this paper, we study the discrete Morse flow for the Ricci flow on football, which is the 2-sphere with removed north and south poles and with the metric $g_0$ of constant scalar curvature, and and for Porous media equation on a bounded regular domain in the plane. We show that with a suitable assumption about $g(0)$ we have a weak approximated discrete Morse flow for the approximated Ricci flow and Porous media equation on any time intervals.
Characterization of an impinging jet into porous media
Wang, Cong; Alhani, Salwan; Gharib, Morteza
2015-11-01
In this work, characteristic behavior of a liquid jet into porous hydrophobic / hydrophilic particle media is investigated. In porous media, the capillary effect becomes significant, especially when the jet Reynolds Number is low. To analyze the cavity creation phenomena, the effect of jet's diameter, speed and acceleration as well as particles' size are carefully studied. Such knowledge of fluid behavior will provide guidance for medicine injection process. This work is supported by Caltech GALCIT STEM program.
Impact of space-time mesh adaptation on solute transport modeling in porous media
Esfandiar, Bahman; Porta, Giovanni; Perotto, Simona; Guadagnini, Alberto
2015-02-01
We implement a space-time grid adaptation procedure to efficiently improve the accuracy of numerical simulations of solute transport in porous media in the context of model parameter estimation. We focus on the Advection Dispersion Equation (ADE) for the interpretation of nonreactive transport experiments in laboratory-scale heterogeneous porous media. When compared to a numerical approximation based on a fixed space-time discretization, our approach is grounded on a joint automatic selection of the spatial grid and the time step to capture the main (space-time) system dynamics. Spatial mesh adaptation is driven by an anisotropic recovery-based error estimator which enables us to properly select the size, shape, and orientation of the mesh elements. Adaptation of the time step is performed through an ad hoc local reconstruction of the temporal derivative of the solution via a recovery-based approach. The impact of the proposed adaptation strategy on the ability to provide reliable estimates of the key parameters of an ADE model is assessed on the basis of experimental solute breakthrough data measured following tracer injection in a nonuniform porous system. Model calibration is performed in a Maximum Likelihood (ML) framework upon relying on the representation of the ADE solution through a generalized Polynomial Chaos Expansion (gPCE). Our results show that the proposed anisotropic space-time grid adaptation leads to ML parameter estimates and to model results of markedly improved quality when compared to classical inversion approaches based on a uniform space-time discretization.
Dual Transport Process for Targeted Delivery in Porous Media
Deng, W.; Fan, J.
2015-12-01
The targeted delivery in porous media is a promising technology to encapsulate the solute (i.e., the cargo) in colloid-like microcapsules (i.e., the carriers), transport the microcapsules in the targeted location in porous media, and then release the solute. While extensive literatures and applications about the drug delivery in human and animal bodies exist, the targeted delivery using similar delivery carriers in subsurface porous media is not well understood. The dual transport process study is an explorative study for the targeted delivery in porous media. While the colloid transport is dominated by the advection process and the solute transport is dominated by the advection-dispersion, the dual transport process is the process with the first step of carrier transport, which is dominated by advection, and then after the release of cargo, the transport of cargo is dominated by advection-dispersion. By applying the random walk particle tracking (RWPT) approach, we investigate how the carriers transport in porous media and how the cargo release mechanisms affect the cargo distribution for the targeted delivery in various patterns of porous media. The RWPT numerical model will be verified against the experimental results of dual transport process in packed-disk 2D micromodels. The understanding of the mechanism of dual transport process is crucial to achieve the potential applications of targeted delivery in improved oil and gas recovery, CO2 sequestration, environmental remediation, and soil biomediation.
Experimental investigation of transverse mixing in porous media under helical flow conditions
DEFF Research Database (Denmark)
Ye, Yu; Chiogna, Gabriele; Cirpka, Olaf A.;
2016-01-01
transport. The simulation results were evaluated using metrics of reactive mixing such as the critical dilution index and the length of continuously injected steady-state plumes. The results show considerable reaction enhancement, quantified by the remarkable decrease of reactive plume lengths (up to four...... spiraling and deformation, as well as on its dilution. Porous media were packed in angled stripes of materials with different grain sizes to create blocks with macroscopically anisotropic hydraulic conductivity, which caused helical flows. Steady-state transport experiments were carried out by continuously...... times) in helical flows compared to analogous scenarios in uniform flows....
Evaporation Limited Radial Capillary Penetration in Porous Media.
Liu, Mingchao; Wu, Jian; Gan, Yixiang; Hanaor, Dorian A H; Chen, C Q
2016-09-27
The capillary penetration of fluids in thin porous layers is of fundamental interest in nature and various industrial applications. When capillary flows occur in porous media, the extent of penetration is known to increase with the square root of time following the Lucas-Washburn law. In practice, volatile liquid evaporates at the surface of porous media, which restricts penetration to a limited region. In this work, on the basis of Darcy's law and mass conservation, a general theoretical model is developed for the evaporation-limited radial capillary penetration in porous media. The presented model predicts that evaporation decreases the rate of fluid penetration and limits it to a critical radius. Furthermore, we construct a unified phase diagram that describes the limited penetration in an annular porous medium, in which the boundaries of outward and inward liquid are predicted quantitatively. It is expected that the proposed theoretical model will advance the understanding of penetration dynamics in porous media and facilitate the design of engineered porous architectures. PMID:27583455
Capillary thermomechanics in serially porous media, with implications for randomly porous media
Miller, Robert D.
Visions of a single mobile substance present as two rival phases more or less cleanly segregated by capillarity between rival strata of a serially porous medium (a ``discontinuum'') imply explicit testable equations for externally measured capillary thermo-osmotic pressures and capillary thermo-osmosis, with implications for thermomechanical consolidation, dilation, and cracking. Underlying equations assume fluid phases governed by the laws of surface tension and viscous flow, moderated by an appropriate form of the Clapeyron equation. Derived phenomenological coefficients in macroscopic equations for steady coupled transports of mass and heat include only path-length-weighted fluid and heat conductances for rival domains and the heat of phase transformation. Expressions emphasize the phase-specific nature of Onsager's reciprocity principle and apply to serial media held within permeameters set up for measuring either ``isothermal'' or ``adiabatic'' mass transport or held within sealed containers intended for measurements of ``thermal conductivities.'' Results clarify unmet challenges facing modelers of similar processes and attributes in randomly porous media.
Wang, Ding; Wang, Liji; Ding, Pinbo
2016-08-01
An illustrative theory is developed to analyze the acoustic wave propagation characteristics in the porous media with anisotropic permeability. We focus here on the role of fracture permeability in the unconsolidated porous media, looking in particular at the compressional P-wave phase velocity and attenuation. Two fluid pressure equilibration characteristic time factors are defined, which are corresponding to crack-pore system and crack-crack system, respectively. The theoretical results show that the dispersion and attenuation characteristics of acoustic wave are affected by porous matrix and fracture permeability simultaneously. Due to the fluid exchange that takes place between fractures and pores dominantly, the influence of the fracture connectivity on the wave propagation is very weak when the permeability of background medium is relatively high. However, correlation between wave propagation and fracture permeability is significant when the matrix permeability at a low level. A second attenuation peak occurs for the fluid flow within fractures in high-frequency region for more and more higher fracture permeability. The exact analytical solutions that are compared to numerical forward modeling of wave propagation in fractured media allow us to verify the correctness of the new model. If there exists another approach for obtaining the connectivity information of background media, we can use this model to analyze qualitatively the permeability of fractures or afford an indicator of in-situ permeability changes in a oil reservoir, for example, fracturing operations. PMID:27259119
The Kinematics and Field Equations for Porous Media
Institute of Scientific and Technical Information of China (English)
无
1999-01-01
With a porous medium regarded as an immiscible mixture of multiphase and each phase as a miscible mixture of multi-constituent, a systematical research on the kinematics and field equations for porous media is carried out from the point of view of mixture theory. It is shown that the motion of each phase is the mathematical average of the motions of all constituents in the phase, and that the motion of porous media may be described as the motion of the skeleton and the relative motion of each phase with respect to the skeleton. The influence of mass exchange between different constituents in each phase and the influence of mass exchange of same constituent between different phases in porous media are considered in field equations which are self-consistent in theory. All the field equations in the references are special cases of the equations proposed in this paper.
Porous media heat transfer for injection molding
Energy Technology Data Exchange (ETDEWEB)
Beer, Neil Reginald
2016-05-31
The cooling of injection molded plastic is targeted. Coolant flows into a porous medium disposed within an injection molding component via a porous medium inlet. The porous medium is thermally coupled to a mold cavity configured to receive injected liquid plastic. The porous medium beneficially allows for an increased rate of heat transfer from the injected liquid plastic to the coolant and provides additional structural support over a hollow cooling well. When the temperature of the injected liquid plastic falls below a solidifying temperature threshold, the molded component is ejected and collected.
Transport of human adenoviruses in porous media
Kokkinos, Petros; Syngouna, Vasiliki I.; Tselepi, Maria A.; Bellou, Maria; Chrysikopoulos, Constantinos V.; Vantarakis, Apostolos
2015-04-01
Groundwater may be contaminated with infective human enteric viruses from various wastewater discharges, sanitary landfills, septic tanks, agricultural practices, and artificial groundwater recharge. Coliphages have been widely used as surrogates of enteric viruses, because they share many fundamental properties and features. Although a large number of studies focusing on various factors (i.e. pore water solution chemistry, fluid velocity, moisture content, temperature, and grain size) that affect biocolloid (bacteria, viruses) transport have been published over the past two decades, little attention has been given toward human adenoviruses (hAdVs). The main objective of this study was to evaluate the effect of pore water velocity on hAdV transport in water saturated laboratory-scale columns packed with glass beads. The effects of pore water velocity on virus transport and retention in porous media was examined at three pore water velocities (0.39, 0.75, and 1.22 cm/min). The results indicated that all estimated average mass recovery values for hAdV were lower than those of coliphages, which were previously reported in the literature by others for experiments conducted under similar experimental conditions. However, no obvious relationship between hAdV mass recovery and water velocity could be established from the experimental results. The collision efficiencies were quantified using the classical colloid filtration theory. Average collision efficiency, α, values decreased with decreasing flow rate, Q, and pore water velocity, U, but no significant effect of U on α was observed. Furthermore, the surface properties of viruses and glass beads were used to construct classical DLVO potential energy profiles. The results revealed that the experimental conditions of this study were unfavorable to deposition and that no aggregation between virus particles is expected to occur. A thorough understanding of the key processes governing virus transport is pivotal for public
Van der Waals interaction torque and force between dielectrically anisotropic layered media
Lu, Bing-Sui
2016-01-01
We analyse the van der Waals interaction for a pair of dielectrically anisotropic plane-layered media interacting across a dielectrically isotropic medium. We investigate the van der Waals torque and force for the following cases: (i) a pair of single anisotropic layers, (ii) a single anisotropic layer interacting with a multilayered slab consisting of alternating anisotropic and isotropic layers, and (iii) a pair of multilayered slabs each consisting of alternating anisotropic and isotropic layers, looking at the cases where the optical axes lie parallel and/or perpendicular to the plane of the layers. For the first case, the optical axes of the oppositely facing anisotropic layers of the two interacting slabs generally have an angular mismatch, and within each multilayered slab the optical axes may either be the same, or undergo constant angular increments across the anisotropic layers. In particular, we examine how the behaviors of the van der Waals torque and force can be "tuned" by adjusting the layer th...
Energy Technology Data Exchange (ETDEWEB)
Laha, P., E-mail: plaha@vub.ac.be; Terryn, H.; Ustarroz, J., E-mail: justarro@vub.ac.be [Research Group Electrochemical and Surface Engineering (SURF), Vrije Universiteit Brussel, Pleinlaan 2, 1050 Elsene, Brussels (Belgium); Nazarkin, M. Y., E-mail: mikleo@mail.ru; Gavrilov, S. A. [Department of Materials of Functional Electronics (MFE), National Research University of Electronic Technology, Bld. 5, Pas. 4806, Zelenograd, Moscow 124498 (Russian Federation); Volkova, A. V.; Simunin, M. M. [Department of Quantum Physics and Nanoelectronics (QPN), National Research University of Electronic Technology, Bld. 5, Pas. 4806, Zelenograd, Moscow 124498 (Russian Federation)
2015-03-09
ZnO films have increasingly been in the spotlight due to their largely varied electro-physical and optical properties. For several applications, porous anisotropic nanocrystalline layers are especially interesting. To study the growth kinetics of such films during different fabrication processes, a powerful non-destructive in-situ technique is required. In this work, both ex-situ and in-situ spectroscopic ellipsometry are used along with advanced modelling techniques that are able to take both the anisotropy and the porosity of the films into account. Scanning electron microscopy, along with nitrogen absorption methods for measuring porosity, validated the ellipsometric data and proposed model. The film, grown by chemical bath deposition, was monitored from around 700 to 1800 nm in thickness. This same principle can now be used to monitor any other porous and/or anisotropic structure in an effective in-situ manner, e.g., growth of porous anodic aluminium oxides, nano-porous silica films, etc.
Nuclear magnetic relaxation of liquids in porous media
International Nuclear Information System (INIS)
Nuclear magnetic relaxation is useful for probing physical and chemical properties of liquids in porous media. Examples are given on high surface area porous materials including calibrated porous silica glasses, granular packings, plaster pastes, cement-based materials and natural porous materials, such as sandstone and carbonate rocks. Here, we outline our recent NMR relaxation work for these very different porous materials. For instance, low field NMR relaxation of water in calibrated granular packings leads to striking different pore-size dependencies of the relaxation times T1 and T2 when changing the amount of surface paramagnetic impurities. This allows separation of the diffusion and surface limited regimes of relaxation in these macroporous media. The magnetic field dependence of the nuclear spin-lattice relaxation rate 1/T1(ω0) is also a rich source of dynamical information for characterizing the molecular dynamics of liquids in porous media. This allows a continuous characterization of the evolving microstructure of various cementitious materials. Our recent applications of two-dimensional (2D) T1-T2 and T2-z-store-T2 correlation experiments have evidenced the water exchange in connected micropores of cement pastes. The direct probing of water adsorption time on a solid surface gives access to an original characterization of the surface nano-wettability of porous plaster pastes. We show that such a parameter depends directly on the physical chemistry of the pore surfaces. Lastly, we outline our recent measurements of wettability in oil/brine/reservoir carbonate rocks.
A pore scale study on turbulent combustion in porous media
Jouybari, N. F.; Maerefat, M.; Nimvari, M. E.
2016-02-01
This paper presents pore scale simulation of turbulent combustion of air/methane mixture in porous media to investigate the effects of multidimensionality and turbulence on the flame within the pores of porous media. In order to investigate combustion in the pores of porous medium, a simple but often used porous medium consisting of a staggered arrangement of square cylinders is considered in the present study. Results of turbulent kinetic energy, turbulent viscosity ratio, temperature, flame speed, convective heat transfer and thermal conductivity are presented and compared for laminar and turbulent simulations. It is shown that the turbulent kinetic energy increases from the inlet of burner, because of turbulence created by the solid matrix with a sudden jump or reduction at the flame front due to increase in temperature and velocity. Also, the pore scale simulation revealed that the laminarization of flow occurs after flame front in the combustion zone and turbulence effects are important mainly in the preheat zone. It is shown that turbulence enhances the diffusion processes in the preheat zone, but it is not enough to affect the maximum flame speed, temperature distribution and convective heat transfer in the porous burner. The dimensionless parameters associated with the Borghi-Peters diagram of turbulent combustion have been analyzed for the case of combustion in porous media and it is found that the combustion in the porous burner considered in the present study concerns the range of well stirred reactor very close to the laminar flame region.
Reptation of a semiflexible polymer through porous media
Nam, Gimoon; Johner, Albert; Lee, Nam-Kyung
2010-07-01
We study the motion of a single stiff semiflexible filament of length S through an array of topological obstacles. By means of scaling arguments and two-dimensional computer simulations, we show that the stiff chain kinetics follows the reptation picture, albeit with kinetic exponents (for the central monomer) different from those for flexible chain reptation. At early times when topological constraints are irrelevant, the chain kinetics is the anisotropic dynamics of a free filament. After the entanglement time τe transverse modes are equilibrated under the topological constraints, but the chain is not yet correlated over its whole length. During the relaxation of longitudinal modes, both the longitudinal fluctuation of the central monomer and the longitudinal correlation length grow as ˜√t . After time τr˜S2 chain ends are correlated, the chain then diffuses globally along the tube and tube renewal takes place. In the reptation regime, the longitudinal fluctuation of the central monomer grows like ˜t1. The opening of the intermediate ˜√t regime, absent for a free filament, is a signature of the reptation process. Although the underlying physics is quite different, the intermediate regime is reminiscent of the internal Rouse mode relaxation found for reptating flexible chains. In most cases asymptotic power laws from scaling could be complemented by prefactors calculated analytically. Our results are supported by two-dimensional Langevin simulations with fixed obstacles via evaluation of the mean squared displacement of the central monomer. The scaling theory can be extended to long semiflexible polymers adopting random-walk equilibrium configurations and should also apply in three dimensions for porous media with pore diameter smaller than the persistence length of the filament.
Tritium transport in lithium ceramics porous media
Energy Technology Data Exchange (ETDEWEB)
Tam, S.W.; Ambrose, V.
1991-12-31
A random network model has been utilized to analyze the problem of tritium percolation through porous Li ceramic breeders. Local transport in each pore channel is described by a set of convection-diffusion-reaction equations. Long range transport is described by a matrix technique. The heterogeneous structure of the porous medium is accounted for via Monte Carlo methods. The model was then applied to an analysis of the relative contribution of diffusion and convective flow to tritium transport in porous lithium ceramics. 15 refs., 4 figs.
Tritium transport in lithium ceramics porous media
Energy Technology Data Exchange (ETDEWEB)
Tam, S.W.; Ambrose, V.
1991-01-01
A random network model has been utilized to analyze the problem of tritium percolation through porous Li ceramic breeders. Local transport in each pore channel is described by a set of convection-diffusion-reaction equations. Long range transport is described by a matrix technique. The heterogeneous structure of the porous medium is accounted for via Monte Carlo methods. The model was then applied to an analysis of the relative contribution of diffusion and convective flow to tritium transport in porous lithium ceramics. 15 refs., 4 figs.
SPH numerical simulation of fluid flow through a porous media
Klapp-Escribano, Jaime; Mayoral-Villa, Estela; Rodriguez-Meza, Mario Alberto; de La Cruz-Sanchez, Eduardo; di G Sigalotti, Leonardo; Inin-Abacus Collaboration; Ivic Collaboration
2013-11-01
We have tested an improved a method for 3D SPH simulations of fluid flow through a porous media using an implementation of this method with the Dual-Physics code. This improvement makes it possible to simulate many particles (of the order of several million) in reasonable computer times because its execution on GPUs processors makes it possible to reduce considerably the simulation cost for large systems. Modifications in the initial configuration have been implemented in order to simulate different arrays and geometries for the porous media. The basic tests were reproduced and the performance was analyzed. Our 3D simulations of fluid flow through a saturated homogeneous porous media shows a discharge velocity proportional to the hydraulic gradient reproducing Darcy's law at small body forces. The results are comparable with values obtained in previous work and published in the literature for simulations of flow through periodic porous media. Our simulations for a non saturated porous media produce adequate qualitative results showing that a non steady state is generated. The relaxation time for these systems were obtained. Work partially supported by Cinvestav-ABACUS, CONACyT grant EDOMEX-2011-C01-165873.
a Fractal Network Model for Fractured Porous Media
Xu, Peng; Li, Cuihong; Qiu, Shuxia; Sasmito, Agus Pulung
2016-04-01
The transport properties and mechanisms of fractured porous media are very important for oil and gas reservoir engineering, hydraulics, environmental science, chemical engineering, etc. In this paper, a fractal dual-porosity model is developed to estimate the equivalent hydraulic properties of fractured porous media, where a fractal tree-like network model is used to characterize the fracture system according to its fractal scaling laws and topological structures. The analytical expressions for the effective permeability of fracture system and fractured porous media, tortuosity, fracture density and fraction are derived. The proposed fractal model has been validated by comparisons with available experimental data and numerical simulation. It has been shown that fractal dimensions for fracture length and aperture have significant effect on the equivalent hydraulic properties of fractured porous media. The effective permeability of fracture system can be increased with the increase of fractal dimensions for fracture length and aperture, while it can be remarkably lowered by introducing tortuosity at large branching angle. Also, a scaling law between the fracture density and fractal dimension for fracture length has been found, where the scaling exponent depends on the fracture number. The present fractal dual-porosity model may shed light on the transport physics of fractured porous media and provide theoretical basis for oil and gas exploitation, underground water, nuclear waste disposal and geothermal energy extraction as well as chemical engineering, etc.
Asymptotics of the filtration problem for suspension in porous media
Directory of Open Access Journals (Sweden)
Kuzmina Ludmila Ivanovna
2015-01-01
Full Text Available The mechanical-geometric model of the suspension filtering in the porous media is considered. Suspended solid particles of the same size move with suspension flow through the porous media - a solid body with pores - channels of constant cross section. It is assumed that the particles pass freely through the pores of large diameter and are stuck at the inlet of pores that are smaller than the particle size. It is considered that one particle can clog only one small pore and vice versa. The particles stuck in the pores remain motionless and form a deposit. The concentrations of suspended and retained particles satisfy a quasilinear hyperbolic system of partial differential equations of the first order, obtained as a result of macro-averaging of micro-stochastic diffusion equations. Initially the porous media contains no particles and both concentrations are equal to zero; the suspension supplied to the porous media inlet has a constant concentration of suspended particles. The flow of particles moves in the porous media with a constant speed, before the wave front the concentrations of suspended and retained particles are zero. Assuming that the filtration coefficient is small we construct an asymptotic solution of the filtration problem over the concentration front. The terms of the asymptotic expansions satisfy linear partial differential equations of the first order and are determined successively in an explicit form. It is shown that in the simplest case the asymptotics found matches the known asymptotic expansion of the solution near the concentration front.
Characterization of porous media and refractory materials
Chen, Xin
Because of its unique advantages on energy savings and casting complex shapes, Lost Foam Casting (LFC) has been widely used as a replacement to the conventional techniques (sand and investment castings). In order to continuously improve the quality of the Lost Foam Casting process for reducing scrap rate and increasing energy savings, the US Department of Energy sponsored the present study to develop new characterization techniques for enhancing the understanding of the fundamental properties of the refractory materials used in the Lost Foam Casting process. In this study, new techniques are proposed to characterize the refractory materials' properties such as particle size, particle shape, rheological behavior, transport properties, microstructure, thickness, as well as packing properties. The microstructure information obtained from the proposed technique is found to be well correlated with the transport properties of the porous coating materials. A procedure using a three-dimensional computational fluid dynamics code is developed to simulate experimental gas flow data for solving complex boundary value problems. In this study, the effects of dilution and dispersion on the coating properties such as transport properties and microstructures are also investigated. Results show that the dilution and dispersion have opposing influences on the pore size and transport properties. In addition, this study also includes another part of the permeability system, the un-bonded granular materials used in the Lost Foam Casting process. A three-dimensional (3-D) computer program is developed to simulate the packing behavior of granular materials at a loose state using a "drop and roll" method. This study provides a systematic characterization of the LFC refractory coating slurries, dried refractory coating, and the granular media. This study also demonstrates the application of proposed characterization techniques for coating quality control using statistical process control
Acoustically driven filtration of particulate suspensions in porous media
Gupta, Sanjay
1997-12-01
A novel method of filtration of liquid suspensions containing micron to millimeter size particles has been developed. A resonant ultrasonic field, applied across a highly porous medium, has been used to trap fine particles inside the large pores (relative to the particle size) of the medium. Three types of porous media, unconsolidated bed of 3 mm glass beads, consolidated open pore aluminum mesh, and reticulated polyester polyurethane foam were investigated as the test media. Reasonable filtration efficiencies were achieved for model aqueous suspensions of 325 mesh polystyrene particles in all three porous media. The expected trends of filtration performance with respect to suspension flow rate, its concentration, and the acoustic field intensity were confirmed. The Filtration phenomena was found to be limited by non-physical saturation of porous media. At saturation, the particles collected inside the media were found to exhibit macroscopic vibrations which allows them to escape with the carrier fluid. The highly porous POLY foam (95% porosity) was found to be the best media for suspension studied in terms of the duration of particle retention and percentage filtration efficiencies. The aluminum mesh performed slightly poorer. The unconsolidated porous media collected the least amount of solids. A simple theoretical development based on particle trajectory around an infinitely long cylindrical fiber, in the presence of acoustic field, has been initiated. In principle, the new filtration method is similar to high gravity magnetic separation but the acoustic method has a wider scope due to inherent acoustic contrast present in most suspensions. The low pressure drop, ease of operation, amenability to large scale operation and reasonable filtration efficiency make the new method highly attractive and suitable for practical applications.
Impact of wettability correlations on multiphase flow through porous media
de la Lama, Marta S.; Brinkmann, Martin
2012-01-01
In the last decades, significant progress has been made in understanding the multiphase displacement through porous media with homogeneous wettability and its relation to the pore geometry. However, the role of wettability at the scale of the pore remains still little understood. In the present study the displacement of immiscible fluids through a two-dimensional porous medium is simulated by means of a mesoscopic particle approach. The substrate is described as an assembly of non-overlapping...
Modeling microbial processes in porous media
Murphy, Ellyn M.; Ginn, Timothy R.
The incorporation of microbial processes into reactive transport models has generally proceeded along two separate lines of investigation: (1) transport of bacteria as inert colloids in porous media, and (2) the biodegradation of dissolved contaminants by a stationary phase of bacteria. Research over the last decade has indicated that these processes are closely linked. This linkage may occur when a change in metabolic activity alters the attachment/detachment rates of bacteria to surfaces, either promoting or retarding bacterial transport in a groundwater-contaminant plume. Changes in metabolic activity, in turn, are controlled by the time of exposure of the microbes to electron acceptors/donor and other components affecting activity. Similarly, metabolic activity can affect the reversibility of attachment, depending on the residence time of active microbes. Thus, improvements in quantitative analysis of active subsurface biota necessitate direct linkages between substrate availability, metabolic activity, growth, and attachment/detachment rates. This linkage requires both a detailed understanding of the biological processes and robust quantitative representations of these processes that can be tested experimentally. This paper presents an overview of current approaches used to represent physicochemical and biological processes in porous media, along with new conceptual approaches that link metabolic activity with partitioning of the microorganism between the aqueous and solid phases. Résumé L'introduction des processus microbiologiques dans des modèles de transport réactif a généralement suivi deux voies différentes de recherches: (1) le transport de bactéries sous forme de colloïdes inertes en milieu poreux, et (2) la biodégradation de polluants dissous par une phase stationnaire de bactéries. Les recherches conduites au cours des dix dernières années indiquent que ces processus sont intimement liés. Cette liaison peut intervenir lorsqu
Heat Conduction and Characteristic Size of Fractal Porous Media
Institute of Scientific and Technical Information of China (English)
WANG Wei-Wei; HUAI Xiu-Lan; TAO Yu-Jia
2006-01-01
Based on fractal theory, two types of random Sierpinski carpets (RSCs) and their periodic structures are generated to model the structures of natural porous media, and the heat conduction in these structures is simulated by the finite volume method. The calculated results indicate that in a certain range of length scales, the size and spatial arrangement of pores have significant influence on the effective thermal conductivity, and the heat conduction presents the aeolotropic characteristic. Above the length scale, however, the influence of size and spatial arrangement of pores on the effective thermal conductivity reduces gradually with the increasing characteristic size of porous media, the aeolotropic characteristic is weakened gradually. It is concluded that the periodicity in structures of porous media is not equal to the periodicity in heat conduction.
A volume-balance model for flow on porous media
Malaga, Carlos; Mandujano, Francisco; Becerra, Julian
2015-11-01
Volume-balance models are used by petroleum engineers for simulating multiphase and multicomponent flow phenomena in porous media and the extraction process in oil reservoirs. In these models, mass conservation equations and Darcy's law are supplemented by a balance condition for the pore and fluid volumes. This provides a pressure equation suitable for simulating a compressible flow within a compressible solid matrix. Here we present an alternative interpretation of the volume-balance condition that includes the advective transport within a consolidated porous media. We obtain a modified equation for the time evolution of the pressure field. Numerical tests for phase separation under gravity are presented for multiphase three dimensional flow in heterogeneous porous media. The authors acknowledge funding from Fondo Sectorial CONACYT-SENER grant number 42536 (DGAJ-SPI-34-170412-217).
Permeability of mono- and bi-dispersed porous media
Directory of Open Access Journals (Sweden)
Kim S.J.
2013-04-01
Full Text Available In this study, the permeability of mono- and bi-dispersed porous media is considered. The effects of the particle size distribution and the packing structure of particles on the permeability are investigated experimentally and analytically. Both experimental and analytic results suggest that the particlesize distribution is close to the log-normal distribution, and the permeability of the mono-dispersed porous media quasi-linearly decreases as the range of the particle size distribution increases. On the other hand, the effect of packing structure of particles on the permeability is shown to be negligible.The permeability of the bidispersed porous media quasi-linearly decreases as the range of cluster size increases, and nearly independent of the particle size distribution. The present model is valid over the range of parameters typically found in heat transfer applications.
Lattice Boltzmann implementation for Fluids Flow Simulation in Porous Media
Directory of Open Access Journals (Sweden)
Xinming Zhang
2011-06-01
Full Text Available In this paper, the lattice-Boltzmann method is developed to investigate the behavior of isothermal two-phase fluid flow in porous media. The method is based on the Shan–Chen multiphase model of nonideal fluids that allow coexistence of two phases of a single substance. We reproduce some different idealized situations (phase separation, surface tension, contact angle, pipe flow, and fluid droplet motion, et al in which the results are already known from theory or laboratory measurements and show the validity of the implementation for the physical two-phase flow in porous media. Application of the method to fluid intrusion in porous media is discussed and shows the effect of wettability on the fluid flow. The capability of reproducing critical flooding phenomena under strong wettability conditions is also proved.
Channelization in Porous Media driven by Erosion and Deposition
Jäger, Robin; Herrmann, Hans Jürgen
2016-01-01
We develop and validate a new model to study simultaneous erosion and deposition in three-dimensional porous media. We study the changes of the porous structure induced by the deposition and erosion of matter on the solid surface and find that when both processes are active, channelization in the porous structure always occurs. The channels can be stable or only temporary depending mainly on the driving mechanism. Whereas a fluid driven by a constant pressure drop in general does not form steady channels, imposing a constant flux always produces stable channels within the porous structure. Furthermore we investigate how changes of the local deposition and erosion properties affect the final state of the porous structure, finding that the larger the range of wall shear stress for which there is neither erosion nor deposition, the more steady channels are formed in the structure.
Institute of Scientific and Technical Information of China (English)
SHU Wei-Xing; LUO Hai-Lu; LI Fei; REN Zhong-Zhou
2006-01-01
@@ We investigate the propagation of electromagnetic waves at the interface between an isotropic material and the anisotropic medium with a unique dispersion relation. We show that the refraction behaviour of E-polarized waves is opposite to that of H-polarized waves, though the dispersion relations for E- and H-polarized waves are the same. It is found that waves exhibit different propagation properties in anisotropic media with different sign combinations of the permittivity and permeability tensors. Some interesting properties of propagation are also found in the special anisotropic media, leading to potential applications.
Linking Colloid Deposit Morphology and Clogging in Porous Media
Roth, E. J.; Mont-eton, M. E.; Mays, D. C.
2012-12-01
Innovations in the field of groundwater remediation have been hampered by delivery limitations in the porous media. For example, colloid deposits (comprising clays or silts) can cause a detrimental reduction in permeability, or clogging, which is problematic for groundwater remediation as well as granular media filtration and aquifer storage and recovery. During remediation, clogging creates preferential pathways in the media, leading to localized rather than spatially extensive contaminant treatment. Consequentially, remediation efforts become more expensive, less effective, and take a very long time. This presentation describes ongoing research investigating the link between colloid deposit morphology and clogging in porous media. As described by Darcy's Law, the velocity of fluid flow through porous media is proportional to permeability, which depends, in part, on porosity. However, changes in permeability are not in accord with changes in porosity as predicted by the Kozeny-Carman equation. It is hypothesized that unmeasured aspects of colloid deposit morphology could be the cause of this anomaly. Colloidal phenomena have important and dynamic effects on the permeability of natural porous media, and several lines of evidence suggest a correlation between clogging in porous media and the fractal dimension of colloid deposits. Here, a custom-built static light scattering apparatus is used to measure the fractal dimension of colloid deposits in refractive index matched porous media within a flow column. The media in our flow column is Nafion, which becomes essentially invisible when saturated by a solution of isopropanol and water. Polystyrene microspheres are then added to the influent through the column as a surrogate for natural colloids. Light from a laser is passed through the column, scattering from the deposited colloids, but not from the index matched Nafion. The resulting intensity of scattered light is measured as a function of scattering angle, and then
Density-Driven Compactional Flow in Porous Media
Yang, Xin-She
2010-01-01
In the mathematical modelling of compactional flow in porous media, the constitutive relation is typically modelled in terms of a nonlinear relationship between effective pressure and porosity, and compaction is essentially poroelastic. However, at depths deeper than 1 km where pressure is high, compaction becomes more akin to a viscous one. Two mathematical models of compaction in porous media are formulated and the noninear equations are then solved numerically. The essential features of numerical profiles of poroelastic and viscous compaction are thus compared with asymptotic solutions. Two distinguished styles of density-driven compaction in fast and slow compacting sediments are analysed and shown in this paper.
Traveling time and traveling length for flow in porous media
Lee, Youngki; Andrade Jr., Jose S.; Buldyrev, Sergey V.; Dokholyan, Nikolay V.; Havlin, Shlomo; King, Peter R.; Paul, Gerald; Stanley, H. Eugene
1999-01-01
We study traveling time and traveling length for tracer dispersion in porous media. We model porous media by two-dimensional bond percolation, and we model flow by tracer particles driven by a pressure difference between two points separated by Euclidean distance $r$. We find that the minimal traveling time $t_{min}$ scales as $t_{min} \\sim r^{1.40}$, which is different from the scaling of the most probable traveling time, ${\\tilde t} \\sim r^{1.64}$. We also calculate the length of the path c...
Chaotic advection in 2D anisotropic porous media
Varghese, Stephen; Speetjens, Michel; Trieling, Ruben; Toschi, Federico
2015-11-01
Traditional methods for heat recovery from underground geothermal reservoirs employ a static system of injector-producer wells. Recent studies in literature have shown that using a well-devised pumping scheme, through actuation of multiple injector-producer wells, can dramatically enhance production rates due to the increased scalar / heat transport by means of chaotic advection. However the effect of reservoir anisotropy on kinematic mixing and heat transport is unknown and has to be incorporated and studied for practical deployment in the field. As a first step, we numerically investigate the effect of anisotropy (both magnitude and direction) on (chaotic) advection of passive tracers in a time-periodic Darcy flow within a 2D circular domain driven by periodically reoriented diametrically opposite source-sink pairs. Preliminary results indicate that anisotropy has a significant impact on the location, shape and size of coherent structures in the Poincare sections. This implies that the optimal operating parameters (well spacing, time period of well actuation) may vary strongly and must be carefully chosen so as to enhance subsurface transport. This work is part of the research program of the Foundation for Fundamental Research on Matter (FOM), which is part of Netherlands Organisation for Scientific Research (NWO). This research program is co-financed by Shell Global Solutions International B.V.
Pressure diffusion waves in porous media
Energy Technology Data Exchange (ETDEWEB)
Silin, Dmitry; Korneev, Valeri; Goloshubin, Gennady
2003-04-08
Pressure diffusion wave in porous rocks are under consideration. The pressure diffusion mechanism can provide an explanation of the high attenuation of low-frequency signals in fluid-saturated rocks. Both single and dual porosity models are considered. In either case, the attenuation coefficient is a function of the frequency.
Directory of Open Access Journals (Sweden)
Sophia Haussener
2012-01-01
Full Text Available High-resolution X-ray computed tomography is employed to obtain the exact 3D geometrical configuration of porous anisotropic ceria applied in solar-driven thermochemical cycles for splitting H2O and CO2. The tomography data are, in turn, used in direct pore-level numerical simulations for determining the morphological and effective heat/mass transport properties of porous ceria, namely: porosity, specific surface area, pore size distribution, extinction coefficient, thermal conductivity, convective heat transfer coefficient, permeability, Dupuit-Forchheimer coefficient, and tortuosity and residence time distributions. Tailored foam designs for enhanced transport properties are examined by means of adjusting morphologies of artificial ceria samples composed of bimodal distributed overlapping transparent spheres in an opaque medium.
Wang, Hui
2014-05-01
This thesis addresses the efficiency improvement of seismic wave modeling and migration in anisotropic media. This improvement becomes crucial in practice as the process of imaging complex geological structures of the Earth\\'s subsurface requires modeling and migration as building blocks. The challenge comes from two aspects. First, the underlying governing equations for seismic wave propagation in anisotropic media are far more complicated than that in isotropic media which demand higher computational costs to solve. Second, the usage of whole prestack seismic data still remains a burden considering its storage volume and the existing wave equation solvers. In this thesis, I develop two approaches to tackle the challenges. In the first part, I adopt the concept of prestack exploding reflector model to handle the whole prestack data and bridge the data space directly to image space in a single kernel. I formulate the extrapolation operator in a two-way fashion to remove he restriction on directions that waves propagate. I also develop a generic method for phase velocity evaluation within anisotropic media used in this extrapolation kernel. The proposed method provides a tool for generating prestack images without wavefield cross correlations. In the second part of this thesis, I approximate the anisotropic models using effective isotropic models. The wave phenomena in these effective models match that in anisotropic models both kinematically and dynamically. I obtain the effective models through equating eikonal equations and transport equations of anisotropic and isotropic models, thereby in the high frequency asymptotic approximation sense. The wavefields extrapolation costs are thus reduced using isotropic wave equation solvers while the anisotropic effects are maintained through this approach. I benchmark the two proposed methods using synthetic datasets. Tests on anisotropic Marmousi model and anisotropic BP2007 model demonstrate the applicability of my
Mathematical models of a diffusion-convection in porous media
Directory of Open Access Journals (Sweden)
Anvarbek M. Meirmanov
2012-06-01
Full Text Available Mathematical models of a diffusion-convection in porous media are derived from the homogenization theory. We start with the mathematical model on the microscopic level, which consist of the Stokes system for a weakly compressible viscous liquid occupying a pore space, coupled with a diffusion-convection equation for the admixture. We suppose that the viscosity of the liquid depends on a concentration of the admixture and for this nonlinear system we prove the global in time existence of a weak solution. Next we rigorously fulfil the homogenization procedure as the dimensionless size of pores tends to zero, while the porous body is geometrically periodic. As a result, we derive new mathematical models of a diffusion-convection in absolutely rigid porous media.
Towards aeroacoustic sound generation by flow through porous media.
Hasert, Manuel; Bernsdorf, Joerg; Roller, Sabine
2011-06-28
In this work, we present single-step aeroacoustic calculations using the Lattice Boltzmann method (LBM). Our application case consists of the prediction of an acoustic field radiating from the outlet of a porous media silencer. It has been proved that the LBM is able to simulate acoustic wave generation and propagation. Our particular aim is to validate the LBM for aeroacoustics in porous media. As a validation case, we consider a spinning vortex pair emitting sound waves as the vortices rotate around a common centre. Non-reflective boundary conditions based on characteristics have been adopted from Navier-Stokes methods and are validated using the time evolution of a Gaussian pulse. We show preliminary results of the flow through the porous medium.
A non-Darcian approach to flows through porous media
International Nuclear Information System (INIS)
Darcy's law is inadequate to describe viscous flows through porous media near solid boundaries-interfaces, permeable or not, and also at high speeds. The convective accelerations and viscous stresses play a dominating role in determining the flow pattern in a layer close to such surfaces. Of course, the flow at large distances is very much closer to the Darcian flow
Transport of multiple Escherichia coli strains in saturated porous media
Lutterodt, G.
2012-01-01
The deviation of bacteria transport and deposition patterns on grains in porous media from theory has resulted in the inability to accurately predict transport distances in aquifers, with consequences of polluting drinking water sources (springs, boreholes and wells). Due to the importance of Escher
Simulation of impaction filtration of aerosol droplets in porous media
Ghazaryan, Lilya; Lopez Penha, David J.; Geurts, Bernard J.; Stolz, Steffen; Winkelmann, Christoph; Pereira, J.C.F.; Sequeira, A.; Pereira, J.M.C.
2010-01-01
We report on the development of a method to simulate from first principles the particle filtration efficiency of filters that are composed of structured porous media. We assume that the ratio of particle density to the fluid density is high. We concentrate on the motion of the particles in a laminar
Fractal and Multifractal Models Applied to Porous Media - Editorial
Given the current high level of interest in the use of fractal geometry to characterize natural porous media, a special issue of the Vadose Zone Journal was organized in order to expose established fractal analysis techniques and cutting-edge new developments to a wider Earth science audience. The ...
Microscopic interfacial phenomena during flow in porous media
Energy Technology Data Exchange (ETDEWEB)
Miksis, M.J.; Ida, M.P. [Northwestern Univ., Evanston, IL (United States)
1996-12-31
A fundamental process during any multiphase flow in porous media is the breaking apart of one of the phases into smaller components. Here the authors investigate this breaking process as applied to a thin liquid film. They study the breaking of both a two dimensional planar film and a cylindrical thread of liquid using both analytical and numerical methods.
Acoustic Wave Monitoring of Biofilm Development in Porous Media
Biofilm development in porous media can result in significant changes to the hydrogeological properties of subsurface systems with implications for fluid flow and contaminant transport. As such, a number of numerical models and simulations have been developed in an attempt to qua...
Fluid effect on wave propagation in heterogeneous porous media
Vogelaar, B.B.S.A.
2009-01-01
Acoustic wave propagation through porous media is affected by the properties of the pore fluid and the matrix material. The acoustic velocity is extensively used for imaging of subsurface strata, and to predict petrophysical properties. In contrast, the attenuation (loss of wave energy) is not routi
Determination of permeability using fractal method for porous media
Institute of Scientific and Technical Information of China (English)
施明恒; 陈永平
2001-01-01
A theoretical formulation was developed to express permeability as a function of different fractal dimensions and other scales for porous media . The effective fractal void ratio, the spectral dimension and the fractal dimension of particle mass distribution were introduced. The permeabilities for different soils in China are calculated. The predicted permeability for rice soil was compared with the measured data available in literature.
Upscaling of flow in porous media from a tracer perspective
Berentsen, C.W.J.
2003-01-01
Most of our knowledge of flow in porous media is obtained at the pore and the macro scale. For reservoir scale modelling it is not practical to model the flow at these fine scales. Considering the usual objectives (e.g. large scale flow pattern and production forecast) it is undesirable to have to g
Coupled electric and transport phenomena in porous media
Li, Shuai
2014-01-01
The coupled electrical and transport properties of clay-containing porous media are the topics of interest in this study. Both experimental and numerical (pore network modeling) techniques are employed to gain insight into the macro-scale interaction between electrical and solute transport phenomena
magnetic resonance of 3He nuclei in porous media
International Nuclear Information System (INIS)
The data on 3He spin kinetics in porous media above the Fermi temperature of 3He are summarized. Presented results are obtained in Kazan Federal University in last ten years and are the base of developing method of helium porometry. Guidelines for investigation of samples with unknown pore sizes and superficial their properties are proposed
Dispersion of charged tracers in charged porous media
B. Rotenberg; I. Pagonabarraga; D. Frenkel
2008-01-01
We report a lattice-Boltzmann scheme to compute the dispersion of charged tracers in charged porous media under the combined effect of advection, diffusion and electro-migration. To this end, we extend the moment propagation approach, introduced to study the dispersion of neutral tracers (Lowe C. an
Diffusive–Dispersive and Reactive Fronts in Porous Media
DEFF Research Database (Denmark)
Haberer, Christina M.; Muniruzzaman, Muhammad; Grathwohl, Peter;
2015-01-01
Diffusive–dispersive mass transfer is important for many groundwater quality problems as it drives the interaction between different reactants, thus influencing a wide variety of biogeochemical processes. In this study, we performed laboratory experiments to quantify O2 transport in porous media...
MECHANISM FOR VISCOELASTIC POLYMER SOLUTION PERCOLATING THROUGH POROUS MEDIA
Institute of Scientific and Technical Information of China (English)
ZHANG Li-juan; YUE Xiang-an
2007-01-01
The pore throat of porous media is modeled as a constricted channel or expanded channel. The flow of viscoelastic polymer solution in pore throat model is studied by numerical method. Relationship between pressure drop and flow rate is developed, viscoelasticity and throat size are found to be two main factors in high flow resistance. According to pore throat model, 2-D stochastic channel bundle is put forward to model porous media, which is composed of pore throat models in series - parallel connection with size and length accord to Haring - Greenkorn stochastic distribution. Percolation model of viscoelastic fluid is developed on the basis of Darcy equation and pressure drop vs. flow rate relation in 2-D stochastic channel bundle. Results indicate that the seepage ability of viscoelastic polymer solution decreases with the increase of viscoelasticity, injection rate, and heterogeneity as well as the decrease of mean pore size of porous media. The high pressure drop of viscoelastic fluid at the connection of pore to throat plays a great role in its anomalous high flow resistance through porous media.
Brine transport in porous media self-similar solutions
Duijn, C.J. van; Peletier, L.A.; Schotting, R.J.
1996-01-01
In this paper we analyze a model for brine transport in porous media, which includes a mass balance for the fluid, a mass balance for salt, Darcy's law and an equation of state, which relates the fluid density to the salt mass fraction. This model incorporates the effect of local volume changes due
Coupled Flow and Reactivity in the Variably Saturated Porous Media
Energy Technology Data Exchange (ETDEWEB)
Palmer, Carl; Smith Bob W.
2003-06-01
This Environmental Management Science Program project (86598) is a collaborative effort between the University of Idaho (UI) and the Idaho National Engineering and Environmental Laboratory (INEEL) with the goal of developing a better understanding of the relationships between chemical reactivity, moisture content, and reactive transport for vadose zone porous media.
Institute of Scientific and Technical Information of China (English)
Zhiming Chen
2006-01-01
We review some of our recent efforts in developing upscaling methods for simulating the flow transport through heterogeneous porous media. In particular, the steady flow transport through highly heterogeneous porous media driven by extraction wells and the flow transport through unsaturated porous media will be considered.
Superfluid Helium Flow in Porous Media
Allain, Hervé; Quintard, Michel; Soulaine, Cyprien; Prat, Marc; Baudouy, Bertrand; Van Weelderen, Rob
2013-01-01
Superfluid helium is primarily used in the field of applied superconductivity. Given the complexity of the magnet geometry and the scales involved, a real 3D simulation of heat transfer in such devices at the micro-channel scale is very difficult, even impossible. However, the repeatability or even periodicity of the structure suggests the possibility of a macro-scale description following a porous medium approach. Which macro-scale model may be used? This largely remains an open field while ...
An iterative, fast-sweeping-based eikonal solver for 3D tilted anisotropic media
Waheed, Umair bin
2015-03-30
Computation of first-arrival traveltimes for quasi-P waves in the presence of anisotropy is important for high-end near-surface modeling, microseismic-source localization, and fractured-reservoir characterization - and it requires solving an anisotropic eikonal equation. Anisotropy deviating from elliptical anisotropy introduces higher order nonlinearity into the eikonal equation, which makes solving the eikonal equation a challenge. We addressed this challenge by iteratively solving a sequence of simpler tilted elliptically anisotropic eikonal equations. At each iteration, the source function was updated to capture the effects of the higher order nonlinear terms. We used Aitken\\'s extrapolation to speed up convergence rate of the iterative algorithm. The result is an algorithm for computing first-arrival traveltimes in tilted anisotropic media. We evaluated the applicability and usefulness of our method on tilted transversely isotropic media and tilted orthorhombic media. Our numerical tests determined that the proposed method matches the first arrivals obtained by wavefield extrapolation, even for strongly anisotropic and highly complex subsurface structures. Thus, for the cases where two-point ray tracing fails, our method can be a potential substitute for computing traveltimes. The approach presented here can be easily extended to compute first-arrival traveltimes for anisotropic media with lower symmetries, such as monoclinic or even the triclinic media.
3-D waveform tomography sensitivity kernels for anisotropic media
Djebbi, R.
2014-01-01
The complications in anisotropic multi-parameter inversion lie in the trade-off between the different anisotropy parameters. We compute the tomographic waveform sensitivity kernels for a VTI acoustic medium perturbation as a tool to investigate this ambiguity between the different parameters. We use dynamic ray tracing to efficiently handle the expensive computational cost for 3-D anisotropic models. Ray tracing provides also the ray direction information necessary for conditioning the sensitivity kernels to handle anisotropy. The NMO velocity and η parameter kernels showed a maximum sensitivity for diving waves which results in a relevant choice of those parameters in wave equation tomography. The δ parameter kernel showed zero sensitivity; therefore it can serve as a secondary parameter to fit the amplitude in the acoustic anisotropic inversion. Considering the limited penetration depth of diving waves, migration velocity analysis based kernels are introduced to fix the depth ambiguity with reflections and compute sensitivity maps in the deeper parts of the model.
Heat and mass transfer in unsaturated porous media. Final report
Energy Technology Data Exchange (ETDEWEB)
Childs, S.W.; Malstaff, G.
1982-02-01
A preliminary study of heat and water transport in unsaturated porous media is reported. The project provides background information regarding the feasibility of seasonal thermal energy storage in unconfined aquifers. A parametric analysis of the factors of importance, and an annotated bibliography of research findings pertinent to unconfined aquifer thermal energy storage (ATES) are presented. This analysis shows that heat and mass transfer of water vapor assume dominant importance in unsaturated porous media at elevated temperature. Although water vapor fluxes are seldom as large as saturated medium liquid water fluxes, they are important under unsaturated conditions. The major heat transport mechanism for unsaturated porous media at temperatures from 50 to 90/sup 0/C is latent heat flux. The mechanism is nonexistent under saturated conditions but may well control design of unconfined aquifer storage systems. The parametric analysis treats detailed physical phenomena which occur in the flow systems study and demonstrates the temperature and moisture dependence of the transport coefficients of importance. The question of design of an unconfined ATES site is also addressed by considering the effects of aquifer temperature, depth to water table, porous medium flow properties, and surface boundary conditions. Recommendations are made for continuation of this project in its second phase. Both scientific and engineering goals are considered and alternatives are presented.
Particle dispersion and deposition in porous media: a computational perspective
Boccardo, Gianluca; Crevacore, Eleonora; Sethi, Rajandrea; Marchisio, Daniele
2015-11-01
This work investigates particle dispersion in porous media, which is of central relevance in a number of applications ranging from groundwater remediation tochemical engineering. The challenge lies in studying the complex fluid dynamics behavior arising at the microscale (very difficult to observe experimentally) and obtaining transport models to be employed at the macroscopic scale of interest. While a wealth of studies have approached this problem, the case of particle transport with a concurrent heterogeneous chemical reaction (e.g.: particle deposition) still lacks a satisfactory description, especially when considering a polydisperse population of solid particles. Moreover, the oft-used simplified descriptions of the porous medium (via array of spheres or similar strategies) fail to fully take into account the effect of the packing structure. Our novel approach relies on an ``in-silico'' procedure where many 3-D realistic porous media models are constructed via rigid-body simulations and fluid flowand particle transport are then investigated through computational fluid dynamics. The results evidence the need for a deeper look, afforded by these methodology, into the influence of the features of realistic porous media on particle transport and deposition.
Studies of Tracer Dispersion and Fluid Flow in Porous Media
Energy Technology Data Exchange (ETDEWEB)
Rage, T.
1996-12-31
This doctoral thesis explores the connection between the topology of a porous medium and its macroscopic transport properties and is based on computerized simulation. In porous media, both diffusion and convection contribute to the dispersion of a tracer and their combined effect is emphasized. The governing equations are solved numerically, using finite differences and Monte Carlo technique. The influence of finite Reynolds number on the outcome of echo-experiments is discussed. Comparing experiments and simulations it is found that nonlinear inertial forces lead to a visible deformation of a returned tracer at surprisingly small Reynolds numbers. In a study of tracer dispersion and fluid flow in periodic arrays of discs it is demonstrated that the mechanisms of mechanical dispersion in periodic media and in natural (non-periodic) porous media are essentially different. Measurements of the percolation probability distribution of a sandstone sample is presented. Local porosity theory predicts that this simple geometric function of a porous medium is of dominant importance for its macroscopic transport properties. It is demonstrated that many aspects of transport through fractures can be studied by using simple but realistic models and readily available computer resources. An example may be the transport of hydrocarbon fluids from the source rock to a reservoir. 165 refs., 44 figs., 1 table
Statistical mechanics of unsaturated porous media
Xu, Jin; Louge, Michel Y.
2015-12-01
We explore a mean-field theory of fluid imbibition and drainage through permeable porous solids. In the limit of vanishing inertial and viscous forces, the theory predicts the hysteretic "retention curves" relating the capillary pressure applied across a connected domain to its degree of saturation in wetting fluid in terms of known surface energies and void space geometry. To avoid complicated calculations, we adopt the simplest statistical mechanics, in which a pore interacts with its neighbors through narrow openings called "necks," while being either full or empty of wetting fluid. We show how the main retention curves can be calculated from the statistical distribution of two dimensionless parameters λ and α measuring the specific areas of, respectively, neck cross section and wettable pore surface relative to pore volume. The theory attributes hysteresis of these curves to collective first-order phase transitions. We illustrate predictions with a porous domain consisting of a random packing of spheres, show that hysteresis strength grows with λ and weakens as the distribution of α broadens, and reproduce the behavior of Haines jumps observed in recent experiments on an ordered pore network.
Statistical mechanics of unsaturated porous media.
Xu, Jin; Louge, Michel Y
2015-12-01
We explore a mean-field theory of fluid imbibition and drainage through permeable porous solids. In the limit of vanishing inertial and viscous forces, the theory predicts the hysteretic "retention curves" relating the capillary pressure applied across a connected domain to its degree of saturation in wetting fluid in terms of known surface energies and void space geometry. To avoid complicated calculations, we adopt the simplest statistical mechanics, in which a pore interacts with its neighbors through narrow openings called "necks," while being either full or empty of wetting fluid. We show how the main retention curves can be calculated from the statistical distribution of two dimensionless parameters λ and α measuring the specific areas of, respectively, neck cross section and wettable pore surface relative to pore volume. The theory attributes hysteresis of these curves to collective first-order phase transitions. We illustrate predictions with a porous domain consisting of a random packing of spheres, show that hysteresis strength grows with λ and weakens as the distribution of α broadens, and reproduce the behavior of Haines jumps observed in recent experiments on an ordered pore network. PMID:26764701
Polarisations of quasi-waves in a general anisotropic porous solid saturated with viscous liquid
Indian Academy of Sciences (India)
M D Sharma
2005-08-01
Wave propagation is studied in a general anisotropic poroelastic solid saturated with a viscous fluid flowing through its pores of anisotropic permeability. The extended version of Biot's theory is used to derive a system of modified Christoffel equations for the propagation of plane harmonic waves in such media. The non-trivial solution of this system is ensured by a biquadratic equation whose roots represent the complex velocities of four attenuating quasi-waves in the medium. These complex velocities define phase velocity and attenuation of each quasi-wave propagating along a given phase direction in three-dimensional space. The solution itself defines the polarisations of the quasi-waves along with phase shift. The variations of polarisations of quasi-waves with their phase direction, are computed for a realistic numerical model.
Energy Technology Data Exchange (ETDEWEB)
Borgne, H.
2004-12-01
modelling of waves propagation in anisotropic media. With the approximations of ray theory, 1 develop an expression of the geometrical spreading, the amplitude, and their reciprocity relations. I set up imaging formulas in order to reconstruct the reflection coefficients of the subsurface in elastic anisotropic media. In a first time, 1 salve the direct problem, by expressing the integral relation between the scattered wave field recorded by the receivers and the subsurface reflection coefficients. In a second time, 1 apply an elastic anisotropic quantitative migration method, based on the properties of the inverse Radon transforms (Beylkin's approach), in order to express the reflection coefficient in 2D, 2.5D and 3D media. 1 implemented these formulas in a new preserved amplitude migration algorithm, where the images are sorted by angle classes. At last, 1 apply these theoretical results to synthetic and real datasets. 1 show that migration is able to reconstruct the correct A V A behavior of anisotropic reflection coefficients if hath. modifications are achieved. Then, 1 degrade the process, by keeping an anisotropic ray tracing but using the classical isotropic imaging formula. F'or this commonly used configuration, 1 evaluate the error that can be expected in the A V A response of the migrated reflection coefficient. Methodological applications show the sensibility of the migration results to the velocity model smoothing and to an error on the anisotropic axis. (author)
MULTIPHASE FLOW AND TRANSPORT IN POROUS MEDIA
Multiphase flow and transport of compositionally complex fluids in geologic media is of importance in a number of applied problems which have major social and economic effects. n petroleum reservoir engineering efficient recovery of energy reserves is the principal goal. nfortuna...
Overlimiting Current and Shock Electrodialysis in Porous Media
Deng, Daosheng; Dydek, E. Victoria; Han, Ji-Hyung; Schlumpberger, Sven; Mani, Ali; Zaltzman, Boris; Bazant, Martin Z.
2013-01-01
Most electrochemical processes, such as electrodialysis, are limited by diffusion, but in porous media, surface conduction and electro-osmotic flow also contribute to ionic fluxes. In this paper, we report experimental evidence for surface-driven over-limiting current (faster than diffusion) and deionization shocks (propagating salt removal) in a porous medium. The apparatus consists of a silica glass frit (1 mm thick with 500 nm mean pore size) in an aqueous electrolyte (CuSO$_4$ or AgNO$_3$...
Power exponential velocity distributions in disordered porous media
Matyka, Maciej; Koza, Zbigniew
2016-01-01
Velocity distribution functions link the micro- and macro-level theories of fluid flow through porous media. Here we study them for the fluid absolute velocity and its longitudinal and lateral components relative to the macroscopic flow direction in a model of a random porous medium. We claim that all distributions follow the power exponential law controlled by an exponent $\\gamma$ and a shift parameter $u_0$ and examine how these parameters depend on the porosity. We find that $\\gamma$ has a universal value $1/2$ at the percolation threshold and grows with the porosity, but never exceeds 2.
Multiphase lattice Boltzmann simulations for porous media applications -- a review
Liu, Haihu; Leonardi, Christopher R; Jones, Bruce D; Schmieschek, Sebastian; Narváez, Ariel; Williams, John R; Valocchi, Albert J; Harting, Jens
2014-01-01
Over the last two decades, lattice Boltzmann methods have become an increasingly popular tool to compute the flow in complex geometries such as porous media. In addition to single phase simulations allowing, for example, a precise quantification of the permeability of a porous sample, a number of extensions to the lattice Boltzmann method are available which allow to study multiphase and multicomponent flows on a pore scale level. In this article we give an extensive overview on a number of these diffuse interface models and discuss their advantages and disadvantages. Furthermore, we shortly report on multiphase flows containing solid particles, as well as implementation details and optimization issues.
Poroelastic Response of Orthotropic Fractured Porous Media
Energy Technology Data Exchange (ETDEWEB)
Berryman, James G.
2011-12-16
An algorithm is presented for inverting either laboratory or field poroelastic data for all the drained constants of an anisotropic (specifically orthotropic) fractured poroelastic system. While fractures normally weaken the system by increasing the mechanical compliance, any liquids present in these fractures are expected to increase the stiffness somewhat, thus negating to some extent the mechanical weakening influence of the fractures themselves. The analysis presented quantifies these effects and shows that the key physical variable needed to account for the pore-fluid effects is a factor of (1 - B), where B is Skempton's second coe fficient and satisfies 0 {<=} B < 1. This scalar factor uniformly reduces the increase in compliance due to the presence of communicating fractures, thereby stiffening the fractured composite medium by a predictable amount. One further goal of the discussion is to determine how many of the poroelastic constants need to be known by other means in order to determine the rest from remote measurements, such as seismic wave propagation data in the field. Quantitative examples arising in the analysis show that, if the fracture aspect ratio a{sub f} ~ 0.1 and the pore fluid is liquid water, then for several cases considered Skempton's B ~ 0:9, so the stiffening effect of the pore-liquid reduces the change in compliance due to the fractures by a factor 1-B ~ 0.1, in these examples. The results do however depend on the actual moduli of the unfractured elastic material, as well as on the pore-liquid bulk modulus, so these quantitative predictions are just examples, and should not be treated as universal results. Attention is also given to two previously unremarked poroelastic identities, both being useful variants of Gassmann's equations for homogeneous -- but anisotropic -- poroelasticity. Relationships to Skempton's analysis of saturated soils are also noted. The paper concludes with a discussion of alternative methods
Prestack exploding reflector modelling and migration for anisotropic media
Alkhalifah, Tariq Ali
2014-10-09
The double-square-root equation is commonly used to image data by downward continuation using one-way depth extrapolation methods. A two-way time extrapolation of the double-square-root-derived phase operator allows for up and downgoing wavefields but suffers from an essential singularity for horizontally travelling waves. This singularity is also associated with an anisotropic version of the double-square-root extrapolator. Perturbation theory allows us to separate the isotropic contribution, as well as the singularity, from the anisotropic contribution to the operator. As a result, the anisotropic residual operator is free from such singularities and can be applied as a stand alone operator to correct for anisotropy. We can apply the residual anisotropy operator even if the original prestack wavefield was obtained using, for example, reverse-time migration. The residual correction is also useful for anisotropic parameter estimation. Applications to synthetic data demonstrate the accuracy of the new prestack modelling and migration approach. It also proves useful in approximately imaging the Vertical Transverse Isotropic Marmousi model.
Ray-optics analysis of inhomogeneous optically anisotropic media
Sluijter, M.
2010-01-01
When the optical behavior of light in a medium depends on the direction in which light is traveling, the medium is called optically anisotropic. Light is an electromagnetic wave and in this thesis, we discuss the electromagnetic theory on optical anisotropy. We do this with the assumption that the w
Upscaling flow and transport properties in synthetic porous media
Jasinski, Lukasz; Dabrowski, Marcin
2015-04-01
Flow and transport through the porous media has instances in nature and industry: contaminant migration in geological formations, gas/oil extraction from proppant filled hydraulic fractures and surrounding porous matrix, underground carbon dioxide sequestration and many others. We would like to understand the behavior of propagating solute front in such medium, mainly flow preferential pathways and the solute dispersion due to the porous medium geometry. The motivation of our investigation is to find connection between the effective flow and transport properties and porous media geometry in 2D and 3D for large system sizes. The challenge is to discover a good way of upscaling flow and transport processes to obtain results comparable to these calculated on pore-scale in much faster way. We study synthetic porous media made of densely packed poly-disperse disk-or spherical-shaped grains in 2D and 3D, respectively. We use various protocols such as the random sequential addition (RSA) algorithm to generate densely packed grains. Imposed macroscopic pressure gradient invokes fluid flow through the pore space of generated porous medium samples. As the flow is considered in the low Reynolds number regime, a stationary velocity field is obtained by solving the Stokes equations by means of finite element method. Void space between the grains is accurately discretized by using body-fitting triangular or tetrahedral mesh. Finally, pure advection of a front carried by the velocity field is studied. Periodicity in all directions is applied to microstructure, flow and transport processes. Effective permeability of the media can be calculated by integrating the velocity field on cross sections, whereas effective dispersion coefficient is deduced by application of centered moment methods on the concentration field of transported solute in time. The effective parameters are investigated as a function of geometrical parameters of the media, such as porosity, specific surface area
Attenuation of Shocks through Porous Media
Lind, Charles A.; Cybyk, Bohdan Z.; Boris, Jay P.
1998-11-01
Structures designed to mitigate the effects of blast and shock waves are important for both accidental and controlled explosions. The net effect of these mitigating structures is to reduce the strength of the transmitted shock thereby reducing the dynamic pressure loading on nearby objects. In the present study, the attenuation of planar blast and shock waves by passage through structured media is numerically studied with the FAST3D model. The FAST3D model is a state-of-the-art, portable, three-dimensional computational fluid dynamics model based on Flux-Corrected Transport and uses the Virtual Cell Embedding algorithm for simulating complex geometries. The effects of media placement, spacing, orientation, and area blockage are parametrically studied to enhance the understanding of the complex processes involved and to determine ways to minimize the adverse effects of these blast waves.
Clearman, W. M.; Cha, J. S.; Ghiaasiaan, S. M.; Kirkconnell, C. S.
2008-03-01
The hydrodynamic parameters associated with steady longitudinal and lateral (radial) flow of helium in several widely-used pulse tube and Stirling cryocooler regenerator fillers were measured and correlated in this investigation. Pressure drops in test sections packed with regenerator fillers were experimentally measured. Computational fluid dynamics (CFD) models of the regenerator test sections and their vicinities were developed and simulations were performed in which the regenerator test sections were modeled as porous media. By iterative repetition of the simulations, the longitudinal and radial permeability and Forchheimer inertial coefficients were determined such that they would lead to agreement between experimental measurements and the simulations. The regenerator fillers included 325 and 400 mesh stainless steel screens, stainless steel metal foam, sintered 400 mesh stainless steel screens, and a stack of micromachined perforated plates. The hydrodynamic response of the regenerator fillers were also correlated as friction factors. The results confirm that the aforementioned regenerator fillers are anisotropic.
Observation of anisotropic diffusion of light in compacted granular porous materials
Alerstam, Erik
2011-01-01
Employing spatially resolved photon time-of-flight spectroscopy, we reveal anisotropic diffusion of light in compressed granular media. Findings correlate well with recent reports of pore structural anisotropy and its pressure dependence, and significantly reshape our understanding of the optics of compacted granular matter. New routes to material characterization and investigations of compression-induced anisotropy are opened, and an urgent need for better understanding of the relation between compression, microstructure and light scattering is disclosed. Important implications for quantitative spectroscopy of powder compacts in general, and pharmaceutical tablets in particular, are also discussed.
Energy Technology Data Exchange (ETDEWEB)
Antonova, A.M.; Moiseikina, I.I. [Kiev Univ. (Ukraine)
1994-10-05
We consider nonstationary seepage in a bounded nonhomogeneously anisotropic fissured-porous layer. The layer contains by an imperfect well, which operates with a constant discharge. Formulas for the distribution of fluid pressure are obtained using the Laplace transform and the separation of variables method.
Horizontal flow and capillarity-driven redistribution in porous media.
Doster, F; Hönig, O; Hilfer, R
2012-07-01
A recent macroscopic mixture theory for two-phase immiscible displacement in porous media has introduced percolating and nonpercolating phases. Quasi-analytic solutions are computed and compared to the traditional theory. The solutions illustrate physical insights and effects due to spatiotemporal changes of nonpercolating phases, and they highlight the differences from traditional theory. Two initial and boundary value problems are solved in one spatial dimension. In the first problem a fluid is displaced by another fluid in a horizontal homogeneous porous medium. The displacing fluid is injected with a flow rate that keeps the saturation constant at the injection point. In the second problem a horizontal homogeneous porous medium is considered which is divided into two subdomains with different but constant initial saturations. Capillary forces lead to a redistribution of the fluids. Errors in the literature are reported and corrected.
Soltanian, Mohamad Reza; Ritzi, Robert W; Dai, Zhenxue; Huang, Chao Cheng
2015-03-01
Physical and chemical heterogeneities have a large impact on reactive transport in porous media. Examples of heterogeneous attributes affecting reactive mass transport are the hydraulic conductivity (K), and the equilibrium sorption distribution coefficient (Kd). This paper uses the Deng et al. (2013) conceptual model for multimodal reactive mineral facies and a Lagrangian-based stochastic theory in order to analyze the reactive solute dispersion in three-dimensional anisotropic heterogeneous porous media with hierarchical organization of reactive minerals. An example based on real field data is used to illustrate the time evolution trends of reactive solute dispersion. The results show that the correlation between the hydraulic conductivity and the equilibrium sorption distribution coefficient does have a significant effect on reactive solute dispersion. The anisotropy ratio does not have a significant effect on reactive solute dispersion. Furthermore, through a sensitivity analysis we investigate the impact of changing the mean, variance, and integral scale of K and Kd on reactive solute dispersion. PMID:25532767
Soltanian, Mohamad Reza; Dai, Zhenxue; Huang, Chaocheng
2014-01-01
Physical and chemical heterogeneities have a large impact on reactive transport in porous media. Examples of heterogeneous attributes affecting reactive mass transport are the hydraulic conductivity (K), and the equilibrium sorption distribution coefficient (Kd). This paper uses the Deng et al. (2013) conceptual model for multimodal reactive mineral facies and a Lagrangian-based stochastic theory in order to analyze the reactive solute dispersion in three-dimensional anisotropic heterogeneous porous media with hierarchical organization of reactive minerals. An example based on real field data is used to illustrate the time evolution trends of reactive solute dispersion. The results show that the correlation between the hydraulic conductivity and the equilibrium sorption distribution coefficient does have a significant effect on reactive solute dispersion. The anisotropy ratio does not have a significant effect on reactive solute dispersion. Furthermore, through a sensitivity analysis we investigate the impact...
Anisotropic fractal media by vector calculus in non-integer dimensional space
International Nuclear Information System (INIS)
A review of different approaches to describe anisotropic fractal media is proposed. In this paper, differentiation and integration non-integer dimensional and multi-fractional spaces are considered as tools to describe anisotropic fractal materials and media. We suggest a generalization of vector calculus for non-integer dimensional space by using a product measure method. The product of fractional and non-integer dimensional spaces allows us to take into account the anisotropy of the fractal media in the framework of continuum models. The integration over non-integer-dimensional spaces is considered. In this paper differential operators of first and second orders for fractional space and non-integer dimensional space are suggested. The differential operators are defined as inverse operations to integration in spaces with non-integer dimensions. Non-integer dimensional space that is product of spaces with different dimensions allows us to give continuum models for anisotropic type of the media. The Poisson's equation for fractal medium, the Euler-Bernoulli fractal beam, and the Timoshenko beam equations for fractal material are considered as examples of application of suggested generalization of vector calculus for anisotropic fractal materials and media
Anisotropic fractal media by vector calculus in non-integer dimensional space
Tarasov, Vasily E.
2014-08-01
A review of different approaches to describe anisotropic fractal media is proposed. In this paper, differentiation and integration non-integer dimensional and multi-fractional spaces are considered as tools to describe anisotropic fractal materials and media. We suggest a generalization of vector calculus for non-integer dimensional space by using a product measure method. The product of fractional and non-integer dimensional spaces allows us to take into account the anisotropy of the fractal media in the framework of continuum models. The integration over non-integer-dimensional spaces is considered. In this paper differential operators of first and second orders for fractional space and non-integer dimensional space are suggested. The differential operators are defined as inverse operations to integration in spaces with non-integer dimensions. Non-integer dimensional space that is product of spaces with different dimensions allows us to give continuum models for anisotropic type of the media. The Poisson's equation for fractal medium, the Euler-Bernoulli fractal beam, and the Timoshenko beam equations for fractal material are considered as examples of application of suggested generalization of vector calculus for anisotropic fractal materials and media.
Anisotropic fractal media by vector calculus in non-integer dimensional space
Energy Technology Data Exchange (ETDEWEB)
Tarasov, Vasily E., E-mail: tarasov@theory.sinp.msu.ru [Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, Moscow 119991 (Russian Federation)
2014-08-15
A review of different approaches to describe anisotropic fractal media is proposed. In this paper, differentiation and integration non-integer dimensional and multi-fractional spaces are considered as tools to describe anisotropic fractal materials and media. We suggest a generalization of vector calculus for non-integer dimensional space by using a product measure method. The product of fractional and non-integer dimensional spaces allows us to take into account the anisotropy of the fractal media in the framework of continuum models. The integration over non-integer-dimensional spaces is considered. In this paper differential operators of first and second orders for fractional space and non-integer dimensional space are suggested. The differential operators are defined as inverse operations to integration in spaces with non-integer dimensions. Non-integer dimensional space that is product of spaces with different dimensions allows us to give continuum models for anisotropic type of the media. The Poisson's equation for fractal medium, the Euler-Bernoulli fractal beam, and the Timoshenko beam equations for fractal material are considered as examples of application of suggested generalization of vector calculus for anisotropic fractal materials and media.
Analytic studies of colloid transport in fractured porous media
International Nuclear Information System (INIS)
We analyze the interactive migration of radioactive colloids and solute in fractured rock. Two possible interactions between radionuclides as colloids and as solute are considered: solute sorption on nonradioactive colloids to form pseudocolloids, and dissolution of radioactive colloids. Previous studies have discussed the formation and transport of colloids in porous media, including removal of colloids by filtration and sedimentation. Colloids can migrate faster than solute because of weaker sorption on stationary solids and because of hydrochromatography of colloid particles in flow channels. However, the migration of colloids and pseudocolloids can be retarded by the interaction of colloids with solute, and the migration of solute in local equilibrium with colloids can be more rapid than if colloids were not present. Here we present a new quantative analysis to predict the interactive migration of colloids and solute in porous and fractured media. 4 figs
Analysis of Cryptosporidium parvum oocyst transport in porous media
Kim, Song-Bae; Yavuz Corapcioglu, M.
2004-08-01
Cryptosporidium parvum is a protozoan parasite, transmitted through aqueous environments in the form of an oocyst. In this study, a transport model into which sorption, filtration and inactivation mechanisms are incorporated is applied to simulate laboratory column data, and the suitability of a kinetic model to describe the C. parvum oocyst transport and removal in porous media is compared with an equilibrium model. The kinetic model is applied to simulate previous column experimental data and successfully simulates the concentration peak; the late time tailing effect appeared in the breakthrough curves, indicating that the kinetic model is more suitable than the equilibrium one at simulating the fate and transport of the oocysts in porous media. Simulation illustrates that sorption causes retardation along with a tailing in the breakthrough curve. Additionally, filtration acts as a major mechanism of removing the oocysts from the aqueous phase, whereas the role of inactivation in reducing the viable oocyst concentration is minimal.
Combinatorial model of solute transport in porous media
Institute of Scientific and Technical Information of China (English)
张妙仙; 张丽萍
2004-01-01
Modeling of solute transport is a key issue in the area of soil physics and hydrogeology. The most common approach (the convection-dispersion equation) considers an average convection flow rate and Fickian-like dispersion. Here,we propose a solute transport model in porous media of continuously expanding scale, according to the combinatorics principle. The model supposed actual porous media as a combinative body of many basic segments. First, we studied the solute transport process in each basic segment body, and then deduced the distribution of pore velocity in each basic segment body by difference approximation, finally assembled the solute transport process of each basic segment body into one of the combinative body. The simulation result coincided with the solute transport process observed in test. The model provides useful insight into the solute transport process of the non-Fickian dispersion in continuously expanding scale.
Dissipative particle dynamics model for colloid transport in porous media
Energy Technology Data Exchange (ETDEWEB)
Pan, W.; Tartakovsky, A. M.
2013-08-01
We present that the transport of colloidal particles in porous media can be effectively modeled with a new formulation of dissipative particle dynamics, which augments standard DPD with non-central dissipative shear forces between particles while preserving angular momentum. Our previous studies have demonstrated that the new formulation is able to capture accurately the drag forces as well as the drag torques on colloidal particles that result from the hydrodynamic retardation effect. In the present work, we use the new formulation to study the contact efficiency in colloid filtration in saturated porous media. Note that the present model include all transport mechanisms simultaneously, including gravitational sedimentation, interception and Brownian diffusion. Our results of contact efficiency show a good agreement with the predictions of the correlation equation proposed by Tufenkji and EliMelech, which also incorporate all transport mechanisms simultaneously without the additivity assumption.
Resistance absorption of some groundwater tracers in porous media
Jafari, Fateme
2010-05-01
Absorption of tracer to the aquifer material is among the most important factors which should be considered when a tracing program is considered. In this study, the absorption of the tracer into the porous media is analyzed experimentally for some of the most important and applied tracers as uranine, rhodamine B, eosin, potassium permanganate, sodium chloride and potassium chloride. For each tracer, effect of initial tracer concentration and percentage of fine grain sediments on tracer absorption in porous media is analyzed. According to the final results, rhodamine B and potassium permanganate have the less resistance against absorption to aquifer material, whilst eosin and uranine are the most resistant tracers among the examined ones. Key Words: Tracer, Absorption, Aquifer, Column Method
Boiling heat transfer in porous media composed of particles
International Nuclear Information System (INIS)
The boiling heat transfer in the porous media composed of spherical fuel elements exerts significant influences on the reactor's efficiency and safety. In the present study an experimental setup was designed and the boiling heat transfer in the porous media composed of spheres of regular distribution was investigated. Four spheres with diameters of 5mm, 6mm, 7mm and 8mm were used in the test sections. The greater particle diameter led to lower heat transfer coefficient, and resulted in higher wall superheat of original nucleation boiling. The variation of heat transfer coefficient was divided into three groups according to two-phase flow patterns and void fraction. A correlation of heat transfer coefficient was proposed with a mean relative deviation of ± 16%. (author)
Computation of streaming potential in porous media: Modified permeability tensor
Bandopadhyay, Aditya; DasGupta, Debabrata; Mitra, Sushanta K.; Chakraborty, Suman
2015-11-01
We quantify the pressure-driven electrokinetic transport of electrolytes in porous media through a matched asymptotic expansion based method to obtain a homogenized description of the upscaled transport. The pressure driven flow of aqueous electrolytes over charged surfaces leads to the generation of an induced electric potential, commonly termed as the streaming potential. We derive an expression for the modified permeability tensor, K↔eff, which is analogous to the Darcy permeability tensor with due accounting for the induced streaming potential. The porous media herein are modeled as spatially periodic. The modified permeability tensor is obtained for both topographically simple and complex domains by enforcing a zero net global current. Towards resolving the complicated details of the porous medium in a computationally efficient framework, the domain identification and reconstruction of the geometries are performed using adaptive quadtree (in 2D) and octree (in 3D) algorithms, which allows one to resolve the solid-liquid interface as per the desired level of resolution. We discuss the influence of the induced streaming potential on the modification of the Darcy law in connection to transport processes through porous plugs, clays and soils by considering a case-study on Berea sandstone.
On the Angular Width of Diffractive Beam in Anisotropic Media
Lock, Edwin H
2011-01-01
2-D diffraction patterns arising in the far-field region were investigated theoretically for the case, when the plane wave with non collinear group and phase velocities is incident on the wide slit in opaque screen with arbitrary orientation. This investigation was carried out by consideration as an example of magnetostatic surface wave diffraction in tangentially magnetized ferrite slab. It was deduced the universal analytical formula, which one can use to calculate the angular width of diffractive beam in any 2-D anisotropic geometries for the waves of various nature. It was shown, that in 2-D anisotropic geometries this width may be not only more or less then the value L/D (L - wavelength of incident wave, D - length of slit), but it also may be equal to zero in certain conditions.
The multiphase flow and heat transfer in porous media
Starikovicius, V.
2003-01-01
In first part of this work, summaries of traditional Multiphase Flow Model and more recent Multiphase Mixture Model are presented. Attention is being paid to attempts include various heterogeneous aspects into models. In second part, MMM based differential model for two-phase immiscible flow in porous media is considered. A numerical scheme based on the sequential solution procedure and control volume based finite difference schemes for the pressure and saturation-conservation equations is de...
Consolidation of elastic porous media saturated by two immiscible fluids
Tuncay, Kağan; Çorapçıoğlu, M. Yavuz
1996-01-01
A theory is presented to simulate the consolidation of elastic porous media saturated by two immiscible Newtonian fluids. The macroscopic equations, including mass and momentum balance equations and constitutive relations, are obtained by volume averaging the microscale equations. The theory is based on the small deformation assumption. In the microscale, the grains are assumed to be linearly elastic and the fluids are Newtonian. The bulk and shear moduli of the solid matrix are introduced to...
Cell-centered finite volume discretizations for deformable porous media
Nordbotten, Jan Martin
2014-01-01
The development of cell-centered finite volume discretizations for deformation is motivated by the desire for a compatible approach with the discretization of fluid flow in deformable porous media. We express the conservation of momentum in the finite volume sense, and introduce three approximations methods for the cell-face stresses. The discretization method is developed for general grids in one to three spatial dimensions, and leads to a global discrete system of equations for the displace...
Numerical Simulations of Heat Explosion With Convection In Porous Media
Allali, Karam; Bikany, Fouad; Taik, Ahmed; Volpert, Vitaly
2013-01-01
In this paper we study the interaction between natural convection and heat explosion in porous media. The model consists of the heat equation with a nonlinear source term describing heat production due to an exothermic chemical reaction coupled with the Darcy law. Stationary and oscillating convection regimes and oscillating heat explosion are observed. The models with quasi-stationary and unstationary Darcy equation are compared.
Logarithmic diffusion and porous media equations: a unified description
Pedron, I. T.; Mendes, R. S.; Buratta, T. J.; L. C. Malacarne; Lenzi, E. K.
2005-01-01
In this work we present the logarithmic diffusion equation as a limit case when the index that characterizes a nonlinear Fokker-Planck equation, in its diffusive term, goes to zero. A linear drift and a source term are considered in this equation. Its solution has a lorentzian form, consequently this equation characterizes a super diffusion like a L\\'evy kind. In addition is obtained an equation that unifies the porous media and the logarithmic diffusion equations, including a generalized dif...
RADICAL FLOW IN POROUS MEDIA WITH DISPERSION AND ADSORPTION
Institute of Scientific and Technical Information of China (English)
LIU Ci-qun; GUO Bai-qi; SONG Fu-quan; WANG Jin-ying
2004-01-01
The radical transport of chemical concentration in porous media with dispersion and adsorption was studied in this paper. Using Langmuir's adsorption model, the numerical equation of concentration transport was derived. The flows with and without adsorption were simulated and analyzed.Comparison of the obtained solution with the known analytical solution for flow without adsorption shows the presented numerical method is correct and effective, which can be used in reservoir engineering.
Fractal Derivative Model for Air Permeability in Hierarchic Porous Media
Directory of Open Access Journals (Sweden)
Jie Fan
2012-01-01
Full Text Available Air permeability in hierarchic porous media does not obey Fick's equation or its modification because fractal objects have well-defined geometric properties, which are discrete and discontinuous. We propose a theoretical model dealing with, for the first time, a seemingly complex air permeability process using fractal derivative method. The fractal derivative model has been successfully applied to explain the novel air permeability phenomenon of cocoon. The theoretical analysis was in agreement with experimental results.
Pore Scale Simulation of Transport in Porous Media
Fahlke, Jorrit
2008-01-01
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...
Onset of Darcy-Brinkman Convection in a Maxwell Fluid Saturated Anisotropic Porous Layer
Directory of Open Access Journals (Sweden)
S. N. Gaikwad
2016-01-01
Full Text Available In the present study, the onset of Darcy-Brinkman double diffusive convection in a Maxwell fluid-saturated anisotropic porous layer is studied analytically using stability analysis. The linear stability analysis is based on normal technique. The modified Darcy-Brinkmam Maxwell model is used for the momentum equation. The Rayleigh number for stationary, oscillatory and finite amplitude convection is obtained analytically. The effect of the stress relaxation parameter, solute Rayleigh number, Darcy number, Darcy-Prandtl number, Lewis number, mechanical and thermal anisotropy parameters, and normal porosity parameter on the stationary, oscillatory and finite amplitude convection is shown graphically. The nonlinear theory is based on the truncated representation of the Fourier series method and is used to find the heat and mass transfer. The transient behavior of the Nusselt and Sherwood numbers is obtained by solving the finite amplitude equations using the Runge-Kutta method.
Olariu, C. S.; Padurariu, L.; Stanculescu, R.; Baldisserri, C.; Galassi, C.; Mitoseriu, L.
2013-12-01
Anisotropic porous Pb(Zr,Ti)O3 ceramics with various porosity degrees have been studied in order to determine the role of the pore shape and orientation on the low-field dielectric properties. Ceramic samples with formula Pb(Zr0.52Ti0.48)0.976Nb0.024O3 with different porosity degrees (dense, 10%, 20%, 40% vol.) have been prepared by solid state reaction. Taking into consideration the shape and orientation of the pore inclusions, the dielectric properties of porous ceramics have been described by using adapted mixing rules models. Rigorous bounds, derived on the basis on Variational Principle, were used to frame dielectric properties of porous composites. The finite element method (FEM) was additionally used to simulate the dielectric response of the porous composites under various applied fields. Among the few effective medium approximation models adapted for anisotropic oriented inclusions, the best results were obtained in case of needle-like shape inclusions (which do not correspond to the real shape of microstructure inclusions). The general case of Wiener bounds limited well the dielectric properties of anisotropic porous composites in case of parallel orientation. Among the theoretical approaches, FEM technique allowed to simulate the distribution of potential and electric field inside composites and provided a very good agreement between the computed permittivity values and experimental ones.
Statistical fusion of two-scale images of porous media
Mohebi, Azadeh; Fieguth, Paul; Ioannidis, Marios A.
2009-11-01
The reconstruction of the architecture of void space in porous media is a challenging task, since porous media contain pore structures at multiple scales. Whereas past methods have been limited to producing samples with matching statistical behavior, the patterns of grey-level values in a measured sample actually say something about the unresolved details, thus we propose a statistical fusion framework for reconstructing high-resolution porous media images from low-resolution measurements. The proposed framework is based on a posterior sampling approach in which information obtained by low-resolution (MRI or X-ray) measurements is combined with prior models inferred from high-resolution microscopic data, typically 2D. In this paper, we focus on two-scale reconstruction tasks in which the measurements resolve only the large scale structures, leaving the small-scale to be inferred. The evaluation of the results generated by the proposed method shows the strong ability of the proposed method in reconstructing fine-scale structures positively correlated with the underlying ground truth. Comparing our method with the recent method of Okabe and Blunt [12], in which the measurements are also used in the reconstruction, we conclude that our method is more robust to the resolution of the measurement, and more closely matches the underlying fine-scale field.
Dendrite Suppression by Shock Electrodeposition in Charged Porous Media
Han, Ji-Hyung; Wang, Miao; Bai, Peng; Brushett, Fikile R.; Bazant, Martin Z.
2016-06-01
It is shown that surface conduction can stabilize electrodeposition in random, charged porous media at high rates, above the diffusion-limited current. After linear sweep voltammetry and impedance spectroscopy, copper electrodeposits are visualized by scanning electron microscopy and energy dispersive spectroscopy in two different porous separators (cellulose nitrate, polyethylene), whose surfaces are modified by layer-by-layer deposition of positive or negative charged polyelectrolytes. Above the limiting current, surface conduction inhibits growth in the positive separators and produces irregular dendrites, while it enhances growth and suppresses dendrites behind a deionization shock in the negative separators, also leading to improved cycle life. The discovery of stable uniform growth in the random media differs from the non-uniform growth observed in parallel nanopores and cannot be explained by classic quasi-steady “leaky membrane” models, which always predict instability and dendritic growth. Instead, the experimental results suggest that transient electro-diffusion in random porous media imparts the stability of a deionization shock to the growing metal interface behind it. Shock electrodeposition could be exploited to enhance the cycle life and recharging rate of metal batteries or to accelerate the fabrication of metal matrix composite coatings.
Particle retention in porous media: Applications to water injectivity decline
Energy Technology Data Exchange (ETDEWEB)
Wennberg, Kjell Erik
1998-12-31
This thesis studies the problem of migration and deposition of colloidal particles within porous media, theoretically and by computerized simulation. Special emphasis is put on the prediction of injectivity decline in water injection wells due to inherent particles in the injection water. The study of particle deposition within porous media requires a correct prediction of the deposition rate or filtration coefficient. A thorough review of the modeling approaches used in the past are combined with new ideas in order to arrive at an improved model for the prediction of the filtration coefficient. A new way of determining the transition time for the dominant deposition mechanism to change from internal deposition to external cake formation is proposed. From this fundamental theory, equations are given for water injectivity decline predictions. A computer program called WID for water injectivity decline predictions was developed. Using water quality, formation properties, injection rate/pressure and completion information as input, WID predicts decline in vertical and horizontal injection wells with openhole, perforated and fractured completions. The calculations agree fairly well with field data; in some cases the agreement is excellent. A poor match in a few cases indicates that more mechanisms may be responsible for injectivity decline than those presently accounted for by the simulator. The second part of the study deals with a theoretical investigation of the multi-dimensional nature of particle deposition in porous media. 112 refs., 100 figs., 9 tabs.
Solute transport through porous media using asymptotic dispersivity
Indian Academy of Sciences (India)
P K Sharma; Teodrose Atnafu Abgaze
2015-08-01
In this paper, multiprocess non-equilibrium transport equation has been used, which accounts for both physical and chemical non-equilibrium for reactive transport through porous media. An asymptotic distance dependent dispersivity is used to embrace the concept of scale-dependent dispersion for solute transport in heterogeneous porous media. Semi-analytical solution has been derived of the governing equations with an asymptotic distance dependent dispersivity by using Laplace transform technique and the power series method. For application of analytical model, we simulated observed experimental breakthrough curves from 1500 cm long soil column experiments conducted in the laboratory. The simulation results of break-through curves were found to deviate from the observed breakthrough curves for both mobile–immobile and multiprocess non-equilibrium transport with constant dispersion models. However, multiprocess non-equilibrium with an asymptotic dispersion model gives better fit of experimental breakthrough curves through long soil column and hence it is more useful for describing anomalous solute transport through hetero-geneous porous media. The present model is simpler than the stochastic numerical method.
An analysis of seismic attenuation in random porous media
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
The attenuation of seismic wave in rocks has been one of the interesting research topics, but till now no poroelasticity models can thoroughly explain the strong attenuation of wave in rocks. In this paper, a random porous medium model is designed to study the law of wave propagation in complex rocks based on the theory of Biot poroelasticity and the general theory of stochastic process. This model sets the density of grain, porosity, permeability and modulus of frame as random parameters in space, and only one fluid infiltrates in rocks for the sake of better simulation effect in line with real rocks in earth strata. Numerical simulations are implemented. Two different inverse quality factors of fast P-wave are obtained by different methods to assess attenuation through records of virtual detectors in wave field (One is amplitude decay method in time domain and the other is spectral ratio method in frequency domain). Comparing the attenuation results of random porous medium with those of homogeneous porous medium, we conclude that the attenuation of seismic wave of homogeneous porous medium is far weaker than that of random porous medium. In random porous media, the higher heterogeneous level is, the stronger the attenuation becomes, and when heterogeneity σ = 0.15 in simulation, the attenuation result is consistent with that by actual observation. Since the central frequency (50 Hz) of source in numerical simulation is in earthquake band, the numerical results prove that heterogeneous porous structure is one of the important factors causing strong attenuation in real stratum at intermediate and low frequency.
Djebbi, Ramzi
2013-08-19
Anisotropy is an inherent character of the Earth subsurface. It should be considered for modeling and inversion. The acoustic VTI wave equation approximates the wave behavior in anisotropic media, and especially it\\'s kinematic characteristics. To analyze which parts of the model would affect the traveltime for anisotropic traveltime inversion methods, especially for wave equation tomography (WET), we drive the sensitivity kernels for anisotropic media using the VTI acoustic wave equation. A Born scattering approximation is first derived using the Fourier domain acoustic wave equation as a function of perturbations in three anisotropy parameters. Using the instantaneous traveltime, which unwraps the phase, we compute the kernels. These kernels resemble those for isotropic media, with the η kernel directionally dependent. They also have a maximum sensitivity along the geometrical ray, which is more realistic compared to the cross-correlation based kernels. Focusing on diving waves, which is used more often, especially recently in waveform inversion, we show sensitivity kernels in anisotropic media for this case.
Bound dipole solitary solutions in anisotropic nonlocal self-focusing media
DEFF Research Database (Denmark)
Mamaev, A.V.; Zozulya, A.A.; Mezentsev, V.K.;
1997-01-01
We find and analyze bound dipole solitary solutions in media with anisotropic nonlocal photorefractive material response. The dipole solutions consist of two elliptically shaped Gaussian-type beams separated by several diameters, and with a pi phase shift between their fields. Spatial evolution o...
Calibration of Gurson-type models for porous sheet metals with anisotropic non-quadratic plasticity
Gologanu, M.; Kami, A.; Comsa, D. S.; Banabic, D.
2016-08-01
The growth and coalescence of voids in sheet metals are not only the main active mechanisms in the final stages of fracture in a necking band, but they also contribute to the forming limits via changes in the normal directions to the yield surface. A widely accepted method to include void effects is the development of a Gurson-type model for the appropriate yield criterion, based on an approximate limit analysis of a unit cell containing a single spherical, spheroidal or ellipsoidal void. We have recently [2] obtained dissipation functions and Gurson-type models for porous sheet metals with ellipsoidal voids and anisotropic non-quadratic plasticity, including yield criteria based on linear transformations (Yld91 and Yld2004-18p) and a pure plane stress yield criteria (BBC2005). These Gurson-type models contain several parameters that depend on the void and cell geometries and on the selected yield criterion. Best results are obtained when these key parameters are calibrated via numerical simulations using the same unit cell and a few representative loading conditions. The single most important such loading condition corresponds to a pure hydrostatic macroscopic stress (pure pressure) and the corresponding velocity field found during the solution of the limit analysis problem describes the expansion of the cavity. However, for the case of sheet metals, the condition of plane stress precludes macroscopic stresses with large triaxiality or ratio of mean stress to equivalent stress, including the pure hydrostatic case. Also, pure plane stress yield criteria like BBC2005 must first be extended to 3D stresses before attempting to develop a Gurson-type model and such extensions are purely phenomenological with no due account for the out- of-plane anisotropic properties of the sheet. Therefore, we propose a new calibration method for Gurson- type models that uses only boundary conditions compatible with the plane stress requirement. For each such boundary condition we use
Modeling imbibition of liquids into rigid and swelling porous media
Masoodi, Reza
In porous media studies, imbibition is the spontaneous movement of a liquid into a porous medium under the influence of capillary forces. It is also known by the name wicking, and can sometimes be aided by an external pressure, as in the case of forced infiltration of liquid polymers into a bed of fibermats. In this study, the imbibition of liquids into porous media in important engineering applications is studied. A relatively new approach of using the single-phase flow behind a clearly-defined liquid front in a porous medium has been adopted in this work to model imbibition or wicking. Such an approach employs Darcy's law in conjunction with the continuity equation to model the liquid flow behind the front. First the modeling of liquid flow in polymer wicks is undertaken. A new formula to predict the capillary suction-pressure at the liquid fronts in commercial wicks made of sintering the polymer beads was proposed. Later, a more general formula was derived and verified for estimating the capillary suction pressure in any kind of porous substance. We compared the performance of the proposed Darcy's-law based approach with that of the Lucas-Washburn equation; some new methods were suggested to improve the accuracy of these two dominant methods for modeling the liquid transport in aforementioned wicks. Our Darcy's law based modeling approach is superior to the previous Washburn Equation based approaches as the former can be easily extended to 2-D and 3-D unlike the latter. The 3-D liquid flow in the wicks was studied numerically using PORE-FLOW(c), an in-house computer program to model porous-media flows. For the first time, the finite element/control volume (FE/CV) algorithm is employed to solve the moving- boundary problem encountered in wicking. A good validation is achieved against the 1-D wicking-flow analytical solution as well as a 3-D wicking experiment involving a wick with two different cross-sections. A special case of wicking, in which both the external
Diffusion with condensation and evaporation in porous media
International Nuclear Information System (INIS)
Vapor phase transport in porous media is important in a number of environmental and industrial processes: soil moisture transport, vapor phase transport in the vadose zone, transport in the vicinity of buried nuclear waste, and industrial processes such as drying. The diffusion of water vapor in a packed bed containing residual liquid is examined experimentally. The objective is to quantify the effect of enhanced vapor diffusion resulting from evaporation/condensation in porous media subjected to a temperature gradient. Isothermal diffusion experiments in free-space were conducted to qualify the experimental apparatus and techniques. For these experiments measured diffusion coefficients are within 3.6% of those reported in the literature for the temperature range from 25 C to 40 C. Isothermal experiments in packed beds of glass beads were used to determine the tortuosity coefficient resulting in τ = 0.78 ± 0.028, which is also consistent with previously reported results. Nonisothermal experiments in packed beds in which condensation occurs were conducted to examine enhanced vapor diffusion. The interpretation of the results for these experiments is complicated by a gradual, but continuous, build-up of condensate in the packed beds during the course of the experiment. Results indicate diffusion coefficients which increase as a function of saturation resulting in enhancement of the vapor-phase transport by a factor of approximately four compared to a dry porous medium
Drying patterns of porous media containing wettability contrasts.
Shokri, N; Or, D
2013-02-01
Porous media containing sharp wettability discontinuities may occur in natural systems due to depositional processes, accumulation of organic layers or modification of soil wettability following intense forest fires all of which are known to significantly modify water flow and transport processes. We studied evaporation from sand columns containing hydraulically-interacting domains with sharp wettability contrasts. We employed neutron transmission technique to map liquid phase dynamics during evaporation, and conducted laboratory experiments to evaluate evaporative fluxes affected by interactions across wettability contrast. We explained the preferential drying front displacement in the hydrophobic domain and the spatial extent of capillary flow supporting the vaporization plane using a physically-based model. The model provides description of observed liquid phase patterns and dynamics observed in neutron radiography measurements and evaporative fluxes from laboratory experiments. Our results provide new insights into evaporation induced capillary exchange and preferential liquid phase distribution during evaporation from hydraulically interacting vertical porous domains with differing wettability properties and offer opportunities for design of selectively drying of porous media in natural and engineered systems. PMID:23123032
Measurement of Interfacial Area Production and Permeability within Porous Media
Energy Technology Data Exchange (ETDEWEB)
Crandall, Dustin; Ahmadi, Goodarz; Smith, Duane H.
2010-01-01
An understanding of the pore-level interactions that affect multi-phase flow in porous media is important in many subsurface engineering applications, including enhanced oil recovery, remediation of dense non-aqueous liquid contaminated sites, and geologic CO2 sequestration. Standard models of two-phase flow in porous media have been shown to have several shortcomings, which might partially be overcome using a recently developed model based on thermodynamic principles that includes interfacial area as an additional parameter. A few static experimental studies have been previously performed, which allowed the determination of static parameters of the model, but no information exists concerning the interfacial area dynamic parameters. A new experimental porous flow cell that was constructed using stereolithography for two-phase gas-liquid flow studies was used in conjunction with an in-house analysis code to provide information on dynamic evolution of both fluid phases and gas-liquid interfaces. In this paper, we give a brief introduction to the new generalized model of two-phase flow model and describe how the stereolithography flow cell experimental setup was used to obtain the dynamic parameters for the interfacial area numerical model. In particular, the methods used to determine the interfacial area permeability and production terms are shown.
A reconstruction method of porous media integrating soft data with hard data
Institute of Scientific and Technical Information of China (English)
LU DeTang; ZHANG Ting; YANG JiaQing; LI DaoLun; KONG XiangYan
2009-01-01
The three-dimensional reconstruction of porous media is of great significance to the research of mechanisms of fluid flow. The real three-dimensional structural data of porous media are helpful to describe the irregular topologic structures in porous media. The reconstruction of porous media will be inaccurate while only hard data or no conditional data are available. Reconstructed results can be more accurate, using soft data during reconstruction. Integrating soft data with hard data, a method based on multiple-point geostatistics (MPS) is proposed to reconstruct three-dimensional structures of porous media. The variogram curves and permeability, computed by lattice Boltzmann method (LBM), of the reconstructed images and the target image obtained from real volume data were compared, showing that the structural characteristics of reconstructed porous media using both soft data and hard data as conditional data are most similar to those of real volume data.
The kinetics of ice-lens growth in porous media
Style, Robert W.
2012-01-09
Abstract We analyse the growth rate of segregated ice (ice lenses) in freezing porous media. For typical colloidal materials such as soils we show that the commonly employed Clapeyron equation is not valid macroscopically at the interface between the ice lens and the surrounding porous medium owing to the viscous dynamics of flow in premelted films. The flow in these films gives rise to an \\'interfacial resistance\\' to flow towards the growing ice which causes a significant drop in predicted ice-growth (heave) rates. This explains why many previous models predict ice-growth rates that are much larger than those seen in experiments. We derive an explicit formula for the ice-growth rate in a given porous medium, and show that this only depends on temperature and on the external pressures imposed on the freezing system. This growth-rate formula contains a material-specific function which can be calculated (with knowledge of the geometry and material of the porous medium), but which is also readily experimentally measurable. We apply the formula to plate-like particles, and show that the results can be matched with previous experimental data. Finally we show how the interfacial resistance explains the observation that the maximum heave rate in soils occurs in medium-grained particles such as silts, while heave rates are smaller for fine-and coarse-grained particles. © 2012 Cambridge University Press.
Converted-wave Seismology in Anisotropic Media Revisited, Part I： Basic Theory
Institute of Scientific and Technical Information of China (English)
XiangyangLi; JianxinYuan
2005-01-01
We have developed new basic theories for calculating the conversion point and the travel time of the P-SV converted wave (C-wave) in anisotropic, inhomogeneous media. This enables the use of conventional procedures such as semblance analysis, Dix-type model building and Kirchhoff summation, to implement anisotropic processing, and makes anisotropic processing affordable. Here we present these new developments in two parts: basic theory and application to velocity analysis and parameter estimation. This part deals with the basic theory, including both conversion-point calculation and moveout analysis.Existing equations for calculating the PS-wave (C-wave) conversion point in layered media with vertical transverse isotropy (VTI) are strictly limited to offsets about half the reflector depth (an offset-depth ratio, x/z, of 0.5), and those for calculating the C-wave traveltimes are limited to offsets equal to the reflector depth (x/z=1.0). In contrast, the new equations for calculating the conversion-point extend into offsets about three-times the reflector depth (x/z=3.0), those for calculating the C-wave traveltimes extend into offsets twice the reflector depth (x/z=2.0). With the improved accuracy, the equations can help in C-wave data processing and parameter estimation in anisotropic, inhomogeneous media.
An electrical conductivity model for fractal porous media
Wei, Wei; Cai, Jianchao; Hu, Xiangyun; Han, Qi
2015-06-01
Archie's equation is an empirical electrical conductivity-porosity model that has been used to predict the formation factor of porous rock for more than 70 years. However, the physical interpretation of its parameters, e.g., the cementation exponent m, remains questionable. In this study, a theoretical electrical conductivity equation is derived based on the fractal characteristics of porous media. The proposed model is expressed in terms of the tortuosity fractal dimension (DT), the pore fractal dimension (Df), the electrical conductivity of the pore liquid, and the porosity. The empirical parameter m is then determined from physically based parameters, such as DT and Df. Furthermore, a distinct interrelationship between DT and Df is obtained. We find a reasonably good match between the predicted formation factor by our model and experimental data.
High-precision synthetic computed tomography of reconstructed porous media
Hilfer, R.; Zauner, Th.
2011-12-01
Multiscale simulation of transport in disordered and porous media requires microstructures covering several decades in length scale. X-ray and synchrotron computed tomography are presently unable to resolve more than one decade of geometric detail. Recent advances in pore scale modeling [Biswal, Held, Khanna, Wang, and Hilfer, Phys. Rev. E PLEEE81539-375510.1103/PhysRevE.80.041301 80, 041301 (2009)] provide strongly correlated microstructures with several decades in microstructural detail. A carefully calibrated microstructure model for Fontainebleau sandstone has been discretized into a suite of three-dimensional microstructures with resolutions from roughly 128 μm down to roughly 500 nm. At the highest resolution the three-dimensional image consists of 327683=35184372088832 discrete cubic volume elements with gray values between 0 and 216. To the best of our knowledge, this synthetic image is the largest computed tomogram of a porous medium available at present.
Anomalous dynamics of capillary rise in porous media
Shikhmurzaev, Yulii D.
2012-07-09
The anomalous dynamics of capillary rise in a porous medium discovered experimentally more than a decade ago is described. The developed theory is based on considering the principal modes of motion of the menisci that collectively form the wetting front on the Darcy scale. These modes, which include (i) dynamic wetting mode, (ii) threshold mode, and (iii) interface depinning process, are incorporated into the boundary conditions for the bulk equations formulated in the regular framework of continuum mechanics of porous media, thus allowing one to consider a general case of three-dimensional flows. The developed theory makes it possible to describe all regimes observed in the experiment, with the time spanning more than four orders of magnitude, and highlights the dominant physical mechanisms at different stages of the process. © 2012 American Physical Society.
Ferrofluid magnetoviscous control of wall flow channeling in porous media
Institute of Scientific and Technical Information of China (English)
Fa(ic)al Larachi; Damien Desvigne
2007-01-01
We analyzed the phenomenon of ferrofluid magnetoviscosity in high-permeability wall-region non-magnetic porous media of the Müller kind.After upscaling the pore-level ferrohydrodynamic model, we obtained a simplified volume-average zero-order axisymmetric model for non-Darcy non-turbulent flow of steady-state isothermal incompressible Newtonian ferrofluids through a porous medium experiencing external constant bulk-flow oriented gradient magnetic field, ferrofluid self-consistent demagnetizing field and induced magnetic field in the solid. The model was explored in contexts plagued by wall flow maldistribution due to low column-to-particle diameter ratios. It was shown that for proper magnetic field arrangement, wall channeling can be reduced by inflating wall flow resistance through magnetovisco-thickening and Kelvin body force density which reroute a fraction of wall flow towards bed core.
Steady Counterflow he II Heat Transfer Through Porous Media
Dalban-Canassy, M.; Van Sciver, S. W.
2010-04-01
We present steady state counterflow measurements performed on porous samples saturated in He II. The experiment is composed of a vacuum insulated open channel whose top extremity is closed to a Minco® heater. The temperature and pressure differences across the plug are measured by two germanium TTR-G Microsensors® thermometers and a Validyne DP10-20 differential pressure sensor. Applied heat fluxes range up to 0.5 kW/m2 of sample cross section. Measurements were performed at temperatures ranging from 1.7 to 2.1 K on highly anisotropic samples provided by Composite Technology Development Inc.: circular pellets (3.08 mm thick and 28.58 mm in diameter) of 20 compressed layers of pre-impregnated woven magnet insulation. In the laminar regime, the permeability is estimated from the pressure drop measurements for comparison with room temperature data. In the turbulent regime, the model based on tortuosity developed previously fails to describe the heat transfer behavior of He II in this type of porous medium.
Direct numerical simulation of inertial flows in porous media
Apte, S.; Finn, J.; Wood, B. D.
2010-12-01
At modest flow rates (10 ≤ Re ≤ 300) through porous media and packed beds, fluid inertia can result in complex steady and unsteady recirculation regions, dependent on the local pore geometry. Body fitted CFD is a broadly used design and analysis tool for flows in porous media and packed bed type reactors. Unfortunately, the inherent complexities of porous media make unstructured mesh generation a difficult and time consuming step in the simulation process. To accurately capture the inertial dynamics using high-fidelity direct simulations, body fitted meshes must be high quality and sufficiently refined. We present methods to parameterize and simplify mesh generation for packed beds, with an eye toward obtaining efficient mesh independence for Reynolds numbers in the inertial and unsteady regimes. The crux of mesh generation for packed beds is dealing with sphere-sphere or sphere-wall contact points, where a geometric singularity exists. To handle the sphere-sphere and sphere-wall contact points, we use a fillet bridge model, in which every pair of contacting entities are bridged by a fillet, eliminating a small fluid region near the contact point. This results in a continuous surface mesh which does not require resizing of the spheres and can accommodate prism cells for improved boundary layer resolution. A second order accurate, parallel, incompressible flow solver [Moin and Apte, AIAA J. 2006] is used to simulate flow through three different sphere packings: a periodic simple cubic packing, a wall bounded hexagonal close packing, and a randomly packed tube. Mesh independence is assessed using several measures including Ergun pressure drop coefficients, viscous and pressure components of drag force, kinetic energy, kinetic energy dissipation and interstitial velocity profiles. The results of these test cases are used to determine the feasibility of accurate and very large scale simulations of flow through a randomly packed bed of 103 pores. Preliminary results
Description of a Furnace for the Creation of Anisotropic Porous Metals
Energy Technology Data Exchange (ETDEWEB)
Gutsch, Thomas; Miszkiel, Mark; Schmale, David T.
1999-05-01
A furnace has been built for the purpose of producing anisotropic porous metals through solid-gas eutectic solidification. This process allows control of continuously formed anisotropic pores in metals and was discovered at the State Metallurgical Academic' University in Dnepropetrovsk Ukraine. The process incorporates hydrogen gas within the metal as it solidifies from the molten state. Metals which do not form hydrides, including iron, nickel, aluminum, copper and others can be formed in this manner. The furnace is housed within a ~.64 meter³ (30 ft³) ASME code stamped cylindrical stainless steel vacuum/pressure vessel. The vessel is a water chilled vertical cylinder with removable covers at the top and bottom. It can be evacuated to 20 mTorr or pressurized to 5.5 MPa (800 psi). A charge of 2700 cc (167 in³) of molten metal can be melted in a crucible in the upper portion within a watercooled 30 cm (12 in.) ID induction coil. A 175 kW Inductotherm power source energizes the coil. Vertical actuation of a ceramic stopper rod allows the molten metal to be tapped into a solidification mold beneath the melting crucible. The cylindrical mold rests on a water cooled copper base inducing directional solidification from the bottom. Mixtures of hydrogen and argon gases are introduced during the process. The system is remotely controlled and located in a structure with frangible walls specially designed for possible ambient pressure excursions as a result of equipment failure. This paper includes a general description of the furnace and operating procedure and a detailed description of the control, monitoring and interlock systems.
Simulation of impaction filtration of aerosol droplets in porous media
Ghazaryan, Lilya; Lopez Penha, David J.; Geurts, Bernard J.; Stolz, Steffen; Winkelmann, Christoph; Pereira, J.C.F.; Sequeira, A.; Pereira, J. M. C.
2010-01-01
We report on the development of a method to simulate from first principles the particle filtration efficiency of filters that are composed of structured porous media. We assume that the ratio of particle density to the fluid density is high. We concentrate on the motion of the particles in a laminar flow and quantify the role of inertial effects on the filtration of an ensemble of particles. We adopt the Euler-Lagrange approach, distinguishing a flow field in which the motion of a large numbe...
Bacteria transport through porous media. Annual report, December 31, 1984
Energy Technology Data Exchange (ETDEWEB)
Yen, T.F.
1986-09-01
The following five chapters in this report have been processed separately for inclusion in the Energy Data Base: (1) theoretical model of convective diffusion of motile and non-motile bacteria toward solid surfaces; (2) interfacial electrochemistry of oxide surfaces in oil-bearing sands and sandstones; (3) effects of sodium pyrophosphate additive on the ''huff and puff''/nutrient flooding MEOR process; (4) interaction of Escherichia coli B, B/4, and bacteriophage T4D with Berea sandstone rock in relation to enhanced oil recovery; and (5) transport of bacteria in porous media and its significance in microbial enhanced oil recovery.
Porous Media Approach for Modeling Closed Cell Foam
Ghosn, Louis J.; Sullivan, Roy M.
2006-01-01
In order to minimize boil off of the liquid oxygen and liquid hydrogen and to prevent the formation of ice on its exterior surface, the Space Shuttle External Tank (ET) is insulated using various low-density, closed-cell polymeric foams. Improved analysis methods for these foam materials are needed to predict the foam structural response and to help identify the foam fracture behavior in order to help minimize foam shedding occurrences. This presentation describes a continuum based approach to modeling the foam thermo-mechanical behavior that accounts for the cellular nature of the material and explicitly addresses the effect of the internal cell gas pressure. A porous media approach is implemented in a finite element frame work to model the mechanical behavior of the closed cell foam. The ABAQUS general purpose finite element program is used to simulate the continuum behavior of the foam. The soil mechanics element is implemented to account for the cell internal pressure and its effect on the stress and strain fields. The pressure variation inside the closed cells is calculated using the ideal gas laws. The soil mechanics element is compatible with an orthotropic materials model to capture the different behavior between the rise and in-plane directions of the foam. The porous media approach is applied to model the foam thermal strain and calculate the foam effective coefficient of thermal expansion. The calculated foam coefficients of thermal expansion were able to simulate the measured thermal strain during heat up from cryogenic temperature to room temperature in vacuum. The porous media approach was applied to an insulated substrate with one inch foam and compared to a simple elastic solution without pore pressure. The porous media approach is also applied to model the foam mechanical behavior during subscale laboratory experiments. In this test, a foam layer sprayed on a metal substrate is subjected to a temperature variation while the metal substrate is
Okazaki, T.; Oshiman, N.; Yoshimura, R.
2016-11-01
Inferring geoelectric dimensionality (1D, 2D or 3D) and directionality (strike directions) from the impedance tensor is a basic procedure in magnetotelluric data processing. Given that electrical anisotropy is increasingly recognized in observations, it is valuable to understand the imprint of anisotropy in these analyses. In this paper, we analytically investigate the estimation of strike directions based on rotational invariants in 1D anisotropic layered media. We first show that if anisotropy axes are identical in all anisotropic layers, the estimated strike coincides with that direction. We then derive an analytical formula of the strike angle at long periods for general anisotropic layers with an isotropic basement. This formula shows a clear physical interpretation that the strike angle points where the conductance integrated along depth takes a maximum value.
Ferrage, Eric; Hubert, Fabien; Tertre, Emmanuel; Delville, Alfred; Michot, Laurent J.; Levitz, Pierre
2015-06-01
Swelling clay minerals play a key role in the control of water and pollutant migration in natural media such as soils. Moreover, swelling clay particles' orientational properties in porous media have significant implications for the directional dependence of fluid transfer. Herein we investigate the ability to mimic the organization of particles in natural swelling-clay porous media using a three-dimensional sequential particle deposition procedure [D. Coelho, J.-F. Thovert, and P. M. Adler, Phys. Rev. E 55, 1959 (1997), 10.1103/PhysRevE.55.1959]. The algorithm considered is first used to simulate disk packings. Porosities of disk packings fall onto a single master curve when plotted against the orientational scalar order parameter value. This relation is used to validate the algorithm used in comparison with existing ones. The ellipticity degree of the particles is shown to have a negligible effect on the packing porosity for ratios ℓa/ℓb less than 1.5, whereas a significant increase in porosity is obtained for higher values. The effect of the distribution of the geometrical parameters (size, aspect ratio, and ellipticity degree) of particles on the final packing properties is also investigated. Finally, the algorithm is used to simulate particle packings for three size fractions of natural swelling-clay mineral powders. Calculated data regarding the distribution of the geometrical parameters and orientation of particles in porous media are successfully compared with experimental data obtained for the same samples. The results indicate that the obtained virtual porous media can be considered representative of natural samples and can be used to extract properties difficult to obtain experimentally, such as the anisotropic features of pore and solid phases in a system.
Ferrage, Eric; Hubert, Fabien; Tertre, Emmanuel; Delville, Alfred; Michot, Laurent J; Levitz, Pierre
2015-06-01
Swelling clay minerals play a key role in the control of water and pollutant migration in natural media such as soils. Moreover, swelling clay particles' orientational properties in porous media have significant implications for the directional dependence of fluid transfer. Herein we investigate the ability to mimic the organization of particles in natural swelling-clay porous media using a three-dimensional sequential particle deposition procedure [D. Coelho, J.-F. Thovert, and P. M. Adler, Phys. Rev. E 55, 1959 (1997)]. The algorithm considered is first used to simulate disk packings. Porosities of disk packings fall onto a single master curve when plotted against the orientational scalar order parameter value. This relation is used to validate the algorithm used in comparison with existing ones. The ellipticity degree of the particles is shown to have a negligible effect on the packing porosity for ratios ℓ(a)/ℓ(b) less than 1.5, whereas a significant increase in porosity is obtained for higher values. The effect of the distribution of the geometrical parameters (size, aspect ratio, and ellipticity degree) of particles on the final packing properties is also investigated. Finally, the algorithm is used to simulate particle packings for three size fractions of natural swelling-clay mineral powders. Calculated data regarding the distribution of the geometrical parameters and orientation of particles in porous media are successfully compared with experimental data obtained for the same samples. The results indicate that the obtained virtual porous media can be considered representative of natural samples and can be used to extract properties difficult to obtain experimentally, such as the anisotropic features of pore and solid phases in a system.
Ferrage, Eric; Hubert, Fabien; Tertre, Emmanuel; Delville, Alfred; Michot, Laurent J; Levitz, Pierre
2015-06-01
Swelling clay minerals play a key role in the control of water and pollutant migration in natural media such as soils. Moreover, swelling clay particles' orientational properties in porous media have significant implications for the directional dependence of fluid transfer. Herein we investigate the ability to mimic the organization of particles in natural swelling-clay porous media using a three-dimensional sequential particle deposition procedure [D. Coelho, J.-F. Thovert, and P. M. Adler, Phys. Rev. E 55, 1959 (1997)]. The algorithm considered is first used to simulate disk packings. Porosities of disk packings fall onto a single master curve when plotted against the orientational scalar order parameter value. This relation is used to validate the algorithm used in comparison with existing ones. The ellipticity degree of the particles is shown to have a negligible effect on the packing porosity for ratios ℓ(a)/ℓ(b) less than 1.5, whereas a significant increase in porosity is obtained for higher values. The effect of the distribution of the geometrical parameters (size, aspect ratio, and ellipticity degree) of particles on the final packing properties is also investigated. Finally, the algorithm is used to simulate particle packings for three size fractions of natural swelling-clay mineral powders. Calculated data regarding the distribution of the geometrical parameters and orientation of particles in porous media are successfully compared with experimental data obtained for the same samples. The results indicate that the obtained virtual porous media can be considered representative of natural samples and can be used to extract properties difficult to obtain experimentally, such as the anisotropic features of pore and solid phases in a system. PMID:26172708
Model of anisotropic nonlinearity in self-defocusing photorefractive media.
Barsi, C; Fleischer, J W
2015-09-21
We develop a phenomenological model of anisotropy in self-defocusing photorefractive crystals. In addition to an independent term due to nonlinear susceptibility, we introduce a nonlinear, non-separable correction to the spectral diffraction operator. The model successfully describes the crossover between photovoltaic and photorefractive responses and the spatially dispersive shock wave behavior of a nonlinearly spreading Gaussian input beam. It should prove useful for characterizing internal charge dynamics in complex materials and for accurate image reconstruction through nonlinear media.
A recipe for practical full waveform inversion in anisotropic media
Alkhalifah, Tariq Ali
2014-03-28
In representing the most common (first-order influence, and gravity induced) acoustic anisotropy, transversely isotropic with a vertical symmetry direction (VTI) medium, with the P-wave normal moveout velocity, delta, and eta, we obtain a perturbation radiation pattern that has limited tradeoff between the parameters. Since delta is weakly resolvable from the kinematics of wave propagation, we can use it to play the role that density plays in improving the data fit for an imperfect physical model that ignores the elastic nature of the Earth. An FWI scheme that starts from diving waves would benefit from representing the acoustic VTI model with the P-wave horizontal velocity, eta, and epsilon. In this representation, the diving waves will help us first resolve the horizontal velocity, and then reflections, if the nonlinearity is properly handled, could help us resolve eta, while epsilon comes at the end to improve the amplitude fit (instead of the density). The model update wavelength for acoustic anisotropic FWI is very much similar to that experienced for the isotropic case. Copyright © 2014 by the European Association of Geoscientists & Engineers. All rights reserved.
Experimental study on moving boundaries of fluid flow in porous media
Institute of Scientific and Technical Information of China (English)
ZHOU HongWei; ZHANG YaHeng; LI AiMin; QIU DaYong
2008-01-01
Researches on the boundary shape of fluid flow in porous media play an important role in engineering practices,such as petroleum exploitation,nuclear waste disposal and groundwater contamination.In this paper,six types of artificial porous samples (emery jade) with different porosities are manufactured.With the background of slow flow in porous media,laboratory experiments are carried out by observing the movement of five types of fluids with different dynamic viscosities in various types of porous media.A digital video recorder is employed to record the complete process of the fluid flow in the porous media.Based on the digital photos of the moving boundaries of fluid flow in porous media,the average displacement and fractal dimension of the moving boundary are estimated for different combinations of porosity and dynamic viscosity.Moreover,the evolution behavior of the average velocity and fractal dimension of the moving boundary with time is known.The statistical relations of the average velocity,the fractal dimension of the moving boundary and the porosity of porous media and the dynamic vis-cosity of fluids are proposed in this paper.It is shown that the front shape of the moving boundary of fluid flow in porous media is an integrated result of the porosity of porous media and the dynamic viscosity of fluids.
Numerical method for computing flow through partially saturated porous media
Eaton, R. R.
This paper discusses the development of the finite element computer code SAGUARO which calculates the two-dimensional flow of mass and energy through porous media. The media may be saturated or partially saturated. SAGUARO solves the parabolic time-dependent mass transport equation which accounts for the presence of partially saturated zones through the use of highly non-linear material characteristic curves. The energy equation accounts for the possibility of partially-saturated regions by adjusting the thermal capacitances and thermal conductivities according to the volume fraction of water present in the local pores. The code capabilities are demonstrated through the presentation of a sample problem involving the one dimensional calculation of simultaneous energy transfer and water infiltration into partially saturated hard rock.
Towards a porous media model of the human lung
DeGroot, Christopher T.; Straatman, Anthony G.
2012-05-01
In this article, progress towards building a complete porous media model of the human lung is discussed. While the recent trend in computational fluid dynamics studies of airflow in the human lung has been to continually increase the size and detail of the airway tree under consideration, it is proposed in this work that simulating flow in the human lung as a coupled fluid-porous system is an effective method to simulate the flow in the whole lung. Under the proposed modeling paradigm, a truncated airway tree constitutes a fluid region which is coupled to a porous region that represents the remainder of the lung volume, containing small airways and alveoli. The first part of this work describes pore-level simulations conducted in an alveolated duct geometry, which are present in large quantities in the human lung, to determine its permeability. Next, volume-averaged simulations incorporating the results of the pore-level simulations and using a realistic lung geometry based on computed tomography images are discussed along with future directions for this work.
Physical modelling of elastic anisotropy in porous media
Energy Technology Data Exchange (ETDEWEB)
Furre, Anne-Kari
1997-12-31
During the last decades, anisotropy has become increasingly interesting in hydrocarbon prospecting. Knowledge of anisotropy in the subsurface can improve reservoir production and data interpretation. This thesis presents experimental studies of three different artificial anisotropic media: layered materials, isotropic matrix with stress-induced fractures, and layered media with controlled crack patterns at an oblique angle relative to layering. Layered media were constructed by varying grain size distributions for different layers, which resulted in acoustic and permeability anisotropy. The thin layer materials could be described by Backus modelling provided the wavelength was much larger than the layer periods. Frequency dependent scattering was observed for waves travelling normal to the layers. Saturated wave velocities were consistent with transverse isotropic Biot theory, but because the permeability anisotropy was small, no flow dependent attenuation anisotropy was observed. When sandstones were cemented under stress and then released, to simulate a vertical core or uplift process, predominantly horizontal cracks developed in the samples. On reloading to the cementing stress level, the velocities were below the initial values, which supports the theories of crack growth. In further triaxial tests on the same material a stress-dependent anisotropy occurred similar to what is often seen in natural samples taken from large depths. 70 refs., 200 figs., 56 tabs.
Onset of Darcy-Brinkman Reaction-Convection in an Anisotropic Porous Layer
Directory of Open Access Journals (Sweden)
S. N. Gaikwad
2016-01-01
Full Text Available The linear and nonlinear stability analysis of double diffusive reaction-convection in a sparsely packed anisotropic porous layer subjected to chemical equilibrium on the boundaries is investigated analytically. The linear analysis is based on the usual normal mode method and the nonlinear theory on the truncated representation of Fourier series method. The Darcy-Brinkman model is employed for the momentum equation. The onset criterion for stationary, oscillatory and finite amplitude convection is derived analytically. The effect of Darcy number, Damkohler number, anisotropy parameters, Lewis number, and normalized porosity on the stationary, oscillatory, and finite amplitude convection is shown graphically. It is found that the effect of Darcy number and mechanical anisotropy parameter have destabilizing effect, while the thermal anisotropy parameter has stabilizing effect on the stationary, oscillatory and finite amplitude convection. The Damkohler number has destabilizing effect in the case of stationary mode, with stabilizing effect in the case of oscillatory and finite amplitude modes. Further, the transient behavior of the Nusselt and Sherwood numbers are investigated by solving the nonlinear system of ordinary differential equations numerically using the Runge-Kutta method.
Elastic Wave Propagation Simulation in Heterogeneous Anisotropic Media on Non-uniform Grids
Institute of Scientific and Technical Information of China (English)
孙卫涛; 杨慧珠
2004-01-01
A finite-difference method with spatially non-uniform grids was developed to simulate elastic wave propagation in heterogeneous anisotropic media. The method is very simple and requires less compution time. Complicated geometric structures, such as low-velocity layers, cased boreholes and nonplanar interfaces, are treated with fine non-uniform grids. Unlike the multi-grid scheme, this method does not require interpolation between the fine and coarse grids and all grids are computed in the same spatial iteration. Planar or nonplanar surfaces including underground lens and cased boreholes are easily treated in a way similar to regular grid points. The Higdon's absorbing boundary condition was used to eliminate boundary reflections. Numerical simulations show that the method has satisfactory stability and accuracy.The proposed scheme more efficiently simulates wave propagation in heterogeneous anisotropic media than conventional methods using regular rectangular grids of equal accuracy.
Influence of biofilms on transport properties in porous media
Davit, Y.
2015-12-01
Microbial activity and biofilm growth in porous media can drastically modify transport properties such as permeability, longitudinal and transverse dispersion or effective reaction rates. Understanding these effects has proven to be a considerable challenge. Advances in this field have been hindered by the difficulty of modeling and visualizing these multi-phase non-linear effects across a broad range of spatial and temporal scales. To address these issues, we are developing a strategy that combines imaging techniques based on x-ray micro-tomography with homogenization of pore-scale transport equations. Here, we review recent progress in x-ray imaging of biofilms in porous media, with a particular focus on the contrast agents that are used to differentiate between the fluid and biofilm phases. We further show how the 3D distribution of the different phases can be used to extract specific information about the biofilm and how effective properties can be calculated via the resolution of closure problems. These closure problems are obtained using the method of volume averaging and must be adapted to the problem of interest. In hydrological systems, we show that a generic formulation for reactive solute transport is based on a domain decomposition approach at the micro-scale yielding macro-scale models reminiscent of multi-rate mass transfer approaches.
A micropolar mixture theory of multi-component porous media
Institute of Scientific and Technical Information of China (English)
Lu HUANG; Cheng-gang ZHAO
2009-01-01
A mixture theory is developed for multi-component micropolar porous media with a combination of the hybrid mixture theory and the micropolar continuum theory.The system is modeled as multi-component micropolar elastic solids saturated with multicomponent micropolar viscous fluids. Balance equations are given through the mixture theory. Constitutive equations are developed based on the second law of thermodynamics and constitutive assumptions. Taking account of compressibility of solid phases,the volume fraction of fluid as an independent state variable is introduced in the free energy function,and the dynamic compatibility condition is obtained to restrict the change of pressure difference on the solid-fluid interface. The constructed constitutive equations are used to close the field equations. The linear field equations are obtained using a linearization procedure,and the micropolar thermo-hydro-mechanical component transport model is established. This model can be applied to practical problems,such as contaminant,drug,and pesticide transport. When the proposed model is supposed to be porous media,and both fluid and solid are single-component,it will almost agree with Eringen's model.
Studies on dispersive stabilization of porous media flows
Daripa, Prabir; Gin, Craig
2016-08-01
Motivated by a need to improve the performance of chemical enhanced oil recovery (EOR) processes, we investigate dispersive effects on the linear stability of three-layer porous media flow models of EOR for two different types of interfaces: permeable and impermeable interfaces. Results presented are relevant for the design of smarter interfaces in the available parameter space of capillary number, Peclet number, longitudinal and transverse dispersion, and the viscous profile of the middle layer. The stabilization capacity of each of these two interfaces is explored numerically and conditions for complete dispersive stabilization are identified for each of these two types of interfaces. Key results obtained are (i) three-layer porous media flows with permeable interfaces can be almost completely stabilized by diffusion if the optimal viscous profile is chosen, (ii) flows with impermeable interfaces can also be almost completely stabilized for short time, but become more unstable at later times because diffusion flattens out the basic viscous profile, (iii) diffusion stabilizes short waves more than long waves which leads to a "turning point" Peclet number at which short and long waves have the same growth rate, and (iv) mechanical dispersion further stabilizes flows with permeable interfaces but in some cases has a destabilizing effect for flows with impermeable interfaces, which is a surprising result. These results are then used to give a comparison of the two types of interfaces. It is found that for most values of the flow parameters, permeable interfaces suppress flow instability more than impermeable interfaces.
Multicomponent, multiphase flow in porous media with temperature variation
Energy Technology Data Exchange (ETDEWEB)
Wingard, J.S.; Orr, F.M. Jr.
1990-10-01
Recovery of hydrocarbons from porous media is an ongoing concern. Advanced techniques augment conventional recovery methods by injecting fluids that favorably interact with the oil. These fluids interact with the oil by energy transfer, in the case of steam injection, or by mass transfer, as in a miscible gas flood. Often both thermal and compositional considerations are important. An understanding of these injection methods requires knowledge of how temperature variations, phase equilibrium and multiphase flow in porous media interact. The material balance for each component and energy balance are cast as a system of non-strictly hyperbolic partial differential equations. This system of equations is solved using the method of characteristics. The model takes into account the phase behavior by using the Peng-Robinson equation of state to partition the individual components into different phases. Temperature effects are accounted for by the energy balance. Flow effects are modelled by using fractional flow curves and a Stone's three phase relative permeability model. Three problems are discussed. The first problem eliminates the phase behavior aspect of the problem by studying the flow of a single component as it undergoes an isothermal phase change. The second couples the effects of temperature and flow behavior by including a second component that is immiscible with the original component. Phase behavior is added by using a set of three partially miscible components that partition into two or three separate phases. 66 refs., 54 figs., 14 tabs.
Evaluation of liquid aerosol transport through porous media
Hall, R.; Murdoch, L.; Falta, R.; Looney, B.; Riha, B.
2016-07-01
Application of remediation methods in contaminated vadose zones has been hindered by an inability to effectively distribute liquid- or solid-phase amendments. Injection as aerosols in a carrier gas could be a viable method for achieving useful distributions of amendments in unsaturated materials. The objectives of this work were to characterize radial transport of aerosols in unsaturated porous media, and to develop capabilities for predicting results of aerosol injection scenarios at the field-scale. Transport processes were investigated by conducting lab-scale injection experiments with radial flow geometry, and predictive capabilities were obtained by developing and validating a numerical model for simulating coupled aerosol transport, deposition, and multi-phase flow in porous media. Soybean oil was transported more than 2 m through sand by injecting it as micron-scale aerosol droplets. Oil saturation in the sand increased with time to a maximum of 0.25, and decreased with radial distance in the experiments. The numerical analysis predicted the distribution of oil saturation with only minor calibration. The results indicated that evolution of oil saturation was controlled by aerosol deposition and subsequent flow of the liquid oil, and simulation requires including these two coupled processes. The calibrated model was used to evaluate field applications. The results suggest that amendments can be delivered to the vadose zone as aerosols, and that gas injection rate and aerosol particle size will be important controls on the process.
Electrokinetic induced solute dispersion in porous media; pore network modeling
Li, Shuai; Schotting, Ruud; Raoof, Amir
2013-04-01
Electrokinetic flow plays an important role in remediation process, separation technique, and chromatography. The solute dispersion is a key parameter to determine transport efficiency. In this study, we present the electrokinetic effects on solute dispersion in porous media at the pore scale, using a pore network model. The analytical solution of the electrokinetic coupling coefficient was obtained to quantity the fluid flow velocity in a cylinder capillary. The effect of electrical double layer on the electrokinetic coupling coefficient was investigated by applying different ionic concentration. By averaging the velocity over cross section within a single pore, the average flux was obtained. Applying such single pore relationships, in the thin electrical double layer limit, to each and every pore within the pore network, potential distribution and the induced fluid flow was calculated for the whole domain. The resulting pore velocities were used to simulate solute transport within the pore network. By averaging the results, we obtained the breakthrough curve (BTC) of the average concentration at the outlet of the pore network. Optimizing the solution of continuum scale advection-dispersion equation to such a BTC, solute dispersion coefficient was estimated. We have compared the dispersion caused by electrokinetic flow and pure pressure driven flow under different Peclet number values. In addition, the effect of microstructure and topological properties of porous media on fluid flow and solute dispersion is presented, mainly based on different pore coordination numbers.
Modeling of surfactant transport and adsorption in porous media
Energy Technology Data Exchange (ETDEWEB)
Chung, F.T.H.
1991-04-01
When surfactant solution is flowing in a reservoir formation, surfactants will be diluted by flow dispersion, retained in dead-end pores, adsorbed on rock surfaces, or precipitated due to ion exchange. The loss of surfactant will be detrimental to the performance of gas foam. Information of surfactant concentration profiles in reservoir formations is essential for gas foaming technique development. The major objective of this research is to investigate with mathematical models the transport and dynamic adsorption of surfactants in porous media. The mathematical models have taken into account the convection, dispersion, capacitance, and adsorption effects on concentrations of surfactants. Numerical methods and computer programs have been developed which can be used to match experimental results and to determine the characterization parameters in the models. The models can be included in foam simulation programs to calculate surfactant concentration profiles in porous media. A flow experimental method was developed to measure the effluent surfactant concentration, which will be used to determine the model parameters. Commercial foaming agent Alipal CD-128 was used in this study. Equilibrium adsorption and surfactant precipitation have been tested. Tracer solutions with a nonadsorbing solute such as dextrose and sucrose were used to determine the dispersion parameters for the experimental sandpack; thus, the adsorption of the surfactant in the test sand can be identified with an adequate model. 49 refs., 21 figs.
Geometric Models for Isotropic Random Porous Media: A Review
Directory of Open Access Journals (Sweden)
Helmut Hermann
2014-01-01
Full Text Available Models for random porous media are considered. The models are isotropic both from the local and the macroscopic point of view; that is, the pores have spherical shape or their surface shows piecewise spherical curvature, and there is no macroscopic gradient of any geometrical feature. Both closed-pore and open-pore systems are discussed. The Poisson grain model, the model of hard spheres packing, and the penetrable sphere model are used; variable size distribution of the pores is included. A parameter is introduced which controls the degree of open-porosity. Besides systems built up by a single solid phase, models for porous media with the internal surface coated by a second phase are treated. Volume fraction, surface area, and correlation functions are given explicitly where applicable; otherwise numerical methods for determination are described. Effective medium theory is applied to calculate physical properties for the models such as isotropic elastic moduli, thermal and electrical conductivity, and static dielectric constant. The methods presented are exemplified by applications: small-angle scattering of systems showing fractal-like behavior in limited ranges of linear dimension, optimization of nanoporous insulating materials, and improvement of properties of open-pore systems by atomic layer deposition of a second phase on the internal surface.
Experimentally Determined Interfacial Area Between Immiscible Fluids in Porous Media
Energy Technology Data Exchange (ETDEWEB)
Crandall, Dustin; Niessner, J; Hassanizadeh, S.M; Smith, Duane
2008-01-01
When multiple fluids flow through a porous medium, the interaction between the fluid interfaces can be of great importance. While this is widely recognized in practical applications, numerical models often disregard interactios between discrete fluid phases due to the computational complexity. And rightly so, for this level of detail is well beyond most extended Darcy Law relationships. A new model of two-phase flow including the interfacial area has been proposed by Hassarizadeh and Gray based upon thermodynamic principles. A version of this general equation set has been implemented by Nessner and Hassarizadeh. Many of the interfacial parameters required by this equation set have never been determined from experiments. The work presented here is a description of how the interfacial area, capillary pressure, interfacial velocity and interfacial permeability from two-phase flow experiments in porous media experiments can be used to determine the required parameters. This work, while on-going, has shown the possibility of digitizing images within translucent porous media and identifying the location and behavior of interfaces under dynamic conditions. Using the described methods experimentally derived interfacial functions to be used in larger scale simulations are currently being developed. In summary, the following conclusions can be drawn: (1) by mapping a pore-throat geometry onto an image of immiscible fluid flow, the saturation of fluids and the individual interfaces between the fluids can be identified; (2) the resulting saturation profiles of the low velocity drainage flows used in this study are well described by an invasion percolation fractal scaling; (3) the interfacial area between fluids has been observed to increase in a linear fashion during the initial invasion of the non-wetting fluid; and (4) the average capillary pressure within the entire cell and representative elemental volumes were observed to plateau after a small portion of the volume was
Modern hardware architectures accelerate porous media flow computations
Kulczewski, Michal; Kurowski, Krzysztof; Kierzynka, Michal; Dohnalik, Marek; Kaczmarczyk, Jan; Borujeni, Ali Takbiri
2012-05-01
Investigation of rock properties, porosity and permeability particularly, which determines transport media characteristic, is crucial to reservoir engineering. Nowadays, micro-tomography (micro-CT) methods allow to obtain vast of petro-physical properties. The micro-CT method facilitates visualization of pores structures and acquisition of total porosity factor, determined by sticking together 2D slices of scanned rock and applying proper absorption cut-off point. Proper segmentation of pores representation in 3D is important to solve the permeability of porous media. This factor is recently determined by the means of Computational Fluid Dynamics (CFD), a popular method to analyze problems related to fluid flows, taking advantage of numerical methods and constantly growing computing powers. The recent advent of novel multi-, many-core and graphics processing unit (GPU) hardware architectures allows scientists to benefit even more from parallel processing and built-in new features. The high level of parallel scalability offers both, the time-to-solution decrease and greater accuracy - top factors in reservoir engineering. This paper aims to present research results related to fluid flow simulations, particularly solving the total porosity and permeability of porous media, taking advantage of modern hardware architectures. In our approach total porosity is calculated by the means of general-purpose computing on multiple GPUs. This application sticks together 2D slices of scanned rock and by the means of a marching tetrahedra algorithm, creates a 3D representation of pores and calculates the total porosity. Experimental results are compared with data obtained via other popular methods, including Nuclear Magnetic Resonance (NMR), helium porosity and nitrogen permeability tests. Then CFD simulations are performed on a large-scale high performance hardware architecture to solve the flow and permeability of porous media. In our experiments we used Lattice Boltzmann
A multipoint flux approximation of the steady-state heat conduction equation in anisotropic media
Salama, Amgad
2013-03-20
In this work, we introduce multipoint flux (MF) approximation method to the problem of conduction heat transfer in anisotropic media. In such media, the heat flux vector is no longer coincident with the temperature gradient vector. In this case, thermal conductivity is described as a second order tensor that usually requires, at least, six quantities to be fully defined in general three-dimensional problems. The two-point flux finite differences approximation may not handle such anisotropy and essentially more points need to be involved to describe the heat flux vector. In the framework of mixed finite element method (MFE), the MFMFE methods are locally conservative with continuous normal fluxes. We consider the lowest order Brezzi-Douglas-Marini (BDM) mixed finite element method with a special quadrature rule that allows for nodal velocity elimination resulting in a cell-centered system for the temperature. We show comparisons with some analytical solution of the problem of conduction heat transfer in anisotropic long strip. We also consider the problem of heat conduction in a bounded, rectangular domain with different anisotropy scenarios. It is noticed that the temperature field is significantly affected by such anisotropy scenarios. Also, the technique used in this work has shown that it is possible to use the finite difference settings to handle heat transfer in anisotropic media. In this case, heat flux vectors, for the case of rectangular mesh, generally require six points to be described. Copyright © 2013 by ASME.
Tan, Eng Leong
2005-12-01
This paper presents the recursive algorithm of stiffness matrix method with improved efficiency for computing the total and surface stiffness matrices for a general multilayered anisotropic media. Based on the eigensolutions commonly available for analysis of such media, the recursive algorithm deals with eigen-submatrices directly and bypasses all intermediate layer stiffness submatrices. The improved algorithm obviates the need to compute certain inverse of the original scheme and makes the stiffness matrix recursion more robust. In situation where transfer matrix is numerically stable and easily accessible, an improved recursive algorithm is also given directly in terms of transfer submatrices without involving their explicit inverse.
Review of key factors controlling engineered nanoparticle transport in porous media.
Wang, Mei; Gao, Bin; Tang, Deshan
2016-11-15
Nanotechnology, an emerging technology, has witnessed rapid development in production and application. Engineered nanomaterials revolutionize the industry due to their unique structure and superior performance. The release of engineered nanoparticles (ENPs) into the environment, however, may pose risks to the environment and public health. To advance current understanding of environmental behaviors of ENPs, this work provides an introductory overview of ENP fate and transport in porous media. It systematically reviews the key factors controlling their fate and transport in porous media. It first provides a brief overview of common ENPs in the environment and their sources. The key factors that govern ENP transport in porous media are then categorized into three groups: (1) nature of ENPs affecting their transport in porous media, (2) nature of porous media affecting ENP transport, and (3) nature of flow affecting ENP transport in porous media. In each group, findings in recent literature on the specific governing factors of ENP transport in porous media are discussed in details. Finally, this work concludes with remarks on the importance of ENP transport in porous media and directions for future research. PMID:27427890
Analysis for the Potential Function of the Digital Microstructure Image of Porous Media
Institute of Scientific and Technical Information of China (English)
XU You-Sheng; LIN Ji; LI Hua-Mei; WU Feng-Min
2003-01-01
Making use of the full information obtained in our previous discussions, a new analytical solutions for thepotential function of the digital microstructure image of porous media is reported in this paper. It is demonstrated that the distribution of potential function depends on the zeroth order Bessel function. All these will be helpful for analyzingthe similar subjects in porous media.
Analysis for the Potential Function of the Digital Microstructure Image of Porous Media
Institute of Scientific and Technical Information of China (English)
XUYou-Sheng; LINJi; LIHua-Mei; WUPeng-Min
2003-01-01
Making use of the full information obtained in our previous discussions, a new analytical solutions for the potential function of the digital microstructure image of porous media is reported in this paper. It is demonstrated that the distribution of potential function depends on the zeroth order Bessel function. All these will be helpful for analyzing the similar subjects in porous media.
A New Capacitance Probe for Measuring the Local Moisture Content in Wet Porous Media
Institute of Scientific and Technical Information of China (English)
HanJitian; ShiMingheng; 等
1997-01-01
A new capacitance probe is developed for measuring local moisture content in wet porous media.The measurement principle,sensor structure of the probe,dynamic response characteristics and calibration procedure are discussed in detail.The experimental results show that the probe can be used to measure the local moisture content in wet porous media.
A New Appraoch to Modeling Immiscible Two-phase Flow in Porous Media
DEFF Research Database (Denmark)
Yuan, Hao; Shapiro, Alexander; Stenby, Erling Halfdan
to modeling immiscible two-phase flow in porous media. The suggested approach to immiscible two-phase flow in porous media describes the dispersed mesoscopic fluids’ interfaces which are highly influenced by the injected interfacial energy and the local interfacial energy capacity. It reveals a new...
Gao, Kai
2015-06-05
The development of reliable methods for upscaling fine-scale models of elastic media has long been an important topic for rock physics and applied seismology. Several effective medium theories have been developed to provide elastic parameters for materials such as finely layered media or randomly oriented or aligned fractures. In such cases, the analytic solutions for upscaled properties can be used for accurate prediction of wave propagation. However, such theories cannot be applied directly to homogenize elastic media with more complex, arbitrary spatial heterogeneity. Therefore, we have proposed a numerical homogenization algorithm based on multiscale finite-element methods for simulating elastic wave propagation in heterogeneous, anisotropic elastic media. Specifically, our method used multiscale basis functions obtained from a local linear elasticity problem with appropriately defined boundary conditions. Homogenized, effective medium parameters were then computed using these basis functions, and the approach applied a numerical discretization that was similar to the rotated staggered-grid finite-difference scheme. Comparisons of the results from our method and from conventional, analytical approaches for finely layered media showed that the homogenization reliably estimated elastic parameters for this simple geometry. Additional tests examined anisotropic models with arbitrary spatial heterogeneity in which the average size of the heterogeneities ranged from several centimeters to several meters, and the ratio between the dominant wavelength and the average size of the arbitrary heterogeneities ranged from 10 to 100. Comparisons to finite-difference simulations proved that the numerical homogenization was equally accurate for these complex cases.
Fluid structure interaction for fluid flow normal to deformable porous media
Muntz, Sabine
2008-01-01
In this thesis, the coupling of the Stokes equations and the Biot poroelasticity equations for fluid flow normal to porous media is investigated. For that purpose, the transmission conditions across the interfaces between the fluid regions and the porous domain are derived. A proper algorithm is formulated and numerical examples are presented. First, the transmission conditions for the coupling of various physical phenomena are reviewed. For the coupling of free flow with porous media, it has...
Fractal Analysis of Robertson-Stiff Fluid Flow in Porous Media
International Nuclear Information System (INIS)
The Robertson—Stiff (RS) fluid is the representative fluid which may be reduced to Bingham, power-law and Newtonian fluids under appropriate conditions. We present fractal models for the flow rate, velocity, starting pressure gradient and effective permeability for RS fluids in porous media based on the fractal characteristics of porous media and capillary models. The proposed models are expressed as functions of the fractal dimensions, porosity, maximum pore size and the representative length of the porous media. Every parameter in the proposed expressions has clear physical meaning, and the proposed models relate the flow characteristics of the RS fluids to the structural parameters of the porous media. The analytical expressions reveal the physical principles of RS fluid flow in porous media. (fundamental areas of phenomenology(including applications))
Modelling of transport processes in porous media for energy applications
Energy Technology Data Exchange (ETDEWEB)
Kangas, M.
1996-12-31
Flows in porous media are encountered in many branches of technology. In these phenomena, a fluid of some sort is flowing through porous matrix of a solid medium. Examples of the fluid are water, air, gas and oil. The solid matrix can be soil, fissured rock, ceramics, filter paper, etc. The flow is in many cases accompanied by transfer of heat or solute within the fluid or between the fluid and the surrounding solid matrix. Chemical reactions or microbiological processes may also be taking place in the system. In this thesis, a 3-dimensional computer simulation model THETA for the coupled transport of fluid, heat, and solute in porous media has been developed and applied to various problems in the field of energy research. Although also applicable to porous medium applications in general, the version of the model described and used in this work is intended for studying the transport processes in aquifers, which are geological formations containing groundwater. The model highlights include versatile input and output routines, as well as modularity which, for example, enables an easy adaptation of the model for use as a subroutine in large energy system simulations. Special attention in the model development has been attached to high flow conditions, which may be present in Nordic esker aquifers located close to the ground surface. The simulation model has been written with FORTRAN 77 programming language, enabling a seamless operation both in PC and main frame environments. For PC simulation, a special graphic user interface has been developed. The model has been used with success in a wide variety of applications, ranging from basic thermal analyses to thermal energy storage system evaluations and nuclear waste disposal simulations. The studies have shown that thermal energy storage is feasible also in Nordic high flow aquifers, although at the cost of lower recovery temperature level, usually necessitating the use of heat pumps. In the nuclear waste studies, it
Microbial growth and transport in saturated and unsaturated porous media
Hron, Pavel; Jost, Daniel; Bastian, Peter; Ippisch, Olaf
2014-05-01
There is a considerable ongoing effort aimed at understanding the behavior of microorganisms in porous media. Microbial activity is of significant interest in various environmental applications such as in situ bioremediation, protection of drinking water supplies and for subsurface geochemistry in general. The main limiting factors for bacterial growth are the availability of electron acceptors, nutrients and bio-available water. The capillary fringe, defined - in a wider sense than usual - as the region of the subsurface above the groundwater table, but still dominated by capillary rise, is a region where all these factors are abundantly available. It is thus a region where high microbial activity is to be expected. In a research unit 'Dynamic Capillary Fringes - A Multidisciplinary Approach (DyCap)' founded by the German Research Foundation (DFG), the growth of microorganisms in the capillary fringe was studied experimentally and with numerical simulations. Processes like component transport and diffusion, exchange between the liquid phase and the gas phase, microbial growth and cell attachment and detachment were incorporated into a numerical simulator. The growth of the facultative anaerobic Escherichia coli as a function of nutrient availability and oxygen concentration in the liquid phase is modeled with modified Monod-type models and modifications for the switch between aerobic and anaerobic growth. Laboratory batch experiments with aqueous solutions of bacteria have been carried out under various combinations of oxygen concentrations in the gas phase and added amounts of dissolved organic carbon to determine the growth model parameters by solution of a parameter estimation problem. For the transport of bacteria the adhesion to phase boundaries is also very important. As microorganisms are transported through porous media, they are removed from the pore fluid by physicochemical filtration (attachment to sediment grain surfaces) or are adhering to gas
Mobility of engineered inorganic nanoparticles in porous media
Metreveli, George; Heidmann, Ilona; Schaumann, Gabriele Ellen
2013-04-01
Besides the excellent properties and great potential for various industrial, medical, pharmaceutical, cosmetic, and life science applications, engineered inorganic nanoparticles (EINP) can show also disadvantages concerning increasing risk potential with increasing application, if they are released in the environmental systems. EINP can influence microbial activity and can show toxic effects (Fabrega et al., 2009). Similar to the inorganic natural colloids, EINP can be transported in soil and groundwater systems (Metreveli et al., 2005). Furthermore, due to the large surface area and high sorption and complex formation capacity, EINP can facilitate transport of different contaminants. In this study the mobility behaviour of EINP and their effect on the transport of different metal(loid) species in water saturated porous media was investigated. For these experiments laboratory column system was used. The column was filled with quartz sand. The interactions between EINP and metal(loid)s were characterised by coupling of asymmetrical flow field flow fractionation (AF4) with inductively coupled plasma mass spectrometer (ICP-MS). As EINP laponite (synthetic three layer clay mineral), and as metal(loid)s Cu, Pb, Zn, Pt and As were used. In AF4 experiments sorption of metal(loid)s on the surface of EINP could be observed. The extent of interactions was influenced by pH value and was different for different metal(loid)s. Laboratory column experiments showed high mobility of EINP, which facilitated transport of most of metal(loid)s in water saturated porous media. Furthermore the migration of synthetic silver nanoparticles in natural soil columns was determined in leaching experiments. Acknowledgement Financial support by German Research Council (DFG) and Max-Buchner-Research Foundation (MBFSt) is gratefully acknowledged. We thank Karlsruhe Institute of Technology (KIT) for the opportunity to perform the column and AF4 experiments. References: Fabrega, J., Fawcett, S. R
Transport of molecular fluids through three-dimensional porous media
Adler, Pierre; Pazdniakou, Aliaksei
2014-05-01
The main purpose of this study is to extend the analysis which has been made for the double layer theory (summarized by [1]) to situations where the distance between the solid walls is of the order of several molecular diameters. This is of a large interest from a scientific viewpoint and for various engineering applications. The intermolecular forces and their influence on fluid structure and dynamics can be taken into account by using the mesoscopic scale models based on the Boltzmann equation [2]. The numerical methods derived from these models are less demanding in computational resources than conventional molecular dynamics methods and therefore long time evolution of large samples can be considered. Three types of fluid particles are considered, namely the anions, the cations and the solvent. They possess a finite diameter which should be at least a few lattice units. The collision frequency between particles is increased by the pair correlation function for hard spheres. The lattice Boltzmann model is built in three dimensions with 19 velocities; it involves two relaxation times. The particle distribution functions are discretized over a basis of Hermite polynomial tensors. Electric forces are included and a Poisson equation is simultaneously solved by a successive over-relaxation method. The numerical algorithm is detailed; it is devised in order to be able to address any three-dimensional porous media. It involves the determination of the densities of each particle species, of the overall density and of the equilibrium distribution function. Then, the electric forces are determined. Collision operators are applied as well as the boundary conditions. Finally, the propagation step is performed and the algorithm starts a new loop. The influence of parameters can be illustrated by systematic calculations in a plane Poiseuille configuration. The drastic influence of the ratio between the channel width and the particle sizes on the local densities and the
Wave propagation in solid and porous half-space media
Hamidzadeh, Hamid R; Jazar, Reza N
2014-01-01
This unique book covers advanced topics in dynamic modeling of soil-foundation interaction, as well as the response of elastic semi-infinite media from an applications viewpoint. Advanced concepts such as solutions for analysis of elastic semi-infinite mediums, fluid motion in porous media, and nonlinearities in dynamic behavior are explained in great detail. Related theories and numerical analysis for independent vertical, horizontal, and rocking as well as coupled horizontal and rocking vibrations of a rigid rectangular base resting on the surface of a semi-infinite medium are presented. Throughout the book, a strong emphasis is placed on applications. A laboratory model for elastic half-space medium is also described. This book also: · Provides a systematic solution for analysis of elastic semi-infinite mediums when subjected to different loading conditions · Offers a solution for the continuous elastic medium that is also extended to visco-elastic media by considering com...
Phase field modeling of partially saturated deformable porous media
Sciarra, Giulio
2016-09-01
A poromechanical model of partially saturated deformable porous media is proposed based on a phase field approach at modeling the behavior of the mixture of liquid water and wet air, which saturates the pore space, the phase field being the saturation (ratio). While the standard retention curve is expected still^ to provide the intrinsic retention properties of the porous skeleton, depending on the porous texture, an enhanced description of surface tension between the wetting (liquid water) and the non-wetting (wet air) fluid, occupying the pore space, is stated considering a regularization of the phase field model based on an additional contribution to the overall free energy depending on the saturation gradient. The aim is to provide a more refined description of surface tension interactions. An enhanced constitutive relation for the capillary pressure is established together with a suitable generalization of Darcy's law, in which the gradient of the capillary pressure is replaced by the gradient of the so-called generalized chemical potential, which also accounts for the "force", associated to the local free energy of the phase field model. A micro-scale heuristic interpretation of the novel constitutive law of capillary pressure is proposed, in order to compare the envisaged model with that one endowed with the concept of average interfacial area. The considered poromechanical model is formulated within the framework of strain gradient theory in order to account for possible effects, at laboratory scale, of the micro-scale hydro-mechanical couplings between highly localized flows (fingering) and localized deformations of the skeleton (fracturing).
Sanchez-Valencia, Juan Ramon; Longtin, Remi; Rossell, Marta D; Gröning, Pierangelo
2016-04-01
We report a new methodology based on glancing angle deposition (GLAD) of an organic molecule in combination with perpendicular growth of a second inorganic material. The resulting thin films retain a very well-defined tilted columnar microstructure characteristic of GLAD with the inorganic material embedded inside the columns. We refer to this new methodology as growth assisted by glancing angle deposition or GAGLAD, since the material of interest (here, the inorganic) grows in the form of tilted columns, though it is deposited under a nonglancing configuration. As a "proof of concept", we have used silver and zinc oxide as the perpendicularly deposited material since they usually form ill-defined columnar microstructures at room temperature by GLAD. By means of our GAGLAD methodology, the typical tilted columnar microstructure can be developed for materials that otherwise do not form ordered structures under conventional GLAD. This simple methodology broadens significantly the range of materials where control of the microstructure can be achieved by tuning the geometrical deposition parameters. The two examples presented here, Ag/Alq3 and ZnO/Alq3, have been deposited by physical vapor deposition (PVD) and plasma enhanced chemical vapor deposition (PECVD), respectively: two different vacuum techniques that illustrate the generality of the proposed technique. The two type of hybrid samples present very interesting properties that demonstrate the potentiality of GAGLAD. On one hand, the Ag/Alq3 samples present highly optical anisotropic properties when they are analyzed with linearly polarized light. To our knowledge, these Ag/Alq3 samples present the highest angular selectivity reported in the visible range. On the other hand, ZnO/Alq3 samples are used to develop highly porous ZnO thin films by using Alq3 as sacrificial material. In this way, antireflective ZnO samples with very low refractive index and extinction coefficient have been obtained. PMID:26954074
Roth, E. J.; Tigera, R. G.; Crimaldi, J. P.; Mays, D. C.
2015-12-01
Research in porous media is often hampered by the difficulty in making pore-scale observations. By selecting porous media that is refractive index matched (RIM) to the pore fluid, the media becomes transparent. This allows optical imaging techniques such as static light scattering (SLS), dynamic light scattering (DLS), confocal microscopy, and planar laser-induced fluorescence (PLIF) to be employed. RIM is particularly useful for research concerning contaminant remediation in the subsurface, permitting visual observation of plume dynamics at the pore scale. The goal of this research is to explore and assess candidate combinations of porous media, fluid, and fluorescent dye. The strengths and weaknesses of each combination will then be evaluated in terms of safety, cost, and optical quality in order to select the best combination for use with PLIF. Within this framework, top-ranked RIM combinations include Pyrex glass beads, water beads, or granular Nafion saturated in vegetable glycerin, deionized water, and an aqueous solution of 48% isopropanol, respectively. This research lays the groundwork for future efforts to build a flow chamber in which the selected RIM porous media, solution, and dye will be used in evaluating subsurface pumping strategies designed to impose chaotic plume spreading in porous media. Though the RIM porous media explored in this research are selected based on the specifications of a particular experiment, the methods developed for working with and evaluating RIM porous media should be of utility to a wide variety of research interests.
Efficient algorithms for multiscale modeling in porous media
Wheeler, Mary F.
2010-09-26
We describe multiscale mortar mixed finite element discretizations for second-order elliptic and nonlinear parabolic equations modeling Darcy flow in porous media. The continuity of flux is imposed via a mortar finite element space on a coarse grid scale, while the equations in the coarse elements (or subdomains) are discretized on a fine grid scale. We discuss the construction of multiscale mortar basis and extend this concept to nonlinear interface operators. We present a multiscale preconditioning strategy to minimize the computational cost associated with construction of the multiscale mortar basis. We also discuss the use of appropriate quadrature rules and approximation spaces to reduce the saddle point system to a cell-centered pressure scheme. In particular, we focus on multiscale mortar multipoint flux approximation method for general hexahedral grids and full tensor permeabilities. Numerical results are presented to verify the accuracy and efficiency of these approaches. © 2010 John Wiley & Sons, Ltd.
Biopolymer system for permeability modification in porous media
Energy Technology Data Exchange (ETDEWEB)
Stepp, A.K.; Bryant, R.S.; Llave, F.M. [BMD-Oklahoma, Inc., Bartlesville, OK (United States)] [and others
1995-12-31
New technologies are needed to reduce the current high rate of well abandonment. Improved sweep efficiency, reservoir conformance, and permeability modification can have a significant impact on oil recovery processes. Microorganisms can be used to selectively plug high-permeability zones to improve sweep efficiency and impart conformance control. Studies of a promising microbial system for polymer production were conducted to evaluate reservoir conditions in which this system would be effective. Factors which can affect microbial growth and polymer production include salinity, pH, temperature, divalent ions, presence of residual oil, and rock matrix. Flask tests and coreflooding experiments were conducted to optimize and evaluate the effectiveness of this system. Nuclear magnetic resonance imaging (NMRI) was used to visualize microbial polymer production in porous media. Changes in fluid distribution within the pore system of the core were detected.
Strength and stability of microbial plugs in porous media
Energy Technology Data Exchange (ETDEWEB)
Sarkar, A.K. [NIPER/BDM-Oklahoma, Inc., Bartlesville, OK (United States); Sharma, M.M.; Georgiou, G. [Univ. of Texas, Austin, TX (United States)
1995-12-31
Mobility reduction induced by the growth and metabolism of bacteria in high-permeability layers of heterogeneous reservoirs is an economically attractive technique to improve sweep efficiency. This paper describes an experimental study conducted in sandpacks using an injected bacterium to investigate the strength and stability of microbial plugs in porous media. Successful convective transport of bacteria is important for achieving sufficient initial bacteria distribution. The chemotactic and diffusive fluxes are probably not significant even under static conditions. Mobility reduction depends upon the initial cell concentrations and increase in cell mass. For single or multiple static or dynamic growth techniques, permeability reduction was approximately 70% of the original permeability. The stability of these microbial plugs to increases in pressure gradient and changes in cell physiology in a nutrient-depleted environment needs to be improved.
On the transport of emulsions in porous media
Energy Technology Data Exchange (ETDEWEB)
Cortis, Andrea; Ghezzehei, Teamrat A.
2007-06-27
Emulsions appear in many subsurface applications includingbioremediation, surfactant-enhanced remediation, and enhancedoil-recovery. Modeling emulsion transport in porous media is particularlychallenging because the rheological and physical properties of emulsionsare different from averages of the components. Current modelingapproaches are based on filtration theories, which are not suited toadequately address the pore-scale permeability fluctuations and reductionof absolute permeability that are often encountered during emulsiontransport. In this communication, we introduce a continuous time randomwalk based alternative approach that captures these unique features ofemulsion transport. Calculations based on the proposed approach resultedin excellent match with experimental observations of emulsionbreakthrough from the literature. Specifically, the new approach explainsthe slow late-time tailing behavior that could not be fitted using thestandard approach. The theory presented in this paper also provides animportant stepping stone toward a generalizedself-consistent modeling ofmultiphase flow.
Environmental behavior of engineered nanomaterials in porous media: a review.
Park, Chang Min; Chu, Kyoung Hoon; Heo, Jiyong; Her, Namguk; Jang, Min; Son, Ahjeong; Yoon, Yeomin
2016-05-15
A pronounced increase in the use of nanotechnology has resulted in nanomaterials being released into the environment. Environmental exposure to the most common engineered nanomaterials (ENMs), such as carbon-based and metal-based nanomaterials, can occur directly via intentional injection for remediation purposes, release during the use of nanomaterial-containing consumer goods, or indirectly via different routes. Recent reviews have outlined potential risks assessments, toxicity, and life cycle analyses regarding ENM emission. In this review, inevitable release of ENMs and their environmental behaviors in aqueous porous media are discussed with an emphasis on influencing factors, including the physicochemical properties of ENMs, solution chemistry, soil hydraulic properties, and soil matrices. Major findings of laboratory column studies and numerical approaches for the transport of ENMs are addressed, and studies on the interaction between ENMs and heavy metal ions in aqueous soil environments are examined. Future research is also presented with specific research directions and outlooks. PMID:26882524
Effect of Boundary Conditions on Freezing in Porous Media
Directory of Open Access Journals (Sweden)
Rahul Basu
2004-07-01
Full Text Available This paper examines a model for coupled heat and mass transfer for freezing in a porous media with Dirichlet and convective boundary conditions. Variables include porosity, heat transfer coefficients, thermal and mass diffusivity, density, latent heat, and boundary temperatures. A simulation for the slab illustrates the appearance of undercooling. A stability criterion for the phase interface is linked with well-known metallurgical parameters like undercooling and freezing rate. A possible mechanism for freckling in ingots of niobium-rich superalloys is examined. It has been shown that heat and mass transfer balance at the interface can affect stability. The effect of boundary conditions on the velocity of freezing is computed for some cases, including the self-freezing process.
Gelfand-type problem for two-phase porous media.
Gordon, Peter V; Moroz, Vitaly
2014-03-01
We consider a generalization of the Gelfand problem arising in Frank-Kamenetskii theory of thermal explosion. This generalization is a natural extension of the Gelfand problem to two-phase materials, where, in contrast to the classical Gelfand problem which uses a single temperature approach, the state of the system is described by two different temperatures. We show that similar to the classical Gelfand problem the thermal explosion occurs exclusively owing to the absence of stationary temperature distribution. We also show that the presence of interphase heat exchange delays a thermal explosion. Moreover, we prove that in the limit of infinite heat exchange between phases the problem of thermal explosion in two-phase porous media reduces to the classical Gelfand problem with renormalized constants.
Simulation of a Heat Transfer in Porous Media
Geiser, Juergen
2012-01-01
We are motivated to model a heat transfer to a multiple layer regime and their optimization for heat energy resources. Such a problem can be modeled by a porous media with different phases (liquid and solid). The idea arose of a geothermal energy reservoir which can be used by cities, e.g. Berlin. While hot ground areas are covered to most high populated cites, the energy resources are important and a shift to use such resources are enormous. We design a model of the heat transport via the flow of water through the heterogeneous layer of the underlying earth sediments. We discuss a multiple layer model, based on mobile and immobile zones. Such numerical simulations help to economize on expensive physical experiments and obtain control mechanisms for the delicate heating process.
Review of permeability evolution model for fractured porous media
Institute of Scientific and Technical Information of China (English)
Jianjun Ma
2015-01-01
The ability to capture permeability of fractured porous media plays a significant role in several engi-neering applications, including reservoir, mining, petroleum and geotechnical engineering. In order to solve fluid flow and coupled flow-deformation problems encountered in these engineering applications, both empirical and theoretical models had been proposed in the past few decades. Some of them are simple but still work in certain circumstances;others are complex but also need some modifications to be applicable. Thus, the understanding of state-of-the-art permeability evolution model would help researchers and engineers solve engineering problems through an appropriate approach. This paper summarizes permeability evolution models proposed by earlier and recent researchers with emphasis on their characteristics and limitations.
Centrifuge Techniques and Apparatus for Transport Experiments in Porous Media
Energy Technology Data Exchange (ETDEWEB)
Earl D. Mattson; Carl D. Paler; Robert W. Smith; Markus Flury
2010-06-01
This paper describes experimental approaches and apparatus that we have developed to study solute and colloid transport in porous media using Idaho National Laboratory's 2-m radius centrifuge. The ex-perimental techniques include water flux scaling with applied acceleration at the top of the column and sub-atmospheric pressure control at the column base, automation of data collection, and remote experimental con-trol over the internet. These apparatus include a constant displacement piston pump, a custom designed liquid fraction collector based on switching valve technology, and modified moisture monitoring equipment. Suc-cessful development of these experimental techniques and equipment is illustrated through application to transport of a conservative tracer through unsaturated sand column, with centrifugal acceleration up to 40 gs. Development of such experimental equipment that can withstand high accelerations enhances the centrifuge technique to conduct highly controlled unsaturated solute/colloid transport experiments and allows in-flight liquid sample collection of the effluent.
Evaluation of QNI corrections in porous media applications
Radebe, M. J.; de Beer, F. C.; Nshimirimana, R.
2011-09-01
Qualitative measurements using digital neutron imaging has been the more explored aspect than accurate quantitative measurements. The reason for this bias is that quantitative measurements require correction for background and material scatter, and neutron spectral effects. Quantitative Neutron Imaging (QNI) software package has resulted from efforts at the Paul Scherrer Institute, Helmholtz Zentrum Berlin (HZB) and Necsa to correct for these effects, while the sample-detector distance (SDD) principle has previously been demonstrated as a measure to eliminate material scatter effect. This work evaluates the capabilities of the QNI software package to produce accurate quantitative results on specific characteristics of porous media, and its role to nondestructive quantification of material with and without calibration. The work further complements QNI abilities by the use of different SDDs. Studies of effective %porosity of mortar and attenuation coefficient of water using QNI and SDD principle are reported.
Alaoui-Ismaili, N.; Guy, P.; Chassignole, B.
2014-02-01
The aim of this work is to measure the complex elastic tensor and Euler angles in very complex anisotropic media like austenitic steel welds, by inverse problem resolution from experimental data. The obtained experimental characteristics of the anisotropic material will be injected in a FE code developed by EDF enabling the simulation of an actual ultrasonic NDE of welds. The present work aims to provide reliable input data to the 3D future development of the code. In particular, this complex elastic tensor will allow to predict by modeling beam skewing ant attenuation in an austenitic weld. The investigation of such anisotropic media is very complex because of the directional dependency of the elastic stiffness tensor. Then we will discuss the use of a hybrid genetic algorithm to overcome this difficulty. The identification method is based on waveforms spectra reconstruction associated to a physical model describing wave propagation in plates, during underwater measurements. The entire procedure is qualified and validated using simulated data. Moreover, a comparison of the estimated elastic coefficients with literature values and ultrasonic measurements obtained in transmission is also given, at the end of the paper.
Energy Technology Data Exchange (ETDEWEB)
Alaoui-Ismaili, N. [INSA-Lyon, MATEIS, UMR5510 Villeurbanne, F-69621 (France); Guy, P. [INSA-Lyon, LVA, EA677 Villeurbanne, F-69621 (France); Chassignole, B. [EDF R and D, Moret sur Loing, F77818 (France)
2014-02-18
The aim of this work is to measure the complex elastic tensor and Euler angles in very complex anisotropic media like austenitic steel welds, by inverse problem resolution from experimental data. The obtained experimental characteristics of the anisotropic material will be injected in a FE code developed by EDF enabling the simulation of an actual ultrasonic NDE of welds. The present work aims to provide reliable input data to the 3D future development of the code. In particular, this complex elastic tensor will allow to predict by modeling beam skewing ant attenuation in an austenitic weld. The investigation of such anisotropic media is very complex because of the directional dependency of the elastic stiffness tensor. Then we will discuss the use of a hybrid genetic algorithm to overcome this difficulty. The identification method is based on waveforms spectra reconstruction associated to a physical model describing wave propagation in plates, during underwater measurements. The entire procedure is qualified and validated using simulated data. Moreover, a comparison of the estimated elastic coefficients with literature values and ultrasonic measurements obtained in transmission is also given, at the end of the paper.
Overlimiting Current and Shock Electrodialysis in Porous Media
Deng, Daosheng; Han, Ji-Hyung; Schlumpberger, Sven; Mani, Ali; Zaltzman, Boris; Bazant, Martin Z
2013-01-01
Most electrochemical processes, such as electrodialysis, are limited by diffusion, but in porous media, surface conduction and electro-osmotic flow also contribute to ionic fluxes. In this paper, we report experimental evidence for surface-driven over-limiting current (faster than diffusion) and deionization shocks (propagating salt removal) in a porous medium. The apparatus consists of a silica glass frit (1 mm thick with 500 nm mean pore size) in an aqueous electrolyte (CuSO$_4$ or AgNO$_3$) passing ionic current from a reservoir to a cation-selective membrane (Nafion). The current-voltage relation of the whole system is consistent with a proposed theory based on the electro-osmotic flow mechanism over a broad range of reservoir salt concentrations (0.1 mM - 1.0 M), after accounting for (Cu) electrode polarization and pH-regulated silica charge. Above the limiting current, deionized water ($\\approx 10 \\mu$ $M$) can be continuously extracted from the frit, which implies the existence of a stable shock propag...
Scaling heat and mass flow through porous media during pyrolysis
Maes, Julien; Muggeridge, Ann H.; Jackson, Matthew D.; Quintard, Michel; Lapene, Alexandre
2015-03-01
The modelling of heat and mass flow through porous media in the presence of pyrolysis is complex because various physical and chemical phenomena need to be represented. In addition to the transport of heat by conduction and convection, and the change of properties with varying pressure and temperature, these processes involve transport of mass by convection, evaporation, condensation and pyrolysis chemical reactions. Examples of such processes include pyrolysis of wood, thermal decomposition of polymer composite and in situ upgrading of heavy oil and oil shale. The behaviours of these systems are difficult to predict as relatively small changes in the material composition can significantly change the thermophysical properties. Scaling reduces the number of parameters in the problem statement and quantifies the relative importance of the various dimensional parameters such as permeability, thermal conduction and reaction constants. This paper uses inspectional analysis to determine the minimum number of dimensionless scaling groups that describe the decomposition of a solid porous material into a gas in one dimension. Experimental design is then used to rank these scaling groups in terms of their importance in describing the outcome of two example processes: the thermal decomposition of heat shields formed from polymer composites and the in situ upgrading of heavy oils and oil shales. A sensitivity analysis is used to divide these groups into three sets (primary, secondary and insignificant), thus identifying the combinations of solid and fluid properties that have the most impact on the performance of the different processes.
Overlimiting current and shock electrodialysis in porous media.
Deng, Daosheng; Dydek, E Victoria; Han, Ji-Hyung; Schlumpberger, Sven; Mani, Ali; Zaltzman, Boris; Bazant, Martin Z
2013-12-31
Most electrochemical processes, such as electrodialysis, are limited by diffusion, but in porous media, surface conduction and electroosmotic flow also contribute to ionic flux. In this article, we report experimental evidence for surface-driven overlimiting current (faster than diffusion) and deionization shocks (propagating salt removal) in a porous medium. The apparatus consists of a silica glass frit (1 mm thick with a 500 nm mean pore size) in an aqueous electrolyte (CuSO4 or AgNO3) passing ionic current from a reservoir to a cation-selective membrane (Nafion). The current-voltage relation of the whole system is consistent with a proposed theory based on the electroosmotic flow mechanism over a broad range of reservoir salt concentrations (0.1 mM to 1.0 M) after accounting for (Cu) electrode polarization and pH-regulated silica charge. Above the limiting current, deionized water (≈10 μM) can be continuously extracted from the frit, which implies the existence of a stable shock propagating against the flow, bordering a depleted region that extends more than 0.5 mm across the outlet. The results suggest the feasibility of shock electrodialysis as a new approach to water desalination and other electrochemical separations. PMID:24320737
A Monte Carlo paradigm for capillarity in porous media
Lu, Ning; Zeidman, Benjamin D.; Lusk, Mark T.; Willson, Clinton S.; Wu, David T.
2010-12-01
Wet porous media are ubiquitous in nature as soils, rocks, plants, and bones, and in engineering settings such as oil production, ground stability, filtration and composites. Their physical and chemical behavior is governed by the distribution of liquid and interfaces between phases. Characterization of the interfacial distribution is mostly based on macroscopic experiments, aided by empirical formulae. We present an alternative computational paradigm utilizing a Monte Carlo algorithm to simulate interfaces in complex realistic pore geometries. The method agrees with analytical solutions available only for idealized pore geometries, and is in quantitative agreement with Micro X-ray Computed Tomography (microXCT), capillary pressure, and interfacial area measurements for natural soils. We demonstrate that this methodology predicts macroscopic properties such as the capillary pressure and air-liquid interface area versus liquid saturation based only on the pore size information from microXCT images and interfacial interaction energies. The generality of this method should allow simulation of capillarity in many porous materials.
A Monte Carlo paradigm for capillarity in porous media
Energy Technology Data Exchange (ETDEWEB)
Lu, Ning; Zeidman, Benjamin D.; Lusk, Mark T.; Willson, Clinton S.; Wu, David T. (CSM); (LSU)
2011-08-09
Wet porous media are ubiquitous in nature as soils, rocks, plants, and bones, and in engineering settings such as oil production, ground stability, filtration and composites. Their physical and chemical behavior is governed by the distribution of liquid and interfaces between phases. Characterization of the interfacial distribution is mostly based on macroscopic experiments, aided by empirical formulae. We present an alternative computational paradigm utilizing a Monte Carlo algorithm to simulate interfaces in complex realistic pore geometries. The method agrees with analytical solutions available only for idealized pore geometries, and is in quantitative agreement with Micro X-ray Computed Tomography (microXCT), capillary pressure, and interfacial area measurements for natural soils. We demonstrate that this methodology predicts macroscopic properties such as the capillary pressure and air-liquid interface area versus liquid saturation based only on the pore size information from microXCT images and interfacial interaction energies. The generality of this method should allow simulation of capillarity in many porous materials.
Freezing in porous media: Phase behavior, dynamics and transport phenomena
Energy Technology Data Exchange (ETDEWEB)
Wettlaufer, John S. [Yale Univ., New Haven, CT (United States)
2012-12-21
This research was focused on developing the underlying framework for the mechanisms that control the nature of the solidification of a broad range of porous media. To encompass the scope of porous media under consideration we considered material ranging from a dilute colloidal suspension to a highly packed saturated host matrix with a known geometry. The basic physical processes that occur when the interstitial liquid phase solidifies revealed a host of surprises with a broad range of implications from geophysics to materials science and engineering. We now understand that ostensibly microscopic films of unfrozen liquid control both the equilibrium and transport properties of a highly packed saturated host matrix as well as a rather dilute colloidal suspension. However, our description of the effective medium behavior in these settings is rather different and this sets the stage for the future research based on our past results. Once the liquid phase of a saturated relatively densely packed material is frozen, there is a rich dynamical behavior of particles for example due to the directed motion driven by thermomolecular pressure gradients or the confined Brownian motion of the particles. In quite striking contrast, when one freezes a dilute suspension the behavior can be rather more like that of a binary alloy with the particles playing the role of a ``solute''. We probed such systems quantitatively by (i) using X ray photon correlation spectroscopy (XPCS) and Small Angle X-ray Scattering (SAXS) at the Advanced Photon Source at Argonne (ii) studying the Argonne cell in the laboratory using optical microscopy and imagery (because it is not directly visible while in the vacuum can). (3) analyzed the general transport phenomena within the framework of both irreversible thermodynamics and alloy solidification and (4) applied the results to the study of the redistribution of solid particles in a frozen interstitial material. This research has gone a long way
Mechanical Clogging Processes in Unconsolidated Porous Media Near Pumping Wells
de Zwart, B.; Schotting, R.; Hassanizadeh, M.
2003-12-01
In the Netherlands water supply companies produce over more than one billion cubic meters of drinking water every year. About 2500 water wells are used to pump up the groundwater from aquifers in the Dutch subsurface. More than 50% of these wells will encounter a number of technical problems during their lifetime. The main problem is the decrease in capacity due to well clogging. Clogging shows up after a number of operation years and results in extra, expensive cleaning operations and in early replacement of the pumping wells. This problem has been acknowledged by other industries, for example the metal, petroleum, beer industry and underground storage projects. Well clogging is the result of a number of interacting mechanisms creating a complex problem in the subsurface. In most clogging cases mechanical mechanisms are involved. A large number of studies have been performed to comprehend these processes. Investigations on mechanical processes are focused on transport of small particles through pores and deposition of particles due to physical or physical-chemical processes. After a period of deposition the particles plug the pores and decrease the permeability of the medium. Particle deposition in porous media is usually modelled using filtration theory. In order to get the dynamics of clogging this theory is not sufficient. The porous media is continuously altered due to deposition and mobilization. Therefore the capture characteristics will also continuously change and deposition rates will change in time. A new formula is derived to describe (re)mobilization of particles and allow changing deposition rates. This approach incorporates detachment and reattachment of deposited particles. This work also includes derivation of the filtration theory in radial coordinates. A comparison between the radial filtration theory and the new formula will be shown.
Multimodel framework for characterization of transport in porous media
Ciriello, Valentina; Edery, Yaniv; Guadagnini, Alberto; Berkowitz, Brian
2015-05-01
We consider modeling approaches to characterize solute transport in porous media, integrating them into a unique theoretical and experimental framework for model evaluation and data interpretation. To date, development of (conservative and reactive chemical) transport models and formulation of model calibration methods grounded on sensitivity-based collection of measurements have been pursued in parallel. Key questions that remain include: For a given set of measurements, which conceptual picture of the transport processes, as embodied in a mathematical model or models, is most appropriate? What are the most valuable space-time locations for solute concentration measurements, depending on the model selected? How is model parameter uncertainty propagated to model output, and how does this propagation affect model calibration? We address these questions by merging parallel streams of research—model formulation, reduction, calibration, sensitivity analysis, and discrimination—offering our view on an emerging framework that guides (i) selection of an appropriate number and location of time-dependent concentration measurements given a transport model and (ii) assessment (through discrimination criteria) of the relative benefit of applying any particular model from a set of several models. Our strategy is to employ metrics to quantify the relative contribution of each uncertain model parameter to the variability of the model output. We evaluate these metrics through construction of a surrogate (or "meta") transport model that has the additional benefit of enabling sensitivity analysis and model calibration at a highly reduced computational cost. We demonstrate the applicability of this framework, focusing on transport of reactive chemicals in laboratory-scale porous media.
Ferrofluid magnetoviscous control of wall flow channeling in porous media
Institute of Scientific and Technical Information of China (English)
Faal; Larachi
2007-01-01
[1]Bacri,J.C.,Perzynski,R.,Shliomis,M.I.,& Burde,G.I.(1995).Negative viscosity effect in a magnetic fluid.Physical Review Letters,75(11),2128-2131.[2]Felderhof,B.U.(2001).Flow of a ferrofluid down a tube in an oscillating magnetic field.Physical Review E,64(021508),1-7.[3]Khuzir,P.,Bossis,G.,Bashtovoi,V.,& Volkova,O.(2003).Flow of magnetorheological fluid through porous media.European Journal of Mechanics B/Fluids,22,331-343.[4]McTague,J.P.(1969).Magnetoviscosity of magnetic colloids.Journal of Chemical Physics,51,133-136.[5]Odenbach,S.(2003).Magnetic fluids-Suspensions of magnetic dipoles and their magnetic control.Journal of Physics:Condensed Matter,15,S 1497-S1508.[6]Rinaldi,C.,& Zahn,M.(2002).Effects of spin viscosity on ferrofluid flow profiles in alternating and rotating magnetic fields.Physics of Fluids,14,2847-2870.[7]Rosensweig,R.E.(1997).Ferrohydrodynamics.New York:Dover Publications.[8]Schumacher,K.R.,Sellien,I.,Knoke,G.S.,Cadet,T.,& Finlayson,B.A.(2003).Experiment and simulation of laminar and turbulent ferrofluid pipe flow in an oscillating magnetic field.Physical Review E,67(026308),1-11.[9]Shliomis,M.I.(1972).Effective viscosity of magnetic suspensions.Soviet Physics JETP,34,1291-1294.[10]Whitaker,S.(1999).Theory and applications of transport in porous media.Dordrecht:Kluwer Academic Press.[11]Zeuner,A.,Richter,R.,& Rehberg,I.(1998).Experiments on negative and positive magnetoviscosity in an alternating magnetic field.Physical Review E,58,62876293.
Staggered-Grid Finite Difference Method with Variable-Order Accuracy for Porous Media
Jinghuai Gao; Yijie Zhang
2013-01-01
The numerical modeling of wave field in porous media generally requires more computation time than that of acoustic or elastic media. Usually used finite difference methods adopt finite difference operators with fixed-order accuracy to calculate space derivatives for a heterogeneous medium. A finite difference scheme with variable-order accuracy for acoustic wave equation has been proposed to reduce the computation time. In this paper, we develop this scheme for wave equations in porous media...
Unstable infiltration fronts in porous media on laboratory scale
Schuetz, Cindi; Neuweiler, Insa
2014-05-01
Water flow and transport of substances in the unsaturated zone are important processes for the quality and quantity of water in the hydrologic cycle. The water movement through preferential paths is often much faster than standard models (e. g. Richards equation in homogeneous porous media) predict. One type/phenomenon of preferential flow can occur during water infiltration into coarse and/or dry porous media: the so-called gravity-driven fingering flow. To upscale the water content and to describe the averaged water fluxes in order to couple models of different spheres it is necessary to understand and to quantify the behavior of flow instabilities. We present different experiments of unstable infiltration in homogeneous and heterogeneous structures to analyze development and morphology of gravity-driven fingering flow on the laboratory scale. Experiments were carried out in two-dimensional and three-dimensional sand tanks as well as in larger two-dimensional sand tanks with homogeneous and heterogeneous filling of sand and glass beads. In the small systems, water content in the medium was measured at different times. We compare the experiments to prediction of theoretical approaches (e.g. Saffman and Taylor, 1958; Chuoke et al., 1959; Philip 1975a; White et al., 1976; Parlange and Hill, 1976a; Glass et al., 1989a; Glass et al., 1991; Wang et al., 1998c) that quantify properties of the gravity-driven fingers. We use hydraulic parameters needed for the theoretical predictions (the water-entry value (hwe), van Genuchten parameter (Wang et al., 1997, Wang et al., 2000) and saturated conductivity (Ks), van Genuchten parameter (Guarracino, 2007) to simplify the prediction of the finger properties and if necessary to identify a constant correction factor. We find in general that the finger properties correspond well to theoretical predictions. In heterogeneous settings, where fine inclusions are embedded into a coarse material, the finger properties do not change much
An FDTD algorithm for simulating light propagation in anisotropic dynamic gain media
Al-Jabr, A. A.
2014-05-02
Simulating light propagation in anisotropic dynamic gain media such as semiconductors and solid-state lasers using the finite difference time-domain FDTD technique is a tedious process, as many variables need to be evaluated in the same instant of time. The algorithm has to take care of the laser dynamic gain, rate equations, anisotropy and dispersion. In this paper, to the best of our knowledge, we present the first algorithm that solves this problem. The algorithm is based on separating calculations into independent layers and hence solving each problem in a layer of calculations. The anisotropic gain medium is presented and tested using a one-dimensional set-up. The algorithm is then used for the analysis of a two-dimensional problem.
Energy Technology Data Exchange (ETDEWEB)
Berryman, J.G.
2010-06-01
The mechanics of vertically layered porous media has some similarities to and some differences from the more typical layered analysis for purely elastic media. Assuming welded solid contact at the solid-solid interfaces implies the usual continuity conditions, which are continuity of the vertical (layering direction) stress components and the horizontal strain components. These conditions are valid for both elastic and poroelastic media. Differences arise through the conditions for the pore pressure and the increment of fluid content in the context of fluid-saturated porous media. The two distinct conditions most often considered between any pair of contiguous layers are: (1) an undrained fluid condition at the interface, meaning that the increment of fluid content is zero (i.e., {delta}{zeta} = 0), or (2) fluid pressure continuity at the interface, implying that the change in fluid pressure is zero across the interface (i.e., {delta}p{sub f} = 0). Depending on the types of measurements being made on the system and the pertinent boundary conditions for these measurements, either (or neither) of these two conditions might be directly pertinent. But these conditions are sufficient nevertheless to be used as thought experiments to determine the expected values of all the poroelastic coefficients. For quasi-static mechanical changes over long time periods, we expect drained conditions to hold, so the pressure must then be continuous. For high frequency wave propagation, the pore-fluid typically acts as if it were undrained (or very nearly so), with vanishing of the fluid increment at the boundaries being appropriate. Poroelastic analysis of both these end-member cases is discussed, and the general equations for a variety of applications to heterogeneous porous media are developed. In particular, effective stress for the fluid permeability of such poroelastic systems is considered; fluid permeabilities characteristic of granular media or tubular pore shapes are treated
Quantifying Biofilm in Porous Media Using Rock Physics Models
Alhadhrami, F. M.; Jaiswal, P.; Atekwana, E. A.
2012-12-01
Biofilm formation and growth in porous rocks can change their material properties such as porosity, permeability which in turn will impact fluid flow. Finding a non-intrusive method to quantify biofilms and their byproducts in rocks is a key to understanding and modeling bioclogging in porous media. Previous geophysical investigations have documented that seismic techniques are sensitive to biofilm growth. These studies pointed to the fact that microbial growth and biofilm formation induces heterogeneity in the seismic properties. Currently there are no rock physics models to explain these observations and to provide quantitative interpretation of the seismic data. Our objectives are to develop a new class of rock physics model that incorporate microbial processes and their effect on seismic properties. Using the assumption that biofilms can grow within pore-spaces or as a layer coating the mineral grains, P-wave velocity (Vp) and S-wave (Vs) velocity models were constructed using travel-time and waveform tomography technique. We used generic rock physics schematics to represent our rock system numerically. We simulated the arrival times as well as waveforms by treating biofilms either as fluid (filling pore spaces) or as part of matrix (coating sand grains). The preliminary results showed that there is a 1% change in Vp and 3% change in Vs when biofilms are represented discrete structures in pore spaces. On the other hand, a 30% change in Vp and 100% change in Vs was observed when biofilm was represented as part of matrix coating sand grains. Therefore, Vp and Vs changes are more rapid when biofilm grows as grain-coating phase. The significant change in Vs associated with biofilms suggests that shear velocity can be used as a diagnostic tool for imaging zones of bioclogging in the subsurface. The results obtained from this study have significant implications for the study of the rheological properties of biofilms in geological media. Other applications include
Direct, Dynamic Measurement of Interfacial Area within Porous Media
Energy Technology Data Exchange (ETDEWEB)
Crandall, Dustin; Ahmadi, Goodarz; Smith, Duane H.; Bromhal, Grant
2010-01-01
Standard models of two-phase flow in porous media have been shown to exhibit several shortcomings that might be partially overcome with a recently developed model based on thermodynamic principles (Hassanizadeh and Gray, 1990). This alternative two-phase flow model contains a set of new and non-standard parameters, including specific interfacial area. By incorporating interfacial area production, destruction, and propagation into functional relationships that describe the capillary pressure and saturation, a more physical model has been developed. Niessner and Hassanizadeh (2008) have examined this model numerically and have shown that the model captures saturation hysteresis with drainage/imbibition cycles. Several static experimental studies have been performed to examine the validity of this new thermodynamically based approach; these allow the determination of static parameters of the model. To date, no experimental studies have obtained information about the dynamic parameters required for the model. A new experimental porous flow cell has been constructed using stereolithography to study two-phase flow phenomena (Crandall et al. 2008). A novel image analysis tool was developed for an examination of the evolution of flow patterns during displacement experiments (Crandall et al. 2009). This analysis tool enables the direct quantification of interfacial area between fluids by matching known geometrical properties of the constructed flow cell with locations identified as interfaces from images of flowing fluids. Numerous images were obtained from two-phase experiments within the flow cell. The dynamic evolution of the fluid distribution and the fluid-fluid interface locations were determined by analyzing these images. In this paper, we give a brief introduction to the thermodynamically based two-phase flow model, review the properties of the stereolithography flow cell, and show how the image analysis procedure has been used to obtain dynamic parameters for the
Directory of Open Access Journals (Sweden)
Amit kumar Mishra
2015-01-01
Full Text Available In this paper, we have analyzed the effect of time periodic temperature modulation on convective stability in anisotropic porous cavity. The cavity is heated from below and cooled from above. A weakly non-linear stability analysis is done to find Nusselt number governing the heat transport. The infinitely small disturbances are expanded in terms of power series of amplitude of modulation. Analytically the nonautonomous Ginzburg- landau amplitude equation is obtained for the stationary mode of convection. The effects of various parameters like Vadasz number, mechanical and thermal anisotropic parameters, amplitude of oscillations, frequency of modulation and aspect ratio of the cavity on heat transport is studied and plotted graphically. It is observed that the heat transport can also be controlled by suitably adjusting the external and internal parameters of the system.
Experimental Study on Aero Conductivity of Porous Media
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
To study the variation pattern of aero conductivity of different porous media under low pressure conditions, three kinds of media are selected.These include sandy clay loam, fine sand, and medium sand, and air as fluid to conduct soil column ventilation tests.Pressure at both ends of the columns is measured under different ventilation flow rates during testing.The test results show that the aero conductivity, solved by Darcy's law, is not a constant.It is a variable, which increases first when air flow velocity is less than 0.258 7 cm/ s for sandy clay loam, 0.637 3 cm/s for fine sand and then decreases when air flow velocity is bigger than that with the increase of the ventilation flow rate when the medium is determined.By analyzing various factors that influence the flow resistance, the reasons for variation in aero conductivity are found as follows: first, the change of pore structure results in better ventilation; second, the relationship between pressure head loss and air flow velocity is nonlinear, and it is beyond the condition of the laminar flow domain to which Darcy's law can be applied, when the air flow rate increases to a certain value and the flow velocity is in the transition range to turbulent flow.
Dynamic Gelation of HPAM/Cr(III under Shear in an Agitator and Porous Media
Directory of Open Access Journals (Sweden)
Haiyang Yu
2015-11-01
Full Text Available Water shutoff and profile control is one of the most important technologies to enhance oil recovery. To ensure the success of this technology, the key is to accurately determine gelation time and gel strength during gel flow in porous media. The HPAM (Hydrolyzed PolyAcrylaMide system and redox system (sodium bichromate and sodium sulfite is widely used, whose static gelation time in ampoule bottles and porous media was determined, as well as the dynamic gelation time in an agitator and porous media. The shear rate was considered one of the major factors affecting gelation time. The results showed that the static gelation time in porous media was much longer than that in ampoule bottles. The Initial Gelation Time (IGT in porous media was two or three times that in ampoule bottles, while the final gelation time in porous media was six times that in ampoule bottles. Under shearing in an agitator, the gelation process was divided into four phases: induction, sudden increase, stability and decrease. With the increase in shear rate, gelation time was prolonged and gel strength decreased. There was a critical gelation shear rate, above which there was no gel formed. Shear had almost no influence on gel strength during the induction stage but in the process of sudden increase, shear could degrade gel strength sharply. The time of dynamic gelation in porous media was much longer than that of static gelation in porous media and ampoule bottles. When HPAM and RS (Redox System concentrations increased, the IGT of dynamic gelation in porous media was shortened.
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
When there exists anisotropy in underground media, elastic parameters of the observed coordinate possibly do not coincide with that of the natural coordinate. According to the theory that the density of potential energy, dissipating energy is independent of the coordinate, the relationship of elastic parameters between two coordinates is derived for two-phase anisotropic media. Then, pseudospectral method to solve wave equations of two-phase anisotropic media is derived. At last, we use this method to simulate wave propagation in two-phase anisotropic media, four types of waves are observed in the snapshots, i.e., fast P wave and slow P wave, fast S wave and slow S wave. Shear wave splitting, SV wave cusps and elastic wave reflection and transmission are also observed.
Humic acid transport in saturated porous media:Influence of flow velocity and influent concentration
Institute of Scientific and Technical Information of China (English)
Xiaorong Wei; Mingan Shao; Lina Du; Robert Horton
2014-01-01
Understanding the transport of humic acids (HAs) in porous media can provide important and practical evidence needed for accurate prediction of organic/inorganic contaminant transport in different environmental media and interfaces.A series of column transport experiments was conducted to evaluate the transport of HA in different porous media at different flow velocities and influent HA concentrations.Low flow velocity and influent concentration were found to favor the adsorption and deposition of HA onto sand grains packed into columns and to give higher equilibrium distribution coefficients and deposition rate coefficients,which resulted in an increased fraction of HA being retained in columns.Consequently,retardation factors were increased and the transport of HA through the columns was delayed.These results suggest that the transport of HA in porous media is primarily controlled by the attachment of HA to the solid matrix.Accordingly,this attachment should be considered in studies of HA behavior in porous media.
Waheed, Umair bin
2013-09-01
On several simple models of isotropic and anisotropic media, we have studied the accuracy of the two-point paraxial traveltime formula designed for the approximate calculation of the traveltime between points S\\' and R\\' located in the vicinity of points S and R on a reference ray. The reference ray may be situated in a 3D inhomogeneous isotropic or anisotropic medium with or without smooth curved interfaces. The twopoint paraxial traveltime formula has the form of the Taylor expansion of the two-point traveltime with respect to spatial Cartesian coordinates up to quadratic terms at points S and R on the reference ray. The constant term and the coefficients of the linear and quadratic terms are determined from quantities obtained from ray tracing and linear dynamic ray tracing along the reference ray. The use of linear dynamic ray tracing allows the evaluation of the quadratic terms in arbitrarily inhomogeneous media and, as shown by examples, it extends the region of accurate results around the reference ray between S and R (and even outside this interval) obtained with the linear terms only. Although the formula may be used for very general 3D models, we concentrated on simple 2D models of smoothly inhomogeneous isotropic and anisotropic (~8% and ~20% anisotropy) media only. On tests, in which we estimated twopoint traveltimes between a shifted source and a system of shifted receivers, we found that the formula may yield more accurate results than the numerical solution of an eikonal-based differential equation. The tests also indicated that the accuracy of the formula depends primarily on the length and the curvature of the reference ray and only weakly depends on anisotropy. The greater is the curvature of the reference ray, the narrower its vicinity, in which the formula yields accurate results.
Institute of Scientific and Technical Information of China (English)
刘颖; 刘凯欣
2004-01-01
According to generalized characteristic theory,a characteristic analysis for stress wave propagation in transversely isotropic fluid-saturated porous media was performed.The characteristic differential equations and compatibility relations along bicharacteristics were deduced and the analytical expressions for wave surfaces were obtained.The characteristic and shapes of the velocity surfaces and wave surfaces in the transversely isotropic fluid-saturated porous media were discussed in detail.The results also show that the characteristic equations for stress waves in pure solids are particular cases of the characteristic equations for fluid-saturated porous media.
Seepage Characteristics Study on Power-Law Fluid in Fractal Porous Media
Directory of Open Access Journals (Sweden)
Meijuan Yun
2014-01-01
Full Text Available We present fractal models for the flow rate, velocity, effective viscosity, apparent viscosity, and effective permeability for power-law fluid based on the fractal properties of porous media. The proposed expressions realize the quantitative description to the relation between the properties of the power-law fluid and the parameters of the microstructure of the porous media. The model predictions are compared with related data and good agreement between them is found. The analytical expressions will contribute to the revealing of physical principles for the power-law fluid flow in porous media.
Energy Technology Data Exchange (ETDEWEB)
Colwell, Frederick [Oregon State Univ., Corvallis, OR (United States); Wildenschild, Dorthe [Oregon State Univ., Corvallis, OR (United States); Wood, Brian [Oregon State Univ., Corvallis, OR (United States); Gerlach, Robin [Montana State Univ., Bozeman, MT (United States); Mitchell, Andrew [Montana State Univ., Bozeman, MT (United States); Redden, George [Idaho National Lab. (INL), Idaho Falls, ID (United States)
2014-08-29
The goal for this research was to understand how best to add compounds to receptive microbial communities in porous media in order to achieve optimal calcite precipitation in a volumetrically significant space and to understand the physiological health of the cells that are responsible for the calcite precipitation. The specific objectives were to: (1) develop better tools for visually examining biofilms in porous media and calcium carbonate precipitation being mediated by microbes in porous media, and (2) demonstrate the effectiveness of using that tool within a flow cell model system.
One-way acoustic mirror based on anisotropic zero-index media
Energy Technology Data Exchange (ETDEWEB)
Gu, Zhong-ming; Liang, Bin, E-mail: liangbin@nju.edu.cn, E-mail: jccheng@nju.edu.cn; Yang, Jing; Cheng, Jian-chun, E-mail: liangbin@nju.edu.cn, E-mail: jccheng@nju.edu.cn [Key Laboratory of Modern Acoustics, MOE, Institute of Acoustics, Department of Physics, Nanjing University, Nanjing 210093 (China); Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China); Zou, Xin-ye [Key Laboratory of Modern Acoustics, MOE, Institute of Acoustics, Department of Physics, Nanjing University, Nanjing 210093 (China); Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China); State Key Laboratory of Acoustics, Chinese Academy of Sciences, Beijing 100190 (China); Li, Yong [CNRS, Institut Jean Lamour, Vandoeuvre-lès-Nancy F-54506, France and Institut Jean Lamour, Université de Lorraine, Boulevard des Aiguillettes, BP: 70239, 54506 Vandoeuvre-lès-Nancy (France); Yang, Jun [Key Laboratory of Noise and Vibration Research, Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190 (China)
2015-11-23
We have designed a one-way acoustic mirror comprising anisotropic zero-index media. For acoustic beam incident at a particular angle, the designed structure behaves like a high-efficient mirror that redirects almost all the incident energy into another direction predicted by the Snell's law, while becoming virtually transparent to beams propagating reversely along this output path. Furthermore, the mirror can be tailored to work at arbitrary incident angle by simply adjusting its geometry. Our design, with undirectional reflection functionality and flexible working angle, may offer possibilities in space isolations and have deep implication in various scenarios like ultrasound imaging or noise control.
One-way acoustic mirror based on anisotropic zero-index media
International Nuclear Information System (INIS)
We have designed a one-way acoustic mirror comprising anisotropic zero-index media. For acoustic beam incident at a particular angle, the designed structure behaves like a high-efficient mirror that redirects almost all the incident energy into another direction predicted by the Snell's law, while becoming virtually transparent to beams propagating reversely along this output path. Furthermore, the mirror can be tailored to work at arbitrary incident angle by simply adjusting its geometry. Our design, with undirectional reflection functionality and flexible working angle, may offer possibilities in space isolations and have deep implication in various scenarios like ultrasound imaging or noise control
A joint velocity-concentration PDF method for tracer flow in heterogeneous porous media
Meyer, Daniel W.; Jenny, Patrick; Tchelepi, Hamdi A.
2010-12-01
The probability density function (PDF) of the local concentration of a contaminant, or tracer, is an important component of risk assessment in applications that involve flow in heterogeneous subsurface formations. In this paper, a novel joint velocity-concentration PDF method for tracer flow in highly heterogeneous porous media is introduced. The PDF formalism accounts for advective transport, pore-scale dispersion (PSD), and molecular diffusion. Low-order approximations (LOAs), which are usually obtained using a perturbation expansion, typically lead to Gaussian one-point velocity PDFs. Moreover, LOAs provide reasonable approximations for small log conductivity variances (i.e., σY2 Caroni and Fiorotto (2005) for saturated transport in velocity fields, which are stationary in space and time, for domains with σY2 = 0.05, 1, and 2 and Péclet numbers ranging from 100 to 10,000. PSD is modeled using constant anisotropic dispersion coefficients in both the reference MC computations and our PDF method.
Pepona, Marianna; Favier, Julien
2016-09-01
In this work, we propose a numerical framework to simulate fluid flows in interaction with moving porous media of complex geometry. It is based on the Lattice Boltzmann method including porous effects via a Brinkman-Forchheimer-Darcy force model coupled to the Immersed Boundary method to handle complex geometries and moving structures. The coupling algorithm is described in detail and it is validated on well-established literature test cases for both stationary and moving porous configurations. The proposed method is easy to implement and efficient in terms of CPU cost and memory management compared to alternative methods which can be used to deal with moving immersed porous media, e.g. re-meshing at each time step or use of a moving/chimera mesh. An overall good agreement was obtained with reference results, opening the way to the numerical simulation of moving porous media for flow control applications.
Experimental Study of Pressure Drop in Compressible Fluid through Porous Media
Energy Technology Data Exchange (ETDEWEB)
Seo, Min Kyo [Hanwha Corporation Defence R and D Center, Daejeon (Korea, Republic of); Kim, Do Hun; Seo, Chan Woo; Lee, Seoung Youn; Jang, Seok Pil; Koo, Jaye [Korea Aerospace Univ., Goyang (Korea, Republic of)
2013-08-15
This study proposes the characteristics of the pressure drop in a compressible fluid through porous media for application to a porous injector in a liquid rocket engine in order to improve the uniformity of the drop size distribution and the mixing performance of shear coaxial injectors. The fluid through the porous media is a Non-Darcy flow that shows a Nonlinear relation between the pressure drop and the velocity at high speed and high mass flow rate. The pressure drop of the Non-Darcy flow can be derived using the Ferrochrome equation that includes the losses of viscous and inertia resistance. The permeability and Erg un coefficient represented as a function of the pressure drop and pore size can be applied to the porous injector, where the fluid through the porous media is compressible. A generalized correlation between the pressure drop in relation to the pore size was derived.
Simulation of field-temperature effects in magnetic media using anisotropic Preisach models
Energy Technology Data Exchange (ETDEWEB)
Adly, A.A. [Cairo Univ., Giza (Egypt); Mayergoyz, I.D. [Univ. of Maryland, College Park, MD (United States). Electrical Engineering Dept.
1998-07-01
Prediction of temperature effects on magnetic properties has always been a topic of wide interest. Studying these effects may be particularly crucial for estimating the reliability of magnetic recording media and/or proper electrical machine core designs when significant working temperature variations are expected. In this paper, simulation of field-temperature effects in magnetic media is proposed by using a 2-D anisotropic Preisach-type hysteresis model. A technique for solving the identification problem of this model is developed. Experimental testing of the proposed model has been carried out on two different thin film hard disk samples. Comparison between measured and computed values indicate that the suggested model can lead to good qualitative, as well as quantitative, simulation results.
Energy Technology Data Exchange (ETDEWEB)
Mensch, Th.
2000-01-12
The seismic anisotropy causes in the Earth are known. The anisotropy characterization can provide valuable informations on the structure, lithology or eventual deformation processes in geological media. The orthorhombic symmetry allows a more complete description and representation of the anisotropy than the transversely isotropy symmetry usually assumed. Moreover this symmetry is potentially common in sedimentary basins, and particularly in fractured reservoir. In anisotropic media of arbitrary symmetry (triclinic), there is no simple analytic expressions on the phase slowness surface. The weak anisotropy assumption, often reasonable in geological media, makes perturbation techniques relevant. An approximate first order analytical expression of the qP-wave slowness surface is obtained. Using an adequate parameterization, the forward problem is solved by the ray theory. The Hamiltonian formulation introduces by a simple way ray equations in anisotropic media. The rays, travel time and its Fruchet derivatives expressions, valid to first order, are given for orthorhombic inhomogeneous media. Perturbation method applied to the ray theory allows the development of fast ray tracing in these media. Synthetic examples illustrate the accuracy and efficiency of the proposed approach. A tomographic method is developed. The travel time are inverted by minimizing, in term of least-square, the misfit between the observed and calculated travel times. The solution is approached iteratively by using a singular value decomposition algorithm. The inversion stability is assured by introducing a priori constraints. Synthetics examples show the need of an acquisition geometry well conceived to take account of anisotropy. (author)
Study of the mechanisms of the flame propagation and stabilization in porous media
Institute of Scientific and Technical Information of China (English)
2008-01-01
The CH4/air premixed gas combustion processes in porous media were numerically studied using the two-temperature reacting fluid model with dispersions and detailed chemical reaction mechanism GRI 3.0. The mechanisms of the propagation and stabilization of submerge flames and surface flames in porous media were illuminated distinctly by considering the magnitude of the terms in the two energy equations, analyzing the sensibility of flame propagation speed to flame location, heat exchange coefficient between gas and solid, thermal conductivity and radiative extinction coefficient of porous media. It was concluded that the propagation mechanism of a submerged flame is similar to that of a free flame with an additional preheat zone and that the surface-flame propagation mechanism in porous media is similar to that of a free flame with heat loss in reaction zone.
Saturated packed column and micromodel transport studies wereconducted to gain insightonmechanismsof colloid retention and release under unfavorable attachment conditions. The initial deposition of colloids in porous media was found to be a strongly coupled process that depended on solution chemistr...
Forced Convection Heat Transfer in Plate Channels Filled with Packed Beds or Sintered Porous Media
Institute of Scientific and Technical Information of China (English)
姜培学; 李勐; 任泽霈
2002-01-01
In the present work, forced convection heat transfer in plate channels filled with metallic or non-metallic particles (packed beds) or sintered porous media is simulated numerically using a thermal non-equilibrium model. The numerical simulation results are compared with experimental data. The difference between convection heat transfer in packed beds and in sintered porous media and the effects of the boundary condition assumptions are investigated. The results show that the numerical simulation of convection heat transfer of air or water in packed beds using the local thermal non-equilibrium model and the variable porosity model agrees well with the experimental data. The convection heat transfer coefficient in sintered porous media is much higher than that in packed beds. In the numerical simulation of convection heat transfer in sintered porous media, the boundary conditions on the wall should be that the particle temperatures are equal to the fluid temperature.
Study of the mechanisms of the flame propagation and stabilization in porous media
Institute of Scientific and Technical Information of China (English)
ZHAO PingHui; YE TaoHong; JIANG Hal; CHEN YiLiang
2008-01-01
The CH4/air premixed gas combustion processes in porous media were numeri-cally studied using the two-temperature reacting fluid model with dispersions and detailed chemical reaction mechanism GRI 3.0.The mechanisms of the propagation and stabilization of submerge flames and surface flames in porous media were illuminated distinctly by considering the magnitude of the terms in the two energy equations,analyzing the sensibility of flame propagation speed to flame location,heat exchange coefficient between gas and solid,thermal conductivity and radia-tive extinction coefficient of porous media.It was concluded that the propagation mechanism of a submerged flame is similar to that of a free flame with an additional preheat zone and that the surface-flame propagation mechanism in porous media is similar to that of a free flame with heat loss in reaction zone.
Geoelectric response of porous media in water and grout injection processes
Institute of Scientific and Technical Information of China (English)
孙强; 刘盛东; 姜春露; 王勃
2014-01-01
Significant changes in spontaneous potential and exciting currents are observed during water and grout injection in a simulated porous media. Obvious correlations between the seepage flow field and the electric field in the porous media are identified. In this work, a detailed experimental study of geoelectric field variation occurring in water migration was reported by analyzing water and grout injection processes in a simulated porous media. The spontaneous potential varies linearly with the thickness of unsaturated porous media. Very interestingly, the spontaneous potential generated in the second grout injection exhibits some“memory”of previous grouting paths. The decreases in spontaneous potential observed during grout injection is very probably due to that the spontaneous potential variations are primarily caused by electro-filtration potential, as indicated by the far larger viscosity of grout compared to that of water. The geoelectric response can be utilized to effectively identify the grouting paths in water-bearing rocks.
Study of the effects of stress sensitivity on the permeability and porosity of fractal porous media
Tan, Xiao-Hua; Li, Xiao-Ping; Liu, Jian-Yi; Zhang, Lie-Hui; Fan, Zhou
2015-10-01
Flow in porous media under stress is very important in various scientific and engineering fields. It has been shown that stress plays an important role in effect of permeability and porosity of porous media. In this work, novel predictive models for permeability and porosity of porous media considering stress sensitivity are developed based on the fractal theory and mechanics of materials. Every parameter in the proposed models has clear physical meaning. The proposed models are evaluated using previously published data for permeability and porosity measured in various natural materials. The predictions of permeability and porosity show good agreement with those obtained by the available experimental data and illustrate that the proposed models can be used to characterize the flow in porous media under stress accurately.
Mathematical and numerical modeling considerations for radionuclide ion migration in porous media
International Nuclear Information System (INIS)
The equations governing radionuclide transport in sorbing, porous media are presented using phenomenological coefficients. Both equilibrium controlled and simple rate controlled chemistry are summarized. Several simplified models are discussed. Finally, various numerical problems are considered. 25 references
Pore-network modeling of solute transport and biofilm growth in porous media
Qin, Chao Zhong; Hassanizadeh, S. Majid
2015-01-01
In this work, a pore-network (PN) model for solute transport and biofilm growth in porous media was developed. Compared to previous studies of biofilm growth, it has two new features. First, the constructed pore network gives a better representation of a porous medium. Second, instead of using a con
Wang, Lei; Wang, Xiaodong
2014-06-01
Resulting from the nature of anisotropy of coal media, it is a meaningful work to evaluate pressure transient behavior and flow characteristics within coals. In this article, a complete analytical model called the elliptical flow model is established by combining the theory of elliptical flow in anisotropic media and Fick's laws about the diffusion of coalbed methane. To investigate pressure transient behavior, analytical solutions were first obtained through introducing a series of special functions (Mathieu functions), which are extremely complex and are hard to calculate. Thus, a computer program was developed to establish type curves, on which the effects of the parameters, including anisotropy coefficient, storage coefficient, transfer coefficient and rate constant, were analyzed in detail. Calculative results show that the existence of anisotropy would cause great pressure depletion. To validate new analytical solutions, previous results were used to compare with the new results. It is found that a better agreement between the solutions obtained in this work and the literature was achieved. Finally, a case study is used to explain the effects of the parameters, including rock total compressibility coefficient, coal medium porosity and anisotropic permeability, sorption time constant, Langmuir volume and fluid viscosity, on bottom-hole pressure behavior. It is necessary to coordinate these parameters so as to reduce the pressure depletion.
Gao, Kai
2016-01-01
The conventional Perfectly Matched Layer (PML) is unstable for certain kinds of anisotropic media. This instability is intrinsic and independent of PML formulation or implementation. The Multi-axial PML (MPML) removes such instability using a nonzero damping coefficient in the direction parallel with the interface between a PML and the investigated domain. The damping ratio of MPML is the ratio between the damping coefficients along the directions parallel with and perpendicular to the interface between a PML and the investigated domain. No quantitative approach is available for obtaining these damping ratios for general anisotropic media. We develop a quantitative approach to determining optimal damping ratios to not only stabilize PMLs, but also minimize the artificial reflections from MPMLs. Numerical tests based on finite-difference method show that our new method can effectively provide a set of optimal MPML damping ratios for elastic-wave propagation in 2D and 3D general anisotropic media.
An empirical correlation for isothermal parallel plate channel completely filled with porous media
Directory of Open Access Journals (Sweden)
Hamdan Mohammad O.
2013-01-01
Full Text Available This study reports a simple empirical correlation for friction factor and Nusselt number for laminar, steady state, hydraulically and thermally fully developed flow in isothermal parallel plate channel completely filled with porous media. The study is carried out using a finite difference numerical analysis. The Darcy-Brinkman-Forchheimer model is used to model the flow inside the porous media. The empirical correlations are developed to relate friction factor and Nusselt number to Darcy and Forchheimer coefficient.
Determination of Effective Thermal Conductivity For Real Porous Media Using Fractal Theory
Institute of Scientific and Technical Information of China (English)
ChenYongping; ShiMingheng
1999-01-01
In this paper,using fractal theory,the geometric structure of real soil was described with ist section view and section particle area fractal dimension d of porous media was counted.The volumetric solid content and the relation between volumetric solid content and porous media particle arrangements as well as measure scale were obtainted.A heat conduction model was established and the effective thermal conductivity of real soil based on the volumetric solid content was calculated.
NEW STUDYING OF LATTICE BOLTZMANN METHOD FOR TWO-PHASE DRIVEN IN POROUS MEDIA
Institute of Scientific and Technical Information of China (English)
许友生; 刘慈群; 俞慧丹
2002-01-01
By using the interaction of particles, such as the physical principle of the same attract each other and the different repulse each other, a new model of Lattice Boltzmann to simulate the two-phase driven in porous media was discussed. The result shows effectively for the problem of two-phase driven in porous media. Furthermore, the method economizes on computer time, has less fiuctuation on boundary surface and takes no average measure.
An open-source toolbox for multiphase flow in porous media
Horgue, Pierre; Soulaine, Cyprien; Franc, Jacques; Guibert, Romain; Debenest, Gérald
2014-01-01
International audience Multiphase flow in porous media provides a wide range of applications: from the environmental understanding (aquifer, site-pollution) to industrial process improvements (oil production, waste management). Modeling of such flows involve specific volume-averaged equations and therefore specific computational fluid dynamics (CFD) tools. In this work, we develop a toolbox for modeling multiphase flow in porous media with OpenFOAM®, an open-source platform for CFD. The un...
FITTING OF THE DATA FOR DIFFUSION COEFFICIENTS IN UNSATURATED POROUS MEDIA
Energy Technology Data Exchange (ETDEWEB)
B. Bullard
1999-05-01
The purpose of this calculation is to evaluate diffusion coefficients in unsaturated porous media for use in the TSPA-VA analyses. Using experimental data, regression techniques were used to curve fit the diffusion coefficient in unsaturated porous media as a function of volumetric water content. This calculation substantiates the model fit used in Total System Performance Assessment-1995 An Evaluation of the Potential Yucca Mountain Repository (TSPA-1995), Section 6.5.4.
International Nuclear Information System (INIS)
We present a three-dimensional geometry model for tortuosity of streamlines in porous media with randomly placed cylindrical particles. The proposed model is expressed as functions of porosity and geometrical parameters with no empirical constant. This might be helpful for understanding the physical mechanism for tortuosity of streamlines in three-dimensional porous media. The model predictions are found to be in good agreement with the experimental data available
Quantitative evaluation of porous media wettability using NMR relaxometry.
Fleury, M; Deflandre, F
2003-01-01
We propose a new method to determine wettability indices from NMR relaxometry. The new method uses the sensitivity of low field NMR relaxometry to the fluid distribution in oil-water saturated porous media. The model is based on the existence of a surface relaxivity for both oil and water, allowing the determination of the amount of surface wetted either by oil or by water. The proposed NMR wettability index requires the measurement of relaxation time distribution at four different saturation states. At the irreducible water saturation, we determine the dominant relaxation time of oil in the presence of a small amount of water, and at the oil residual saturation, we determine the dominant relaxation time of water in the presence of a small amount of oil. At 100% water and 100% oil saturation, we determine the surface relaxivity ratio. The interaction of oil with the surface is also evidenced by the comparison of the spin-lattice (T1) and spin-locking (T1rho) relaxation times. The new NMR index agrees with standard wettability measurements based on drainage-imbibition capillary pressure curves (USBM test) in the range [-0.3-1]. PMID:12850740
Colloid suspension stability and transport through unsaturated porous media
Energy Technology Data Exchange (ETDEWEB)
McGraw, M.A.; Kaplan, D.I.
1997-04-01
Contaminant transport is traditionally modeled in a two-phase system: a mobile aqueous phase and an immobile solid phase. Over the last 15 years, there has been an increasing awareness of a third, mobile solid phase. This mobile solid phase, or mobile colloids, are organic or inorganic submicron-sized particles that move with groundwater flow. When colloids are present, the net effect on radionuclide transport is that radionuclides can move faster through the system. It is not known whether mobile colloids exist in the subsurface environment of the Hanford Site. Furthermore, it is not known if mobile colloids would likely exist in a plume emanating from a Low Level Waste (LLW) disposal site. No attempt was made in this study to ascertain whether colloids would form. Instead, experiments and calculations were conducted to evaluate the likelihood that colloids, if formed, would remain in suspension and move through saturated and unsaturated sediments. The objectives of this study were to evaluate three aspects of colloid-facilitated transport of radionuclides as they specifically relate to the LLW Performance Assessment. These objectives were: (1) determine if the chemical conditions likely to exist in the near and far field of the proposed disposal site are prone to induce flocculation (settling of colloids from suspension) or dispersion of naturally occurring Hanford colloids, (2) identify the important mechanisms likely involved in the removal of colloids from a Hanford sediment, and (3) determine if colloids can move through unsaturated porous media.
Mechanisms for two phase flow in porous media
International Nuclear Information System (INIS)
For a better understanding of transport mechanisms in soil for a system with two phases of immiscible liquids the physics of porous media gives again important contributions. In this report, the considerations mainly concentrate on horizontal transport. Our approach is based on the similarity solution of the transport equation which reduces a given nonlinear partial differential equation (PDE) to an ordinary differential equation (ODE). It can be seen, how dimensionless similarity solutions of the ODE depend, in addition to the similarity variable, on two parameters: - the capillary number Nc, giving the ratio of capillary forces and viscous forces, and - the ratio of the viscosities of the two liquid phases. It is shown, under which conditions different mechanisms of transport are to be expected, such as - a completely stable displacement or - an unstable displacement, related to viscous fingering (DLA, Diffusion Limited Aggregation) or to capillary fingering (IP, Invasion Percolation). These mechanisms are also strongly dependent on certain critical exponents (characteristic for DLA or IP). These relations are discussed in our report. Again, for some regions of saturation, mechanisms of displacement are either clearly dominated - by imbibition (e.g. water pushing oil) or - by drain (e.g. oil pushing water). Some of the results are also transformed again from the similarity solution of the ODE to a solution of the PDE (with space- and time coordinates). It is seen, that even with this somewhat simplified approach, we obtain a considerable spectrum of mechanisms. (orig.)
Temporal stability of superposed magnetic fluids in porous media
Energy Technology Data Exchange (ETDEWEB)
Zakaria, Kadry; Sirwah, Magdy A; Alkharashi, Sameh [Mathematics Department, Faculty of Science, Tanta University, Tanta (Egypt)
2008-02-15
The present work deals with the stability properties of time periodically streaming superposed magnetic fluids through porous media under the influence of an oblique alternating magnetic field. The system is composed of a middle fluid sheet of finite thickness embedded between two other bounded layers. The fluids are assumed to be incompressible and there are no volume charges in the layers of the fluids. Such configurations are of relevance in a variety of astrophysical and space configurations. The solutions of the linearized equations of motion and boundary conditions lead to deriving two more general simultaneous Mathieu equations of damping terms with complex coefficients. The method of multiple time scales is used to obtain approximate solutions and analyze the stability criteria for both the non-resonant and resonant cases and hence transition curves are obtained for such cases. The stability criteria are examined theoretically and numerically from which stability diagrams are obtained. It is found that the fluid sheet thickness plays a destabilizing role in the presence of a constant field and velocity, while the damping role is observed for the resonant cases. Dual roles are observed for the fluid velocity and the porosity in the stability criteria.
Colloid suspension stability and transport through unsaturated porous media
International Nuclear Information System (INIS)
Contaminant transport is traditionally modeled in a two-phase system: a mobile aqueous phase and an immobile solid phase. Over the last 15 years, there has been an increasing awareness of a third, mobile solid phase. This mobile solid phase, or mobile colloids, are organic or inorganic submicron-sized particles that move with groundwater flow. When colloids are present, the net effect on radionuclide transport is that radionuclides can move faster through the system. It is not known whether mobile colloids exist in the subsurface environment of the Hanford Site. Furthermore, it is not known if mobile colloids would likely exist in a plume emanating from a Low Level Waste (LLW) disposal site. No attempt was made in this study to ascertain whether colloids would form. Instead, experiments and calculations were conducted to evaluate the likelihood that colloids, if formed, would remain in suspension and move through saturated and unsaturated sediments. The objectives of this study were to evaluate three aspects of colloid-facilitated transport of radionuclides as they specifically relate to the LLW Performance Assessment. These objectives were: (1) determine if the chemical conditions likely to exist in the near and far field of the proposed disposal site are prone to induce flocculation (settling of colloids from suspension) or dispersion of naturally occurring Hanford colloids, (2) identify the important mechanisms likely involved in the removal of colloids from a Hanford sediment, and (3) determine if colloids can move through unsaturated porous media
Complexity Reduction of Multiphase Flows in Heterogeneous Porous Media
Ghommem, Mehdi
2015-04-22
In this paper, we apply mode decomposition and interpolatory projection methods to speed up simulations of two-phase flows in heterogeneous porous media. We propose intrusive and nonintrusive model-reduction approaches that enable a significant reduction in the size of the subsurface flow problem while capturing the behavior of the fully resolved solutions. In one approach, we use the dynamic mode decomposition. This approach does not require any modification of the reservoir simulation code but rather post-processes a set of global snapshots to identify the dynamically relevant structures associated with the flow behavior. In the second approach, we project the governing equations of the velocity and the pressure fields on the subspace spanned by their proper-orthogonal-decomposition modes. Furthermore, we use the discrete empirical interpolation method to approximate the mobility-related term in the global-system assembly and then reduce the online computational cost and make it independent of the fine grid. To show the effectiveness and usefulness of the aforementioned approaches, we consider the SPE-10 benchmark permeability field, and present a numerical example in two-phase flow. One can efficiently use the proposed model-reduction methods in the context of uncertainty quantification and production optimization.
Microfluidic investigation of the deposition of asphaltenes in porous media.
Hu, Chuntian; Morris, James E; Hartman, Ryan L
2014-06-21
The deposition of asphaltenes in porous media, an important problem in science and macromolecular engineering, was for the first time investigated in a transparent packed-bed microreactor (μPBR) with online analytics to generate high-throughput information. Residence time distributions of the μPBR before and after loading with ~29 μm quartz particles were measured using inline UV-Vis spectroscopy. Stable packings of quartz particles with porosity of ~40% and permeability of ~500 mD were obtained. The presence of the packing materials reduced dispersion under the same velocity via estimation of dispersion coefficients and the Bodenstein number. Reynolds number was observed to influence the asphaltene deposition mechanism. For larger Reynolds numbers, mechanical entrapment likely resulted in significant pressure drops for less pore volumes injected and less mass of asphaltenes being retained under the same maximum dimensionless pressure drop. The innovation of packed-bed microfluidics for investigations on asphaltene deposition mechanisms could contribute to society by bridging macromolecular science with microsystems. PMID:24777527
Study of the effects of stress sensitivity on the permeability and porosity of fractal porous media
International Nuclear Information System (INIS)
Flow in porous media under stress is very important in various scientific and engineering fields. It has been shown that stress plays an important role in effect of permeability and porosity of porous media. In this work, novel predictive models for permeability and porosity of porous media considering stress sensitivity are developed based on the fractal theory and mechanics of materials. Every parameter in the proposed models has clear physical meaning. The proposed models are evaluated using previously published data for permeability and porosity measured in various natural materials. The predictions of permeability and porosity show good agreement with those obtained by the available experimental data and illustrate that the proposed models can be used to characterize the flow in porous media under stress accurately. - Highlights: • Predictive models for permeability and porosity of porous media considering stress sensitivity are developed. • The fractal theory and mechanics of materials are used in these models. • The predictions of permeability and porosity show good agreement with those obtained by the available experimental data. • The proposed models can be used to characterize the flow in porous media under stress accurately
Influence of Dispersion on Transport of Tracer through Unsaturated Porous Media
Directory of Open Access Journals (Sweden)
T Bunsri
2008-01-01
Full Text Available The dispersion phenomenon has resulted from the various water flow magnitude and direction in porous media. The dissolved tracer tends to spread due to dispersion and then travel time of tracer through the porous media increases. In unsaturated porous media, dispersion coefficient varies with non-linear Darcy’s velocity and the water content. These effects observed in both of the laboratory scale sand and soil columns (20 cm. The unsaturated infiltration column and tracer tests have been used to interpret the relationships between Darcy’s velocity and the water content together with the dispersion coefficient. However, the dispersivity coefficient cannot be measured directly, it has to determine from advection-dispersion equation (ADE, which can be used to model the tracer transport in unsaturated porous media. The model was used to describe the non-linear functions of water contents and dispersivities for both porous media. The simulations have been verified that the dispersion of tracer through soil is higher than sand column and also travel time of tracer through soil is longer than sand column. Even though, soil has very low degree of pore velocity, the high dispersivity is observed in the simulations. The water content and tracer concentration profiles reveal that the increase of dispersivity induces the increase of flow path distance and the decrease of pore velocity. The maximum dispersivity was observed when the water content of porous media is relatively low; this leads the maximum of spreading of tracer.
Study of the effects of stress sensitivity on the permeability and porosity of fractal porous media
Energy Technology Data Exchange (ETDEWEB)
Tan, Xiao-Hua, E-mail: xiaohua-tan@163.com; Li, Xiao-Ping; Liu, Jian-Yi; Zhang, Lie-Hui; Fan, Zhou
2015-10-16
Flow in porous media under stress is very important in various scientific and engineering fields. It has been shown that stress plays an important role in effect of permeability and porosity of porous media. In this work, novel predictive models for permeability and porosity of porous media considering stress sensitivity are developed based on the fractal theory and mechanics of materials. Every parameter in the proposed models has clear physical meaning. The proposed models are evaluated using previously published data for permeability and porosity measured in various natural materials. The predictions of permeability and porosity show good agreement with those obtained by the available experimental data and illustrate that the proposed models can be used to characterize the flow in porous media under stress accurately. - Highlights: • Predictive models for permeability and porosity of porous media considering stress sensitivity are developed. • The fractal theory and mechanics of materials are used in these models. • The predictions of permeability and porosity show good agreement with those obtained by the available experimental data. • The proposed models can be used to characterize the flow in porous media under stress accurately.
Effect of sequential release of NAPLs on NAPL migration in porous media
Bang, Woohui; Yeo, In Wook
2016-04-01
NAPLs (Non-aqueous phase liquids) are common groundwater contaminants and are classified as LNAPLs (Light non-aqueous phase liquids) and DNAPLs (Dense non-aqueous phase liquids) according to relative density for water. Due to their low solubility in water, NAPLs remain for a long time in groundwater, and they pose a serious environmental problem. Therefore, understanding NAPLs migration in porous media is essential for effective NAPLs remediation. DNAPLs tend to move downward through the water table by gravity force because its density is higher than water. However, if DNAPLs do not have sufficient energy which breaks capillary force of porous media, they will just accumulate above capillary zone or water table. Mobile phase of LNAPLs rises and falls depending on fluctuation of water table, and it could change the wettability of porous media from hydrophilic to hydrophobic. This could impacts on the migration characteristics of subsequently-released DNAPLs. LNAPLs and DNAPLs are sometime disposed at the same place (for example, the Hill air force base, USA). Therefore, this study focuses on the effect of sequential release of NAPLs on NAPLs (in particular, DNAPL) migration in porous media. We have conducted laboratory experiments. Gasoline, which is known to change wettability of porous media from hydrophilic to intermediate, and TCE (Trichloroethylene) were used as LNAPL and DNAPL, respectively. Glass beads with the grain size of 1 mm and 2 mm were prepared for two sets of porous media. Gasoline and TCE was dyed for visualization. First, respective LNAPL and DNAPL of 10 ml were separately released into prepared porous media. For the grain size of 2 mm glass beads, LNAPL became buoyant above the water table, and DNAPL just moved downward through porous media. However, for the experiment with the grain size of 1 mm glass beads, NAPLs behaved very differently. DNAPL did not migrate downward below and just remained above the water table due to capillary pressure of
A Lattice Boltzmann Model for Fluid-Solid Coupling Heat Transfer in Fractal Porous Media
Institute of Scientific and Technical Information of China (English)
CAI Jun; HUAI Xiu-Lan
2009-01-01
We report a lattice Boltzmann model that can be used to simulate fluid-solid coupling heat transfer in fractal porous media.A numerical simulation is conducted to investigate the temperature evolution under different ratios of thermal conductivity of solid matrix of porous media to that of fluid.The accordance of our simulation results with the solutions from the conventional CFD method indicates the feasibility and the reliability for the developed lattice Boltzmann model to reveal the phenomena and rules of fluid-solid coupling heat transfer in complex porous structures.
Institute of Scientific and Technical Information of China (English)
XU You-Sheng; LIU Yang; HUANG Guo-Xiang
2004-01-01
@@ Digital images (DI) and lattice Boltzmann method (LBM) are used to characterize the threshold dynamic parameters of porous media. Two-dimensional representations of the porous structure are reconstructed from segmentation of digital images obtained from a series of tiny samples. The threshold pressure gradients and threshold Péclet numbers are researched on seven test samples by using LBM. Numerical results are in agreement with that obtained by integrating Darcy's law. The results also indicate that fluids can flow through porous media only if the fluid force is large enough to overcome threshold pressure gradient in porous media. One synthetic case is used to further illustrate the applicability of the proposed technique. In addition, the dynamical rules in our model are local, therefore it can be run on parallel computers with well computational efficiency.
Targeted Delivery by Smart Capsules for Controlling Two-phase Flow in Porous Media
Fan, J.; Weitz, D.
2015-12-01
Understanding and controlling two-phase flow in porous media are of particular importance to the relevant industry applications, such as enhanced oil recovery, CO2 sequestration, and groundwater remediation. We develop a variety of smart microcapsules that can deliver and release specific substances to the target location in the porous medium, and therefore change the fluid property or medium geometry at certain locations. In this talk, I will present two types of smart capsules for (a) delivering surfactant to the vicinity of oil-water interface and (b) delivering microgels to the high permeability region and therefore blocking the pore space there, respectively. We also show that flooding these two capsules into porous media effectively reduces the trapped oil and improves the homogeneity of the medium, respectively. Besides of its industrial applications, this technique also opens a new window to study the mechanism of two-phase flow in porous media.
A NEW INSTRUMENT FOR MEASURING LOCAL MOISTURE CONTENTS IN MOIST POROUS MEDIA
Institute of Scientific and Technical Information of China (English)
HAN Ji-tian; WANG Ji-hao; GUI Ke-ting; SHI Ming-heng
2005-01-01
A new instrument was developed for measuring the local moisture content in moist porous media based on the needle-type capacitance sensor and single-chip microprocessor technique. The working principle, the structure and characteristics of the hardware and software of the instrument were presented. The dynamic response characteristics and reliability of the instrument were experimentally determined. As an example, the instrument was employed to measure the heat and mass transport properties of a moist porous material. The experimental results show that the instrument can be used for measuring the local moisture content in moist porous media and would be an effective tool for determining the heat and mass transport properties in moist porous media.
Permeability analysis of fractured vuggy porous media based on homogenization theory
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
Based on the characteristics of fractured vuggy porous media,a novel mathematical model was proposed to model fluid flow in such media on fine scale,i.e.,the discrete fracture-vug network model.The new model consists of three systems:porous rock system,fracture system,and vug system.The fractures and vugs are embedded in porous rock,and the isolated vugs could be connected via the discrete fracture network.The flow in porous rock and fractures follows Darcy’s law,and the vugs system is free fluid region.Using a two-scale homogenization limit theory,we obtained a macroscopic Darcy’s law governing the media on coarse scale.The theoretical formula of the equivalent permeability of the fractured vuggy porous media was derived.The model and method of this paper were verified by some numerical examples.At the end the permeability of some fractured vuggy porous media with typical fracture-vug structures was analyzed.
Dynamics of water evaporation from saline porous media with mixed wettability
Bergstad, Mina; Shokri, Nima
2016-04-01
Understanding of the dynamics of salt transport and precipitation in porous media during evaporation is of crucial concern in various environmental and hydrological applications such as soil salinization, rock weathering, terrestrial ecosystem functioning, microbiological activities and biodiversity in vadose zone. Vegetation, plant growth and soil organisms can be severely limited in salt-affected land. This process is influenced by the complex interaction among atmospheric conditions, transport properties of porous media and properties of the evaporating solution (1-5). We investigated effects of mixed wettability conditions on salt precipitation during evaporation from saline porous media. To do so, we conducted a series of evaporation experiments with sand mixtures containing different fractions of hydrophobic grains saturated with NaCl solutions. The dynamics of salt precipitation at the surface of sand columns (mounted on digital balances to record the evaporation curves) as well as the displacement of the receding drying front (the interface between wet and partially wet zone) were recorded using an automatic imaging system at well-defined time intervals. The experiments were conducted with sand packs containing 0, 25, 40, 50, 65, and 80% fraction of hydrophobic grains. All experiments were conducted in an environmental chamber in which the relative humidity and ambient temperature were kept constant at 30% and 30 C, respectively. Our results show that partial wettability conditions had minor impacts on the evaporative mass losses from saline sand packs due to the presence of salt. This is significantly different than what is normally observed during evaporation from mixed wettability porous media saturated with pure water (6). In our experiments, increasing the fraction of hydrophobic grains did not result in any notable reduction of the evaporative mass losses from saline porous media. Our results show that the presence of hydrophobic grains on the surface
Rock Physics Models of Biofilm Growth in Porous Media
Jaiswal, P.; alhadhrami, F. M.; Atekwana, E. A.
2013-12-01
Recent studies suggest the potential to use acoustic techniques to image biofilm growth in porous media. Nonetheless the interpretation of the seismic response to biofilm growth and development remains speculative because of the lack of quantitative petrophysical models that can relate changes in biofilm saturation to changes in seismic attributes. Here, we report our efforts in developing quantitative rock physics models to biofilm saturation with increasing and decreasing P-wave velocity (VP) and amplitudes recorded in the Davis et al. [2010] physical scale experiment. We adapted rock physics models developed for modeling gas hydrates in unconsolidated sediments. Two distinct growth models, which appear to be a function of pore throat size, are needed to explain the experimental data. First, introduction of biofilm as an additional mineral grain in the sediment matrix (load-bearing mode) is needed to explain the increasing time-lapse VP. Second, introduction of biofilm as part of the pore fluid (pore-filling mode) is required to explain the decreasing time-lapse VP. To explain the time-lapse VP, up to 15% of the pore volume was required to be saturated with biofilm. The recorded seismic amplitudes, which can be expressed as a function of porosity, permeability and grain size, showed a monotonic time-lapse decay except on Day 3 at a few selected locations, where it increased. Since porosity changes are constrained by VP, amplitude increase could be modeled by increasing hydraulic conductivity. Time lapse VP at locations with increasing amplitudes suggest that these locations have a load-bearing growth style. We conclude that permeability can increase by up to 10% at low (~2%) biofilm saturation in load-bearing growth style due to the development of channels within the biofilm structure. Developing a rock physics model for the biofilm growth in general may help create a field guide for interpreting porosity and permeability changes in bioremediation, MEOR and
Flow of miscible and immiscible hydrocarbons in heterogeneous porous media
Energy Technology Data Exchange (ETDEWEB)
Butts, M.B.
1996-12-31
A series of large-scale two-dimensional physical model studies has been carried out in order to better understand and predict the multiphase flow of hydrocarbon contaminants and the release of the water-soluble fraction of such contaminants into the groundwater stream. The detailed measurements of the fluid saturations within the bulk hydrocarbon plume as well as the aqueous concentrations recorded downstream should provide a useful data set for testing and improving numerical models of both multiphase flow and transport. Predictions of a numerical model of immiscible multiphase flow developed in the petroleum industry were found to compare favourably with the observed oil plume for the case of an immiscible oil spill. Nevertheless, subtle layering within the experimental flume altered the long-term development of the oil plume in a manner not predicted by the numerical model. A stochastic model for three-dimensional, two-phase incompressible flow in heterogeneous soil and rock formations is developed. Analytical solutions for the resulting stochastic differential equations are derived for asymptotic flows using a perturbation approach. These solutions were used to derive general expressions for the large-scale (effective) properties for large-scale two-phase flow in porous media. An important observation from this analysis is that general large-scale flow in heterogeneous soils cannot be predicted on the basis of simple averages of the soil hydraulic properties alone. The large-scale capillary pressure saturation relation is evaluated for imbibition into a wet soil or rock formation. (EG) 194 refs.
Toward an improved understanding of multiphase flow in porous media
Muccino, Julia C.; Gray, William G.; Ferrand, Lin A.
1998-08-01
Physical description of multiphase flow in porous media ideally should be based on conservation principles. In practice, however, Darcy's law is employed as the foundation of multiphase flow studies. Darcy's law is an empirical surrogate for momentum conservation based on data obtained from experimental study of one-dimensional single-phase flow. In its original form [Darcy, 1856], Darcy's law contained a single, constant coefficient that depended on the properties of the medium. Since 1856, Darcy's relation has been heuristically and progressively altered by allowing this coefficient to be a spatially dependent, nonlinear function of fluid and solid phase properties, particularly of the quantities of these phases within the flow system. The shortcoming of this approach is that the governing flow equation is obtained by enhancing a simple empirical coefficient with complex functional dependencies rather than by simplifying general conservation principles. As a result, some of the important physical phenomena are not properly accounted for. Also, some assumptions intrinsic to the equations are overlooked, making accurate simulation more of an art than an entirely scientific exercise. A more general and more theoretically appealing approach to the derivation of conservation principles for multiphase flow has been evolving over the last 30 years. This approach employs a mathematical procedure for deriving conservation principles at the length scale of interest, followed by imposition of thermodynamic constraints to restrict the generality of these expressions. The product of this approach is a set of balance equations that provides a framework in which the assumptions inherent in a hypothesized model of multiphase flow are clearly stated. Requirements for more comprehensive and physically complete models can then be specified.
A New Numerical Solution of Fluid Flow in Stratigraphic Porous Media
Institute of Scientific and Technical Information of China (English)
XU You-Sheng; LI Hua-Mei; GUO Shang-Ping; HUANG Guo-Xiang
2004-01-01
A new numerical technique based on a lattice-Boltzmann method is presented for analyzing the fluid flow in stratigraphic porous media near the earth's surface. The results obtained for the relations between porosity, pressure,and velocity satisfy well the requirements of stratigraphic statistics and hence are helpful for a further study of the evolution of fluid flow in stratigraphic media.
Fractal scaling of effective diffusion coefficient of solute in porous media
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
Fractal approach is used to derive a power law relation betweeneffective diffusion coefficient of solute in porous media and the geometry parameter characterizing the media. The results are consistent with the empirical equations analogous to Archie'slaw and are expected to be applied to prediction of effective diffusion coefficient.
Measurement of colloidal phenomena during flow through refractive index matched porous media.
Roth, Eric J; Mont-Eton, Michael E; Gilbert, Benjamin; Lei, Tim C; Mays, David C
2015-11-01
Colloidal phenomena in porous media, natural or engineered, are important in a breadth of science and technology applications, but fundamental understanding is hampered by the difficulty in measuring colloid deposit morphology in situ. To partially address this need, this paper describes a static light scattering apparatus using a flow cell filled with refractive index matched (RIM) porous media, allowing real-time measurement of colloidal phenomena as a function of depth within the flow cell. A laser interacts with the colloids in the pore space and their structures, but not with the RIM media. The intensity of scattered light is measured as a function of scattering angle, which allows characterization of colloid deposit morphology as a fractal dimension and a radius of gyration. In parallel, fluid discharge rate and pressure drop are recorded to determine permeability, a key parameter for any application involving flow through porous media. This apparatus should prove useful in any application requiring characterization of colloidal phenomena within porous media. Additionally, this paper describes how to use granular Nafion as RIM porous media. PMID:26628117
2.5-D/3-D resistivity modelling in anisotropic media using Gaussian quadrature grids
Zhou, Bing; Greenhalgh, Mark; Greenhalgh, S. A.
2009-01-01
We present a new numerical scheme for 2.5-D/3-D direct current resistivity modelling in heterogeneous, anisotropic media. This method, named the `Gaussian quadrature grid' (GQG) method, cooperatively combines the solution of the Variational Principle of the partial differential equation, Gaussian quadrature abscissae and local cardinal functions so that it has the main advantages of the spectral element method. The formulation shows that the GQG method is a modification of the spectral element method but does not employ the constant elements or require the mesh generator to match the Earth's surface. This makes it much easier to deal with geological models having a 2-D/3-D complex topography than using traditional numerical methods. The GQG technique can achieve a similar convergence rate to the spectral element method. We show it transforms the 2.5-D/3-D resistivity modelling problem into a sparse and symmetric linear equation system that can be solved by an iterative or matrix inversion method. Comparison with analytic solutions for homogeneous isotropic and anisotropic models shows that the error depends on the Gaussian quadrature order (abscissa number) and the subdomain size. The higher the order or the smaller the subdomain size that is employed, the more accurate are the results obtained. Several other synthetic examples, both homogeneous and inhomogeneous, incorporating sloping, undulating and severe topography, are presented and found to yield results comparable to finite element solutions involving a dense mesh.
Institute of Scientific and Technical Information of China (English)
WANG Hui-fang; WANG Ming-yu
2012-01-01
Layered structures with upper porous and lower fractured media are widely distributed in the world.An experimental investigation on rainfall infiltration and solute transport in such layered structures can provide the necessary foundation for effectively preventing and forecasting water bursting in mines,controlling contamination of mine water,and accomplishing ecological restoration of mining areas.A typical physical model of the layered structures with porous and fractured media was created in this study.Then rainfall infiltration experiments were conducted after salt solution was sprayed on the surface of the layered structure.The volumetric water content and concentration of chlorine ions at different specified positions along the profile of the experiment system were measured in real-time.The experimental results showed that the lower fractured media,with a considerably higher permeability than that of the upper porous media,had significant effects on preventing water infiltration.Moreover,although the porous media were homogeneous statistically in the whole domain,spatial variations in the features of effluent concentrations with regards to time,or so called breakthrough curves,at various sampling points located at the horizontal plane in the porous media near the porous-fractured interface were observed,indicating the diversity of solute transport at small scales.Furthermore,the breakthrough curves of the outflow at the bottom,located beneath the underlying fractured rock,were able to capture and integrate features of the breakthrough curves of both the upper porous and fractured media,which exhibited multiple peaks,while the peak values were reduced one by one with time.
Heat Equation with Memory in Anisotropic and Non-Homogeneous Media
Institute of Scientific and Technical Information of China (English)
Jiongmin YONG; Xu ZHANG
2011-01-01
A modified Fourier's law in an anisotropic and non-homogeneous media results in a heat equation with memory, for which the memory kernel is matrix-valued and spatially dependent. Different conditions on the memory kernel lead to the equation being either a parabolic type or a hyperbolic type. Well-posedness of such a heat equation is established under some general and reasonable conditions. It is shown that the propagation speed for heat pulses could be either infinite or finite, depending on the different types of the memory kernels. Our analysis indicates that, in the framework of linear theory,heat equation with hyperbolic kernel is a more realistic model for the heat conduction, which might be of some interest in physics.
Rahman, S; Barnes, C H W
2005-01-01
We describe and evaluate a numerical solution strategy for simulating surface acoustic waves through semiconductor devices with complex geometries. This multi-physics problem is of particular relevance to the design of quantum electronic devices. The mathematical model consists of two coupled partial differential equations for the elastic wave propagation and the electric field, respectively, in anisotropic piezoelectric media. These equations are discretized by the finite element method in space and by a finite difference method in time. The latter method yields a convenient numerical decoupling of the governing equations. We describe how a computer implementation can utilize the decoupling and via object-oriented programming techniques reuse independent codes for the Poisson equation and the linear time-dependent elasticity equation. First we apply the simulator to a simplified model problem for verifying the implementation, and thereafter we show that the methodology is capable of simulating a real-world c...
Saad, Ali S.
2016-01-02
We study the convergence of a combined finite volume-nonconforming finite element scheme on general meshes for a partially miscible two-phase flow model in anisotropic porous media. This model includes capillary effects and exchange between the phases. The diffusion term, which can be anisotropic and heterogeneous, is discretized by piecewise linear nonconforming triangular finite elements. The other terms are discretized by means of a cell-centered finite volume scheme on a dual mesh. The relative permeability of each phase is decentered according to the sign of the velocity at the dual interface. The convergence of the scheme is proved thanks to an estimate on the two pressures which allows to show estimates on the discrete time and compactness results in the case of degenerate relative permeabilities. A key point in the scheme is to use particular averaging formula for the dissolution function arising in the diffusion term. We show also a simulation of hydrogen production in nuclear waste management. Numerical results are obtained by in-house numerical code. © 2015 Elsevier Ltd.
Cuenca, Jacques; Göransson, Peter
2012-08-01
This paper presents a method for simultaneously identifying both the elastic and anelastic properties of the porous frame of anisotropic open-cell foams. The approach is based on an inverse estimation procedure of the complex stiffness matrix of the frame by performing a model fit of a set of transfer functions of a sample of material subjected to compression excitation in vacuo. The material elastic properties are assumed to have orthotropic symmetry and the anelastic properties are described using a fractional-derivative model within the framework of an augmented Hooke's law. The inverse estimation problem is formulated as a numerical optimization procedure and solved using the globally convergent method of moving asymptotes. To show the feasibility of the approach a numerically generated target material is used here as a benchmark. It is shown that the method provides the full frequency-dependent orthotropic complex stiffness matrix within a reasonable degree of accuracy.
Effects of Heterogeneity on Transport of Graphene Oxide in Saturated and Unsaturated Porous Media
Dong, S.; Sun, Y.; Shi, X.; Wu, J.; Gao, B.
2015-12-01
Graphene oxide (GO) has received increasing attention in many fields with its wide applications and rapid growth in production. Therefore, it is expected that GO nanoparticles will inevitably be released into the subsurface and cause the environmental risk subsequently. In view of this, knowledge of the fate for GO in the vadose zone and groundwater systems is indispensable. So far most research has focused on the deposition and transport of GO nanoparticles in one-dimensional homogenous porous media; nonetheless, the complex heterogeneous system is extensively distributed in natural subsurface environment and may not be well represented by the homogeneous packed columns. However, little investigations have been directed toward understanding the transport of GO in heterogeneous porous media. The overarching objective of this study is to advance current understanding of GO transport in structured heterogeneous porous media. The saturated and unsaturated columns packed with different sand combinations and solution ionic strength, were used to examine the breakthrough behavior of GO in heterogeneous porous media. A two-domain model considering GO exchange between zones was developed to describe GO transport in structured, heterogeneous porous media. The experimental data indicate that volumetric moisture content and water flow are the critical factors that control GO transport in heterogeneous porous media. And higher ionic strength decrease the mobility of GO particles in both saturated and unsaturated heterogeneous pore media. Simulations of this two-domain nanoparticle transport model matched experimental breakthrough data well for all the experimental conditions. Experimental and model results show that under saturated conditions, both fast-flow and slow-flow domains affect colloid transport in heterogeneous media. Under unsaturated conditions, however, our results indicate that flows in the fast flow domain dominate the colloid transport and retention processes.
Hybrid finite volume scheme for a two-phase flow in heterogeneous porous media*
Directory of Open Access Journals (Sweden)
Brenner Konstantin
2012-04-01
Full Text Available We propose a finite volume method on general meshes for the numerical simulation of an incompressible and immiscible two-phase flow in porous media. We consider the case that can be written as a coupled system involving a degenerate parabolic convection-diffusion equation for the saturation together with a uniformly elliptic equation for the global pressure. The numerical scheme, which is implicit in time, allows computations in the case of a heterogeneous and anisotropic permeability tensor. The convective fluxes, which are non monotone with respect to the unknown saturation and discontinuous with respect to the space variables, are discretized by means of a special Godunov scheme. We prove the existence of a discrete solution which converges, along a subsequence, to a solution of the continuous problem. We present a number of numerical results in space dimension two, which confirm the efficiency of the numerical method. Nous proposons un schéma de volumes finis hybrides pour la discrétisation d’un problème d’écoulement diphasique incompressible et immiscible en milieu poreux. On suppose que ce problème a la forme d’une équation parabolique dégénérée de convection-diffusion en saturation couplée à une équation uniformément elliptique en pression. On considère un schéma implicite en temps, où les flux diffusifs sont discrétisés par la méthode des volumes finis hybride, ce qui permet de pouvoir traiter le cas d’un tenseur de perméabilité anisotrope et hétérogène sur un maillage très général, et l’on s’appuie sur un schéma de Godunov pour la discrétisation des flux convectifs, qui peuvent être non monotones et discontinus par rapport aux variables spatiales. On démontre l’existence d’une solution discrète, dont une sous-suite converge vers une solution faible du problème continu. On présente finalement des cas test bidimensionnels.
Directory of Open Access Journals (Sweden)
A. K. Acharya
2014-01-01
Full Text Available Free convective magnetohydrodynamics (MHD flow of a viscous incompressible and electrically conducting fluid past a hot vertical porous plate embedded in a porous medium in the presence of heat source has been studied in this paper. The temperature of the plate varies both in space and time. The main objective of this paper is to study the effect of porosity of the medium coupled with the variation of plate temperature with regard to space and in time. The effect of pertinent parameters characterizing the flow has been presented through the graphs. It is important to record that the presence of porous media has no significant contribution to the flow characteristics and viscous dissipation compensates for the heating and cooling of the plate due to convective current.
Energy Technology Data Exchange (ETDEWEB)
Cushman, J.H.
2000-06-01
Dynamic microbial attachment/detachment occurs in subsurface systems in response to changing environmental conditions caused by contaminant movement and degradation. Understanding the environmental conditions and mechanisms by which anaerobic bacteria partition between aqueous and solid phases is a critical requirement for designing and evaluating in situ bioremediation efforts. This interdisciplinary research project, of which we report only the Purdue contribution, provides fundamental information on the attachment/detachment dynamics of bacteria in heterogeneous porous media. Fundamental results from the Purdue collaboration are: (a) development of a matched-index method for obtaining 3-D Lagrangian trajectories of microbial sized particles transporting within porous media or microflow cells, (b) application of advanced numerical methods to optimally design a microflow cell for studying anaerobic bacterial attachment/detachment phenomena, (c) development of two types of models for simulating bacterial movement and attachment/detachment in microflow cells and natural porous media, (d) application of stochastic analysis to upscale pore scale microbial attachment/detachment models to natural heterogeneous porous media, and (e) evaluation of the role nonlocality plays in microbial dynamics in heterogeneous porous media.
Energy Technology Data Exchange (ETDEWEB)
Cushman, J.H.; Madilyn Fletcher
2000-06-01
Dynamic microbial attachment/detachment occurs in subsurface systems in response to changing environmental conditions caused by contaminant movement and degradation. Understanding the environmental conditions and mechanisms by which anaerobic bacteria partition between aqueous and solid phases is a critical requirement for designing and evaluating in situ bioremediation efforts. This interdisciplinary research project, of which we report only the Purdue contribution, provides fundamental information on the attachment/detachment dynamics of bacteria in heterogeneous porous media. Fundamental results from the Purdue collaboration are: (a) development of a matched-index method for obtaining 3-D Lagrangian trajectories of microbial sized particles transporting within porous media or microflow cells, (b) application of advanced numerical methods to optimally design a microflow cell for studying anaerobic bacterial attachment/detachment phenomena, (c) development of two types of models for simulating bacterial movement and attachment/detachment in microflow cells and natural porous media, (d) application of stochastic analysis to upscale pore scale microbial attachment/detachment models to natural heterogeneous porous media, and (e) evaluation of the role nonlocality plays in microbial dynamics in heterogeneous porous media
International Nuclear Information System (INIS)
Dynamic microbial attachment/detachment occurs in subsurface systems in response to changing environmental conditions caused by contaminant movement and degradation. Understanding the environmental conditions and mechanisms by which anaerobic bacteria partition between aqueous and solid phases is a critical requirement for designing and evaluating in situ bioremediation efforts. This interdisciplinary research project, of which we report only the Purdue contribution, provides fundamental information on the attachment/detachment dynamics of bacteria in heterogeneous porous media. Fundamental results from the Purdue collaboration are: (a) development of a matched-index method for obtaining 3-D Lagrangian trajectories of microbial sized particles transporting within porous media or microflow cells, (b) application of advanced numerical methods to optimally design a microflow cell for studying anaerobic bacterial attachment/detachment phenomena, (c) development of two types of models for simulating bacterial movement and attachment/detachment in microflow cells and natural porous media, (d) application of stochastic analysis to upscale pore scale microbial attachment/detachment models to natural heterogeneous porous media, and (e) evaluation of the role nonlocality plays in microbial dynamics in heterogeneous porous media
Analytical and experimental analysis of solute transport in heterogeneous porous media.
Wu, Lei; Gao, Bin; Tian, Yuan; Muñoz-Carpena, Rafael
2014-01-01
Knowledge of solute transport in heterogeneous porous media is crucial to monitor contaminant fate and transport in soil and groundwater systems. In this study, we present new findings from experimental and mathematical analysis to improve current understanding of solute transport in structured heterogeneous porous media. Three saturated columns packed with different sand combinations were used to examine the breakthrough behavior of bromide, a conservative tracer. Experimental results showed that bromide had different breakthrough responses in the three types of sand combinations, indicating that heterogeneity in hydraulic conductivity has a significant effect on the solute transport in structured heterogeneous porous media. Simulations from analytical solutions of a two-domain solute transport model matched experimental breakthrough data well for all the experimental conditions tested. Experimental and model results show that under saturated flow conditions, advection dominates solute transport in both fast-flow and slow-flow domains. The sand with larger hydraulic conductivity provided a preferential flow path for solute transport (fast-flow domain) that dominates the mass transfer in the heterogeneous porous media. Importantly, the transport in the slow-flow domain and mass exchange between the domains also contribute to the flow and solute transport processes and thus must be considered when investigating contaminant transport in heterogeneous porous media. PMID:24279625
Experimental investigation of magnetically driven flow of ferrofluids in porous media
Energy Technology Data Exchange (ETDEWEB)
Borglin, S.E.; Moridis, G.J.; Oldenburg, C.M.
1998-08-01
This report presents experimental results of the flow of ferrofluids in porous media to investigate the potential for precisely controlling fluid emplacement in porous media using magnetic fields. Ferrofluids are colloidal suspensions of magnetic particles stabilized in various carrier liquids. In the presence of an external magnetic field, the ferrofluid becomes magnetized as the particles align with the magnetic field. Potential applications of ferrofluids to subsurface contamination problems include magnetic guidance of reactants to contaminated target zones in the subsurface for in situ treatment or emplacement of containment barriers. Laboratory experiments of magnetically induced ferrofluid flow in porous media in this report demonstrate the potential for mobilizing ferrofluid and controlling fluid emplacement through control of the external magnetic field. The pressures measured in ferrofluid due to the attraction of ferrofluid to a permanent magnet agree well with calculated values. The results show that a predictable pressure gradient is produced in the fluid which is strong near the magnet and drops off quickly with distance. This pressure gradient drives the fluid through sand without significant loss of ferrofluid strength due to filtration or dilution. Flow visualization experiments of ferrofluid in water-filled horizontal Hele-Shaw cells demonstrate that ferrofluid obtains a consistent final arc-shaped configuration around the magnet regardless of initial configuration or flow path toward the magnet. Analogous experiments in actual porous media showed similar features and confirm the ability of ferrofluid to move through porous media by magnetic forces.
Evaporation of NaCl solution from porous media with mixed wettability
Bergstad, Mina; Shokri, Nima
2016-05-01
Evaporation of saline water from porous media is ubiquitous in many processes including soil salinization, crop production, and CO2 sequestration in deep saline acquirer. It is controlled by the transport properties of porous media, atmospheric conditions, and properties of the evaporating saline solution. In the present study, the effects of mixed wettability conditions on the general dynamics of water evaporation from porous media saturated with NaCl solution were investigated. To do so, we conducted a comprehensive series of evaporation experiments using sand mixtures containing different fractions of hydrophobic grains saturated with NaCl solutions. Our results showed that increasing fraction of hydrophobic grains in the mixed wettability sand pack had minor impact on the evaporative mass losses due to the presence of salt whose precipitation patterns were significantly influenced by the mixed wettability condition. Through macroscale and microscale investigations, we found formation of patchy efflorescence in the case of mixed wettability sand pack as opposed to crusty efflorescence in the case of completely hydrophilic porous media. Furthermore, the presence of salty water and hydrophobic grains in the sand pack significantly influenced the general dynamics and morphology of the receding drying front. Our results extend the understanding of the saline water evaporation from porous media with direct applications to various hydrological and engineering processes.
Laboratory Models of Thermal Convection in Porous Media
Cooper, C. A.; Breitmeyer, R.; Schumer, R.; Voepel, H.; Decker, D.
2011-12-01
Experiments have been conducted to measure the length and times scales of thermal plumes in laboratory porous media. A polycarbonate cell 1 m high x 75 cm wide x 2.54 cm deep filled with 3 mm glass beads is heated uniformly from the bottom using electrical heat tape. The heat tape is in direct contact with an aluminum alloy heat exchanger sandwiched between the two vertical plates, and a digital controller is used to maintain constant temperature. The upper boundary is kept at constant temperature by circulating cold water from a constant-temperature refrigerating bath through copper tubes in contact with the upper part of the cell. Flow is visualized by mixing a neutrally buoyant thermochromic liquid tracer in the working fluid (water and glycerin). TLCs are liquid crystals manufactured to change color as a function of temperature. Color change is repeatable and reversible with a response time to temperature change is less than 0.01 s. Image acquisition is done using a CCD camera, and three images are captured nearly simultaneously, each with a red, blue, or green filter over the camera lens. The three images are then combined to make a true color image. At each pixel in the image, hue is extracted and a calibration curve is developed to relate hue to temperature. In one experiment with a 10 degree C temperature difference between the upper and lower boundaries, the onset of convection began within 26 minutes, which is about half the time predicted by a scale analysis. The initial velocity of all plumes is on the order of 15 cm/hr, although some plumes stop moving before reaching the upper boundary of the cell. There are several reasons for plume deceleration: (1) As plumes travel vertically, they alter the initial temperature profile of the fluid such that the temperature field makes constant adjustments, which affects the dimensions, velocities, and interactions of the plumes; (2) adjacent plumes merge, resulting in a single larger plume; and (3) interactions
Compositional multiphase flow and transport in heterogeneous porous media
Energy Technology Data Exchange (ETDEWEB)
Huber, R.U.
2000-07-01
This work first treats the conceptual models for the description of multiphase flow processes in porous media. The thermodynamic laws are explained and the description and quantification of multi-fluid equilibria are discussed in order to account for fluid composition. The fully and weakly coupled approaches for the mathematical description of such flow processes with respect to systems consisting of two and three fluid phases as well as with respect to compositional single and multiphase systems are assessed. For the discretization of the two-phase flow equations node- and cell-centered finite volume methods and mixed and mixed-hybrid finite element approaches are applied. Based upon these methods five solution algorithms are developed. Four of these algorithms are based on the simultaneous solution of the discretized equations in combination with the Newton-Raphson technique. Methods 1 and 2 treat two- three-phase flow processes, Method 3 applies to the solution of partially miscible three-component systems while Method 4 is created for three-phase three-component systems. The latter method uses a variable substitution dependent on the local presence of the fluid phases. Method 5 is based on the IMPES/IMPESC concept. The time-implicit pressure equation is discretized with the mixed-hybrid finite element method. The saturation and concentration equations, respectively, are solved with a cell-centered finite volume scheme. The developed algorithms are applied to the two- and three-phase Buckley-Leverett problems. A partitioning interwell tracer test is simulated. The propagation behavior of nonaqueous phase liquids (NAPLs) in the saturated and unsaturated ground zone under the influence of heterogeneities are examined. In addition, a larger-scale experiment is simulated, which involves an injection of trichloroethylene into the subsurface and the subsequent distribution. Here, the development of a dissolved contaminant plume as well as the behavior of organic
Numerical modeling of boiling heat transfer in porous media
International Nuclear Information System (INIS)
Theoretical models were developed and validated to investigate boiling heat transfer in porous layers with and without the presence of chimneys. The critical heat flux and distributions of temperature, liquid saturation, liquid and vapor pressures, and liquid and vapor velocities were predicted numerically under typical PWR conditions. The results indicate that a porous layer produces a higher heat transfer coefficient in the nucleate boiling regime, as is well-known, and could potentially yield a much higher critical heat flux than a plain surface does. Moreover, a chimney-type porous layer can have a better thermal performance, i.e., heat transfer coefficient and critical heat flux than a homogeneous one, primarily due to the presence of chimneys providing pathways for vapor to escape from the porous layer with less resistance
Zhong-yan Liu; Huan-zhen Chen
2014-01-01
By choosing the trial function space to the immersed finite element space and the test function space to be piecewise constant function space, we develop a discontinuous Galerkin immersed finite volume element method to solve numerically a kind of anisotropic diffusion models governed by the elliptic interface problems with discontinuous tensor-conductivity. The existence and uniqueness of the discrete scheme are proved, and an optimal-order energy-norm estimate and ${L}^{2}$ -norm estimate f...
Ortiz, Aurélie U.; Boutin, Anne; Fuchs, Alain H; Coudert, François-Xavier
2012-01-01
We performed ab initio calculations of the elastic constants of five flexible metal-organic frameworks: MIL-53(Al), MIL-53(Ga), MIL-47 and the square and lozenge structures of DMOF-1. Tensorial analysis of the elastic constants reveal a highly anisotropic elastic behavior, some deformation directions exhibiting very low Young's modulus and shear modulus. This anisotropy can reach a 400:1 ratio between the most rigid and weakest directions, in stark contrast with the case of non-flexible MOFs ...
Gas transport in tight porous media Gas kinetic approach
DEFF Research Database (Denmark)
Shapiro, Alexander; Wesselingh, Johannes
2008-01-01
We describe the flow of gas in a porous medium in the kinetic regime, where the viscous flow structure is not formed in separate pores. Special attention is paid to the dense kinetic regime, where the interactions within the gas are as important as the interaction with the porous medium. The tran....... The role of the thermal gradient in the transport law is clarified. (c) 2007 Elsevier B.V. All rights reserved....
Institute of Scientific and Technical Information of China (English)
李锡夔; 张俊波; 张洪武
2001-01-01
In the present work a model based on the Biot theory for simulating coupled hydrodynamic behavior in saturated porous media is utilized with integration of the inertial coupling effect between the solid-fluid phases of the media into the model. The non-associated Drucker-Prager criterion to describe nonlinear constitutive behavior of pressure dependent elasto-plasticity for the media is particularly considered. With no consideration of compressibility of solid grains and the pore fluid, the discontinuity and instability of the wave propagation in saturated porous media are analyzed for the plane strain problems in detail. The critical conditions of stationary discontinuity and flutter instability in the wave propagation are given.The results and conclusions obtained by the present work will provide some bases or clues for overcoming the difficulties in numerical modeling of wave propagation in the media subjected to dynamic loading.
Yuwen, Tairan; Post, Carol Beth; Skrynnikov, Nikolai R
2011-09-01
Many proteins have modular design with multiple globular domains connected via flexible linkers. As a simple model of such system, we study a tandem construct consisting of two identical SH3 domains and a variable-length Gly/Ser linker. When the linker is short, this construct represents a dumbbell-shaped molecule with limited amount of domain-domain mobility. Due to its elongated shape, this molecule efficiently aligns in steric alignment media. As the length of the linker increases, the two domains become effectively uncoupled and begin to behave as independent entities. Consequently, their degree of alignment drops, approaching that found in the (near-spherical) isolated SH3 domains. To model the dependence of alignment parameters on the length of the interdomain linker, we have generated in silico a series of conformational ensembles representing SH3 tandems with different linker length. These ensembles were subsequently used as input for alignment prediction software PALES. The predicted alignment tensors were compared with the results of experimental measurements using a series of tandem-SH3 samples in PEG/hexanol alignment media. This comparison broadly confirmed the expected trends. At the same time, it has been found that the isolated SH3 domain aligns much stronger than expected. This finding can be attributed to complex morphology of the PEG/hexanol media and/or to weak site-specific interactions between the protein and the media. In the latter case, there are strong indications that electrostatic interactions may play a role. The fact that PEG/hexanol does not behave as a simple steric media should serve as a caution for studies that use PALES as a quantitative prediction tool (especially for disordered proteins). Further progress in this area depends on our ability to accurately model the anisotropic media and its site-specific interactions with protein molecules. Once this ability is improved, it should be possible to use the alignment parameters as a
International Nuclear Information System (INIS)
Many proteins have modular design with multiple globular domains connected via flexible linkers. As a simple model of such system, we study a tandem construct consisting of two identical SH3 domains and a variable-length Gly/Ser linker. When the linker is short, this construct represents a dumbbell-shaped molecule with limited amount of domain–domain mobility. Due to its elongated shape, this molecule efficiently aligns in steric alignment media. As the length of the linker increases, the two domains become effectively uncoupled and begin to behave as independent entities. Consequently, their degree of alignment drops, approaching that found in the (near-spherical) isolated SH3 domains. To model the dependence of alignment parameters on the length of the interdomain linker, we have generated in silico a series of conformational ensembles representing SH3 tandems with different linker length. These ensembles were subsequently used as input for alignment prediction software PALES. The predicted alignment tensors were compared with the results of experimental measurements using a series of tandem-SH3 samples in PEG/hexanol alignment media. This comparison broadly confirmed the expected trends. At the same time, it has been found that the isolated SH3 domain aligns much stronger than expected. This finding can be attributed to complex morphology of the PEG/hexanol media and/or to weak site-specific interactions between the protein and the media. In the latter case, there are strong indications that electrostatic interactions may play a role. The fact that PEG/hexanol does not behave as a simple steric media should serve as a caution for studies that use PALES as a quantitative prediction tool (especially for disordered proteins). Further progress in this area depends on our ability to accurately model the anisotropic media and its site-specific interactions with protein molecules. Once this ability is improved, it should be possible to use the alignment parameters as
Influence of the Gas-Water Interface on Transport of Microorganisms through Unsaturated Porous Media
Wan, Jiamin; Wilson, John L.; Kieft, Thomas L.
1994-01-01
In this article, a new mechanism influencing the transport of microorganisms through unsaturated porous media is examined, and a new method for directly visualizing bacterial behavior within a porous medium under controlled chemical and flow conditions is introduced. Resting cells of hydrophilic and relatively hydrophobic bacterial strains isolated from groundwater were used as model microorganisms. The degree of hydrophobicity was determined by contact-angle measurements. Glass micromodels a...
Potential of Porous-Media Combustion Technology as Applied to Internal Combustion Engines
Miroslaw Weclas
2010-01-01
The paper summarizes the knowledge concerning porous media combustion techniques as applied in engines. One of most important reasons of this review is to introduce this still not well known technology to researchers doing with internal combustion engine processes, thermal engines, reactor thermodynamics, combustion, and material science. The paper gives an overview of possible applications of a highly porous open cell structures to in-cylinder processes. This application means utilization of...
Modeling the Impact of Fracture Growth on Fluid Displacements in Deformable Porous Media
Santillán, D.; Cueto-Felgueroso, L.; Juanes, R.
2015-12-01
Coupled flow and geomechanics is a critical research challenge in engineering and the geosciences. The flow of a fluid through a deformable porous media is present in manyenvironmental, industrial, and biological processes,such as the removal of pollutants from underground water bodies, enhanced geothermal systems, unconventional hydrocarbon resources or enhanced oil recovery techniques. However, the injection of a fluid can generate or propagate fractures, which are preferential flow paths. Using numerical simulation, we study the interplay between injection and rock mechanics, and elucidate fracture propagation as a function of injection rate, initial crack topology and mechanical rock properties. Finally, we discuss the role of fracture growth on fluid displacements in porous media. Figure: An example of fracture (in red) propagated in a porous media (in blue)
Measurement of Fluid Flow in Pipe and Porous Media by High-Resolution Magnetic Resonance Imaging
Institute of Scientific and Technical Information of China (English)
JIANG Lan-lan; SONG Yong-chen; LIU Yu; DOU Bin-lin; ZHU Ning-jun; ZHAO Jia-fei; BULITI Abudula
2012-01-01
The objective of this study is to understand the process of fluid flow in pipe and porous media with different pore structures.High-resolution Magnetic Resonance Imaging (MRI) technique was used to visualize the pore structure and measure fluid flow.The porous media was formed by packed bed of glass beads.Flow measurement was carried out by a modified spin echo sequence.The results show that the velocity distribution in pipe is annular and the linear relation between MRI velocity and actual velocity is found in pipe flow measurement.The flow distribution in porous media is rather heterogeneous,and it is consistent with heterogeneous pore structure.The flow through pores with the high volume flow rate is determined largely by geometrical effects such as pore size and cross-sectional area.
Investigation of Resistivity of Saturated Porous Media with Lattice Boltzmann Method
Institute of Scientific and Technical Information of China (English)
YUE Wen-Zheng; TAO Guo; ZHU Ke-Qin
2004-01-01
The lattice Boltzmann method is employed to study the electrical transport properties of saturated porous media.Electrical current flow through the porous media is simulated and the relationship between resistivity index and water saturation is derived. It is found that this kind of relation is not a straight line as described by the Archie equation with the parameter n being a constant in a log-log scale. A new equation is thus developed to formulate this relation with n being a function of porosity and water saturation. The comparisons between the results by lattice Boltzmann and by the laboratory experiments on rock samples demonstrate that this numerical method can provide an alternative way for the expensive laboratory experiments to investigate the electrical transport properties of saturated porous media and can be used to explore micro mechanisms more conveniently.
ONSET CONDITION OF STRAIN LOCALIZATION IN MATRIX OF SATURATED POROUS MEDIA
Institute of Scientific and Technical Information of China (English)
ZHAO Ji-sheng; TAO Xia-xin; SHI Li-jing; OU Jin-ping
2005-01-01
Based on governing equations of saturated porous media and Liapunov's stability here, onset conditions matrix of porous media used by solid stress and Terzaghi's effective stress constitutive description under seepage flow state, are presented, which have different forms with different representation of the solid phase, matrix or skeleton, constitutive model of porous media. The main difference relates with how to describe the interaction between solid phase and liquid phase in constitutive model. The derived onset condition of strain localization under Terzaghi's effective stress description can be used to interpret different failure types, piping effect, landslides and mudflows, by means of the type and the magnitude ratio of relative movement between solid phase and liquid phase. Examples here illuminate the onset condition of how to work.
Modelling multiphase flow inside the porous media of a polymer electrolyte membrane fuel cell
DEFF Research Database (Denmark)
Berning, Torsten; Kær, Søren Knudsen
2011-01-01
Transport processes inside polymer electrolyte membrane fuel cells (PEMFC’s) are highly complex and involve convective and diffusive multiphase, multispecies flow through porous media along with heat and mass transfer and electrochemical reactions in conjunction with water transport through...... an electrolyte membrane. We will present a computational model of a PEMFC with focus on capillary transport of water through the porous layers and phase change and discuss the impact of the liquid phase boundary condition between the porous gas diffusion layer and the flow channels, where water droplets can...
Wei, Changfu
2001-09-01
The mechanical behavior of porous media such as geomaterials is largely governed by the interactions of the solid skeleton (or grains) with the fluids existing in the pores. These interactions occur through the interfaces between bulk components. Traditional analysis procedures of porous media, based on the principle of effective stress and Darcy's law, commonly fail to account for these interactions. In this dissertation, a continuum theory of multiphase porous media is developed, capable of rigorously characterizing the interactions among bulk components. Central to the theory is the implementation of the dynamic compatibility conditions that microscopically represent the constraints on the pressure jumps through interfaces. It is shown that Terzaghi's effective stress and capillary pressure can be characterized within a common framework. Within this context, a theoretical framework for poroelastoplasticity is developed, allowing the hysteresis in capillary pressure and plastic deformation of skeleton to be simulated in a hierarchical way. It is found that the mixture theory-based models of porous media can be linked with Biot's poroelasticity theory. A linear model based on the proposed theory is developed and used to analyze the propagation of acoustic waves in unsaturated soils and favorable comparisons to experimental results are obtained. A finite element procedure is developed and implemented into a computer code (called U_DYSAC2) for elastoplastic static and dynamic analyses of saturated and unsaturated porous media. Numerical examples including wave propagation, two-phase flow, consolidation, and seismic behavior of an embankment are presented. These examples show the capability of the theory for modeling a wide variety of behaviors of porous media.
Dynamics of barite growth in porous media quantified by in situ synchrotron X-ray tomography
Godinho, jose; Gerke, kirill
2016-04-01
Current models used to formulate mineral sequestration strategies of dissolved contaminants in the bedrock often neglect the effect of confinement and the variation of reactive surface area with time. In this work, in situ synchrotron X-ray micro-tomography is used to quantify barite growth rates in a micro-porous structure as a function of time during 13.5 hours with a resolution of 1 μm. Additionally, the 3D porous network at different time frames are used to simulate the flow velocities and calculate the permeability evolution during the experiment. The kinetics of barite growth under porous confinement is compared with the kinetics of barite growth on free surfaces in the same fluid composition. Results are discussed in terms of surface area normalization and the evolution of flow velocities as crystals fill the porous structure. During the initial hours the growth rate measured in porous media is similar to the growth rate on free surfaces. However, as the thinner flow paths clog the growth rate progressively decreases, which is correlated to a decrease of local flow velocity. The largest pores remain open, enabling growth to continue throughout the structure. Quantifying the dynamics of mineral precipitation kinetics in situ in 4D, has revealed the importance of using a time dependent reactive surface area and accounting for the local properties of the porous network, when formulating predictive models of mineral precipitation in porous media.
Institute of Scientific and Technical Information of China (English)
Zhang Xuemin; Li Jinping; Wu Qingbai; Wang Chunlong; Nan Junhu
2015-01-01
Porous medium has an obvious effect on the formation of carbon dioxide hydrate. In order to study the character-istics of CO2 hydrate formation in porous medium below the freezing point, the experiment of CO2 hydrate formation was conducted in a high-pressure 1.8-L cell in the presence of porous media with a particle size of 380μm, 500μm and 700μm, respectively. The test results showed that the porous medium had an important inlfuence on the process of CO2 hydrate for-mation below the freezing point. Compared with porous media with a particle size of 500μm and 700μm, respectively, the average hydrate formation rate and gas storage capacity of carbon dioxide hydrate in the porous medium with a particle size of 380μm attained 0.016 14 mol/h and 65.094 L/L, respectively. The results also indicated that, within a certain range of particle sizes, the smaller the particle size of porous medium was, the larger the average hydrate formation rate and the gas storage capacity of CO2 hydrate during the process of hydrate formation would be.
Ziazi, R. M.; Liburdy, J.; Apte, S.; Wood, B. D.
2015-12-01
The sequential transient regime of the flow through randomly packed porous media has been observed experimentally from steady inertial to turbulent flow. Considering the inherent constraints in visualization and measurements in porous media, the characterization has been performed using time resolved PIV in a randomly packed ordered array of spheres with uniform size. The size of the spheres are 15 mm and the pore Reynolds numbers are set to be 300, 500, and 900. The test bed has a cross-section of 70×70 mm and a height of 15mm. In addition to the difficult accessibility to the interrogation window, the challenges of visualizing the flow in this porous structure is matching of refractive indices of the fluid and solid phase as slight mismatches have been shown to cause significant tracking errors. The 2-D velocity field has been captured at discrete planar locations along the optical axis through the test bed to study the physics and statistics of the flow. Variations occur in the imaging magnification, and if not taken into consideration may lead to increased error. This study addresses three forms of error in PIV as they pertain to porous media flow: tracking error, bias error due to displacement gradients and perspective error. The bias error due to displacement gradients was evaluated from correlation peak width. Direct Numerical Simulation is also being performed to investigate the transitional and turbulent flow in porous media in detail.
On the Study of Lifting Mechanism of a Soft Porous Media under Fast Compression
Wu, Qianhong; Santhanam, S.; Nathan, R.; Vucbmss Team
2015-11-01
Fluid flow in a soft porous media under fast compressions is widely observed in biological systems and industrial applications. Despite of much progress, it remains unclear for the lifting mechanisms of the porous media due to the lack of complete experimental verifications of theoretical models. We report herein a unique approach to treat the limitation. The permeability of a synthetic fibrous porous media as a function of its compression was first measured. The material was then employed in a dynamic compression experiment using a porous-walled cylinder piston apparatus. The obtained transient compression of the porous media and the aforementioned permeability data were applied in different theoretical models for the pore pressure generation, which conclusively proved the validity of the consolidation theory developed by Wu et al. (JFM, 542, 281, 2005). Furthermore, the solid phase lifting force was separated from the total reaction force and was characterized by a new viscoelastic model, containing a nonlinear spring in conjunction with a linear viscoelastic Generalized Maxwell mechanical module. Excellent agreement was obtained between the experiment and the theory. Thus, the lifting forces from both the fluid and the solid were determined. This project is supported by NSF Grant 1511096.
Multi-level adaptive simulation of transient two-phase flow in heterogeneous porous media
Chueh, C.C.
2010-10-01
An implicit pressure and explicit saturation (IMPES) finite element method (FEM) incorporating a multi-level shock-type adaptive refinement technique is presented and applied to investigate transient two-phase flow in porous media. Local adaptive mesh refinement is implemented seamlessly with state-of-the-art artificial diffusion stabilization allowing simulations that achieve both high resolution and high accuracy. Two benchmark problems, modelling a single crack and a random porous medium, are used to demonstrate the robustness of the method and illustrate the capabilities of the adaptive refinement technique in resolving the saturation field and the complex interaction (transport phenomena) between two fluids in heterogeneous media. © 2010 Elsevier Ltd.
DEFF Research Database (Denmark)
Paradelo Pérez, Marcos; Soto-Gómez, Diego; Pérez-Rodrígez, Paula;
2014-01-01
be included in modeling non-point source pollution by pesticides. We propose a simplified approach that uses a phase transition equation coupled to the diffusion equation that describes the release rate of AIs from commercial CRFs in porous media; the parameters are as follows: a release coefficient......, the solubility of the AI, and diffusion transport with decay. The model gives acceptable predictions of the pesticides release from commercial CRFs in diffusion cells filled with quartz sand. This approach can be used to study the dynamics of the CRF-porous media interaction. It also could be implemented in fate...... of agricultural chemical models to include the effect of CRFs....
Mesoscopic modeling of multi-physicochemical transport phenomena in porous media
Energy Technology Data Exchange (ETDEWEB)
Kang, Qinjin [Los Alamos National Laboratory; Wang, Moran [Los Alamos National Laboratory; Mukherjee, Partha P [Los Alamos National Laboratory; Lichtner, Peter C [Los Alamos National Laboratory
2009-01-01
We present our recent progress on mesoscopic modeling of multi-physicochemical transport phenomena in porous media based on the lattice Boltzmann method. Simulation examples include injection of CO{sub 2} saturated brine into a limestone rock, two-phase behavior and flooding phenomena in polymer electrolyte fuel cells, and electroosmosis in homogeneously charged porous media. It is shown that the lattice Boltzmann method can account for multiple, coupled physicochemical processes in these systems and can shed some light on the underlying physics occuning at the fundamental scale. Therefore, it can be a potential powerful numerical tool to analyze multi-physicochemical processes in various energy, earth, and environmental systems.
A finite volume method for density driven flows in porous media
Directory of Open Access Journals (Sweden)
Hilhorst Danielle
2013-01-01
Full Text Available In this paper, we apply a semi-implicit finite volume method for the numerical simulation of density driven flows in porous media; this amounts to solving a nonlinear convection-diffusion parabolic equation for the concentration coupled with an elliptic equation for the pressure. We compute the solutions for two specific problems: a problem involving a rotating interface between salt and fresh water and the classical but difficult Henry’s problem. All solutions are compared to results obtained by running FEflow, a commercial software package for the simulation of groundwater flow, mass and heat transfer in porous media.
Unifying diffusion and seepage for nonlinear gas transport in multiscale porous media
Song, Hongqing; Wang, Yuhe; Wang, Jiulong; Li, Zhengyi
2016-09-01
We unify the diffusion and seepage process for nonlinear gas transport in multiscale porous media via a proposed new general transport equation. A coherent theoretical derivation indicates the wall-molecule and molecule-molecule collisions drive the Knudsen and collective diffusive fluxes, and constitute the system pressure across the porous media. A new terminology, nominal diffusion coefficient can summarize Knudsen and collective diffusion coefficients. Physical and numerical experiments show the support of the new formulation and provide approaches to obtain the diffusion coefficient and permeability simultaneously. This work has important implication for natural gas extraction and greenhouse gases sequestration in geological formations.
A Fractal Model for the Transverse Thermal Dispersion Conductivity in Porous Media
Institute of Scientific and Technical Information of China (English)
郁伯铭; 李建华
2004-01-01
A quasi-analytical model, i.e. the fractal model, for the transverse thermal dispersion conductivity in porous media is presented based on the fractal characteristics of tortuous flow paths/streamlines in porous media. The fractal dimension of tortuous flow paths, the spatial deviation velocity and the transverse thermal dispersion conductivity are derived. The proposed model is expressed as functions of the fractal dimension of tortuous flow paths/streamlines, Peclet number, porosity and structural parameters. The present results are compared with those from the existing correlation, and good agreement is found between the present model predictions and those from the existing correlation.
Effect of water content on dispersion of transferred solute in unsaturated porous media
International Nuclear Information System (INIS)
Estimating contaminant migration in the context of waste disposal and/or environmental remediation of polluted soils requires a complete understanding of the underlying transport processes. In unsaturated porous media, water content impacts directly on porous solute transfer. Depending on the spatial distribution of water content, the flow pathway is more complex than in water saturated media. Dispersivity is consequently dependent on water content. Non-reactive tracer experiments performed using unsaturated sand columns confirm the dependence of dispersivity with pore velocity; moreover, a power law relationship between dispersivity and water content is evidenced. (authors)
Mass transfer and precipitation of dispersed particles in inhomogeneous filtering porous media
International Nuclear Information System (INIS)
Calculational and theoretical technique which permits to describe stationary and nonstationary processes of mass transfer in porous media (filters) is suggested. The problem of two-phase mixture (liquid sodium and impurity) transfer in porous media is under consideration in the case when sodium contains finely dispersed micro- and nano-sized impurity. Distributions of deposits in the filters in dependence to filtration rate and degree of packing are presented. It is pointed out that density fluctuations of packing effects on filter restriction and efficiency. This effect is essential in the case of fine particles when diffusion precipitation becomes prevailing
Characterization of porous media structure by non linear NMR methods.
Capuani, S; Alesiani, M; Alessandri, F M; Maraviglia, B
2001-01-01
In this paper we discuss the possibility of modifying the multiple spin echoes existing theory, developed for a homogeneous system, to describe also an inhomogeneous system such as a porous medium. We report here the first experimental application of MSE methods to materials like travertine. The ratio A(2)/A(1) from water in travertine presents minima for characteristic values of the delay time tau, like what was previously observed in the trabecular bone. By a judicious choice of the delay time tau and of the G gradient strength, the MSE sequence can be made sensitive to a specific length-scale of the sample heterogeneity. Furthermore the MSE image shows a particular new contrast that makes the non linear NMR method very attractive for the assessment of variations of the porous structure in porous systems. PMID:11445306
Institute of Scientific and Technical Information of China (English)
PEI Zheng-lin; WANG Shang-xu
2005-01-01
The paper presents a staggered-grid any even-order accurate finite-difference scheme for two-dimensional (2D),three-component (3C), first-order stress-velocity elastic wave equation and its stability condition in the arbitrary tilt anisotropic media; and derives a perfectly matched absorbing layer (PML) boundary condition and its staggered-grid any even-order accurate difference scheme in the 2D arbitrary tilt anisotropic media. The results of numerical modeling indicate that the modeling precision is high, the calculation efficiency is satisfactory and the absorbing boundary condition is better. The wave-front shapes of elastic waves are complex in the anisotropic media, and the velocity of qP wave is not always faster than that of qS wave. The wave-front triplication of qS wave and its events in both reflected domain and propagated domain, which are not commonly hyperbola, is a common phenomenon. When the symmetry axis is tilted in the TI media, the phenomenon of S-wave splitting is clearly observed in the snaps of three components and synthetic seismograms, and the events of all kinds of waves are asymmetric.
Wacker, Josias B; Parashar, Virendra K; Gijs, Martin A M
2011-04-19
We report the microfluidic chip-based assembly of colloidal silanol-functionalized silica nanoparticles using monodisperse water-in-oil droplets as templates. The nanoparticles are linked via silica bridges, thereby forming superstructures that range from doublets to porous spherical or rod-like micro-objects. Adding magnetite nanoparticles to the colloid generates micro-objects that can be magnetically manipulated. We functionalized such magnetic porous assemblies with horseradish peroxidase and demonstrate the catalytic binding of fluorescent dye-labeled tyramide over the complete effective surface of the superstructure. Such nanoparticle assemblies permit easy manipulation and recovery after a heterogeneous catalytic process while providing a large surface similar to that of the individual nanoparticles. PMID:21417232
On the Process of Gas Liberation in Porous Media
DEFF Research Database (Denmark)
Zhelezny, Petr; Shapiro, Alexander; Vu, Duc Thuong;
2006-01-01
of the liberation process was developed based on the theory of differential depletion in the presence of a porous medium. The porous samples involved were low-permeable North Sea core plugs and artificial glass core. The results of the experiments indicate rather uniform gas production in different parts...... of the samples. The results of the calculations indicate noticeable, although not extreme, lowering of the bubble point pressure (0.12-0.18 MPa) and decreased production of gas, compared to the depletion carried out in a PVT cell....
Flow in Porous Media with Special Reference to Breakwater Structures
DEFF Research Database (Denmark)
Andersen, O. Holst
A literature study concerning porous flow is carried out. For the stationary case, the hydraulic radius theory, for which some justification can be given based on Navier-Stokes equations, appears to be adequate. Three different porous flow regimes are identified and the associated flow resistance...... coefficients are found from the literature. For the non-stationary flow case, existing expressions are discussed, and with the aim of decribing the inertia term a new analogy based on cylinders/spheres is presented. The predicted variation of the virtual mass coefficient with the porosity compares to a series...
Reconstruction of three-dimensional porous media using a single thin section.
Tahmasebi, Pejman; Sahimi, Muhammad
2012-06-01
The purpose of any reconstruction method is to generate realizations of two- or multiphase disordered media that honor limited data for them, with the hope that the realizations provide accurate predictions for those properties of the media for which there are no data available, or their measurement is difficult. An important example of such stochastic systems is porous media for which the reconstruction technique must accurately represent their morphology--the connectivity and geometry--as well as their flow and transport properties. Many of the current reconstruction methods are based on low-order statistical descriptors that fail to provide accurate information on the properties of heterogeneous porous media. On the other hand, due to the availability of high resolution two-dimensional (2D) images of thin sections of a porous medium, and at the same time, the high cost, computational difficulties, and even unavailability of complete 3D images, the problem of reconstructing porous media from 2D thin sections remains an outstanding unsolved problem. We present a method based on multiple-point statistics in which a single 2D thin section of a porous medium, represented by a digitized image, is used to reconstruct the 3D porous medium to which the thin section belongs. The method utilizes a 1D raster path for inspecting the digitized image, and combines it with a cross-correlation function, a grid splitting technique for deciding the resolution of the computational grid used in the reconstruction, and the Shannon entropy as a measure of the heterogeneity of the porous sample, in order to reconstruct the 3D medium. It also utilizes an adaptive technique for identifying the locations and optimal number of hard (quantitative) data points that one can use in the reconstruction process. The method is tested on high resolution images for Berea sandstone and a carbonate rock sample, and the results are compared with the data. To make the comparison quantitative, two sets
Nuclear magnetic resonance as a method of fluid mobility detection in porous media
Zhakov, Sergey; Loskutov, Valentin
2016-04-01
The nuclear magnetic resonance (NMR) method is widely used for studying the structure of porous media and processes taking place in such media. This method permits to determine porosity and pore-size distributions, which have direct practical application in various areas. The problem of porous media permeability determination is connected directly with extraction of hydrocarbons from pays and water from aquiferous layers. But it is impossible to measure directly amount of fluid past through the fixes cross section for determination of bed permeability. So various indirect approaches are used to find correlation of permeability value with porosity and pore size distribution which can be determined directly using NMR relaxometry. In contrast to porosity, permeability is dynamic characteristic of porous media so it may be measured correctly only in conditions of moving fluid. Natural porous medium has branched pore structure, so a chaotic component of fluid velocity will occur even for constant mean filtration fluid velocity. In the presence of magnetic field gradient this chaotic fluid velocity will produce additional spin dephasing and decrease of relaxation time [1]. Direct detecting of fluid movement in porous core samples through the Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence has been demonstrated and theoretical model and analysis was given. Experiments were made on a set of sandstone samples (Berea, Bentheimer, Castle Gate, Leopard) and with synthetic high-perm samples made of abrasive material. The experiments show that the NMR spin echo measurements permit to fix mean fluid velocity mm/sec. The experiments and the theoretical model show that for low fluid velocities the mean relaxation rate is proportional to fluid velocity . The results may serve as the basis for determination of mobility of liquids in porous media and permeability. 1. P.T.Callaghan. Principles of Nuclear Magnetic Resonance Microscopy. 1991, Oxford University Press.
Multiscale modeling of high contrast brinkman equations with applications to deformable porous media
Brown, Donald
2013-06-18
Simulating porous media flows has a wide range of applications. Often, these applications involve many scales and multi-physical processes. A useful tool in the analysis of such problems in that of homogenization as an averaged description is derived circumventing the need for complicated simulation of the fine scale features. In this work, we recall recent developments of homogenization techniques in the application of flows in deformable porous media. In addition, homogenization of media with high-contrast. In particular, we recall the main ideas of the homogenization of slowly varying Stokes flow and summarize the results of [4]. We also present the ideas for extending these techniques to high-contrast deformable media [3]. These ideas are connected by the modeling of multiscale fluid-structure interaction problems. © 2013 American Society of Civil Engineers.
Use of POD in control of flow through porous media
Van Doren, J.; Markovinovic, R.; Jansen, J.D.
2006-01-01
During the design of development concepts for the exploitation of oil and gas reservoirs, frequent use is made of numerical simulation of the flow of multi-phase fluids through porous rock. Recently, increased attention has been paid to systematic optimization of well positions and operating paramet
How methylhydroxyethylcellulose (MHEC) influences drying in porous media
Faiyas, A.P.A.; Erich, S.J.F.; Soestbergen, M. van; Huinink, H.P.; Adan, O.C.G.; Nijland, T.G.
2015-01-01
This article presents both an experimental as well as a theoretical study on the effect of MethylHy droxyEthylCellulose (MHEC) on drying in porous materials using Nuclear Magnetic Resonance Imaging (NMR). MHEC, a water soluble polymer, is normally added to glue mortars as a water retention agent in
Friction factor for isothermal and nonisothermal flow through porous media
Koh, J. C.; Dutton, J. L.; Benson, B. A.; Fortini, A.
1977-01-01
Measurements were performed to determine the pressure drops for gaseous flow through porous materials of different microstructures, porosities, and thickness under isothermal and nonisothermal conditions at various temperature levels. Results were satisfactorily correlated by a simple equation relating the friction factor to the Reynolds number and porosities.
Flow of foams in two-dimensional disordered porous media
Dollet, Benjamin; Geraud, Baudouin; Jones, Sian A.; Meheust, Yves; Cantat, Isabelle; Institut de Physique de Rennes Team; Geosciences Rennes Team
2015-11-01
Liquid foams are a yield stress fluid with elastic properties. When a foam flow is confined by solid walls, viscous dissipation arises from the contact zones between soap films and walls, giving very peculiar friction laws. In particular, foams potentially invade narrow pores much more efficiently than Newtonian fluids, which is of great importance for enhanced oil recovery. To quantify this effect, we study experimentally flows of foam in a model two-dimensional porous medium, consisting of an assembly of circular obstacles placed randomly in a Hele-Shaw cell, and use image analysis to quantify foam flow at the local scale. We show that bubbles split as they flow through the porous medium, by a mechanism of film pinching during contact with an obstacle, yielding two daughter bubbles per split bubble. We quantify the evolution of the bubble size distribution as a function of the distance along the porous medium, the splitting probability as a function of bubble size, and the probability distribution function of the daughter bubbles. We propose an evolution equation to model this splitting phenomenon and compare it successfully to the experiments, showing how at long distance, the porous medium itself dictates the size distribution of the foam.
Dispersive surface waves along partially saturated porous media
Chao, G.; Smeulders, D.M.J.; Van Dongen, M.E.H.
2006-01-01
Numerical results for the velocity and attenuation of surface wave modes in fully permeable liquid/partially saturated porous solid plane interfaces are reported in a broadband of frequencies (100 Hz–1 MHz). A modified Biot theory of poromechanics is implemented which takes into account the interact
Boundary Layer Flows in Porous Media with Lateral Mass Flux
DEFF Research Database (Denmark)
Nemati, H; H, Bararnia; Noori, F;
2015-01-01
Solutions for free convection boundary layers on a heated vertical plate with lateral mass flux embedded in a saturated porous medium are presented using the Homotopy Analysis Method and Shooting Numerical Method. Homotopy Analysis Method yields an analytic solution in the form of a rapidly...
Potential of Porous-Media Combustion Technology as Applied to Internal Combustion Engines
Directory of Open Access Journals (Sweden)
Miroslaw Weclas
2010-01-01
Full Text Available The paper summarizes the knowledge concerning porous media combustion techniques as applied in engines. One of most important reasons of this review is to introduce this still not well known technology to researchers doing with internal combustion engine processes, thermal engines, reactor thermodynamics, combustion, and material science. The paper gives an overview of possible applications of a highly porous open cell structures to in-cylinder processes. This application means utilization of unique features of porous media for supporting engine processes, especially fuel distribution in space, vaporization, mixing with air, heat recuperation, ignition and combustion. There are three ways for applying porous medium technology to engines: support of individual processes, support of homogeneous combustion process (catalytic and non-catalytic with temperature control, and utilization of the porous structure as a heat capacitor only. In the first type of application, the porous structure may be utilized for fuel vaporization and improved fuel distribution in space making the mixture more homogeneous in the combustion chamber. Extension of these processes to mixture formation and ignition inside a combustion reactor allows the realization of a homogeneous and a nearly zero emissions level combustion characterized by a homogeneous temperature field at reduced temperature level.
Ortiz, Aurélie U; Boutin, Anne; Fuchs, Alain H; Coudert, François-Xavier
2012-11-01
We performed ab initio calculations of the elastic constants of five flexible metal-organic frameworks (MOFs): MIL-53(Al), MIL-53(Ga), MIL-47, and the square and lozenge structures of DMOF-1. Tensorial analysis of the elastic constants reveals a highly anisotropic elastic behavior, some deformation directions exhibiting very low Young's modulus and shear modulus. This anisotropy can reach a 400:1 ratio between the most rigid and weakest directions, in stark contrast to the case of nonflexible MOFs such as MOF-5 and ZIF-8. In addition, we show that flexible MOFs can display extremely large negative linear compressibility. These results uncover the microscopic roots of stimuli-induced structural transitions in flexible MOFs, by linking the local elastic behavior of the material and its multistability. PMID:23215398
Institute of Scientific and Technical Information of China (English)
无
2008-01-01
A recursive algorithm is adopted for the computation of dyadic Green's functions in three-dimensional stratified uniaxial anisotropic media with arbitrary number of layers. Three linear equation groups for computing the coefficients of the Sommerfeld integrals are obtained according to the continuity condition of electric and magnetic fields across the interface between different layers, which are in correspondence with the TM wave produced by a vertical unit electric dipole and the TE or TM wave produced by a horizontal unit electric dipole, respectively. All the linear equation groups can be solved via the recursive algorithm. The dyadic Green's functions with source point and field point being in any layer can be conveniently obtained by merely changing the position of the elements within the source term of the linear equation groups. The problem of singularities occurring in the Sommerfeld integrals is efficiently solved by deforming the integration path in the complex plane. The expression of the dyadic Green's functions provided by this paper is terse in form and is easy to be programmed, and it does not overflow. Theoretical analysis and numerical examples show the accuracy and effectivity of the algorithm.
Full 3D dispersion curve solutions for guided waves in generally anisotropic media
Hernando Quintanilla, F.; Lowe, M. J. S.; Craster, R. V.
2016-02-01
Dispersion curves of guided waves provide valuable information about the physical and elastic properties of waves propagating within a given waveguide structure. Algorithms to accurately compute these curves are an essential tool for engineers working in non-destructive evaluation and for scientists studying wave phenomena. Dispersion curves are typically computed for low or zero attenuation and presented in two or three dimensional plots. The former do not always provide a clear and complete picture of the dispersion loci and the latter are very difficult to obtain when high values of attenuation are involved and arbitrary anisotropy is considered in single or multi-layered systems. As a consequence, drawing correct and reliable conclusions is a challenging task in the modern applications that often utilize multi-layered anisotropic viscoelastic materials. These challenges are overcome here by using a spectral collocation method (SCM) to robustly find dispersion curves in the most complicated cases of high attenuation and arbitrary anisotropy. Solutions are then plotted in three-dimensional frequency-complex wavenumber space, thus gaining much deeper insight into the nature of these problems. The cases studied range from classical examples, which validate this approach, to new ones involving materials up to the most general triclinic class for both flat and cylindrical geometry in multi-layered systems. The apparent crossing of modes within the same symmetry family in viscoelastic media is also explained and clarified by the results. Finally, the consequences of the centre of symmetry, present in every crystal class, on the solutions are discussed.
Lattice Boltzmann Method for Diffusion-Reaction-Transport Processes in Heterogeneous Porous Media
Institute of Scientific and Technical Information of China (English)
XU You-Sheng; ZHONG Yi-Jun; HUANG Guo-Xiang
2004-01-01
Based on the lattice Boltzmann method and general theory of fluids flowing in porous media, a numerical model is presented for the diffusion-reaction-transport (DRT) processes in porous media. As a test, we simulate a DRT process in a two-dimensional horizontal heterogeneous porous medium. The influence of gravitation in this case can be neglected, and the DRT process can be described by a strongly heterogeneous diagnostic test strip or a thin confined piece of soil with stochastically distributing property in horizontal directions. The results obtained for the relations between reduced fluid saturation S, concentration c1, and concentration c2 are shown by using the visualization computing technique. The computational efficiency and stability of the model are satisfactory.
Effects of gravity and inlet location on a two-phase countercurrent imbibition in porous media
El-Amin, M.F.
2012-01-01
We introduce a numerical investigation of the effect of gravity on the problem of two-phase countercurrent imbibition in porous media. We consider three cases of inlet location, namely, from, side, top, and bottom. A 2D rectangular domain is considered for numerical simulation. The results indicate that gravity has a significant effect depending on open-boundary location.
Nonequilibrium capillarity effects in two‐phase flow through porous media at different scales
Bottero, S.; Hassanizadeh, S.M.; Kleingeld, P.J.; Heimovaara, T.J.
2011-01-01
A series of primary drainage experiments was carried out in order to investigate nonequilibrium capillarity effects in two‐phase flow through porous media. Experiments were performed with tetrachloroethylene (PCE) and water as immiscible fluids in a sand column 21 cm long. Four drainage experiments
Nonequilibrium capillarity effects in two-phase flow through porous media at different scales
Bottero, S.; Hassanizadeh, S.M.; Kleingeld, P.J.; Heimovaara, T.J.
2011-01-01
A series of primary drainage experiments was carried out in order to investigate nonequilibrium capillarity effects in two-phase flow through porous media. Experiments were performed with tetrachloroethylene (PCE) and water as immiscible fluids in a sand column 21 cm long. Four drainage experiments
Effects of Gravity and Inlet Location on a Two-Phase Countercurrent Imbibition in Porous Media
Directory of Open Access Journals (Sweden)
M. F. El-Amin
2012-01-01
Full Text Available We introduce a numerical investigation of the effect of gravity on the problem of two-phase countercurrent imbibition in porous media. We consider three cases of inlet location, namely, from, side, top, and bottom. A 2D rectangular domain is considered for numerical simulation. The results indicate that gravity has a significant effect depending on open-boundary location.
The in situ microbial enhanced oil recovery in fractured porous media
Energy Technology Data Exchange (ETDEWEB)
Soudmand-asli, Alireza; Ayatollahi, S. Shahab; Zareie, Maryam [School of Chemical and Petroleum Engineering, Shiraz University, Shiraz (Iran); Mohabatkar, Hassan [Department of Biology, School of Sciences, Shiraz University, Shiraz (Iran); Shariatpanahi, S. Farzad [Department of Chemical Engineering, Faculty of Engineering, University of Tehran, Tehran (Iran)
2007-08-15
These experiments aim to investigate the microbial enhanced oil recovery (MEOR) technique in fractured porous media using etched-glass micromodels. Three identically patterned micromodels with different fracture angle orientation of inclined, vertical and horizontal with respect to the flow direction were utilized. A non-fractured model was also used to compare the efficiency of MEOR in fractured and non-fractured porous media. Two types of bacteria were employed: Bacillus subtilis (a biosurfactant-producing bacterium) and Leuconostoc mesenteroides (an exopolymer-producing bacterium). The results show that higher oil recovery efficiency can be achieved by using biosurfactant-producing bacterium in fractured porous media. Further investigation on the effect of the mentioned bacteria on oil viscosity, porous media permeability and wettability suggests that the plugging of matrix-fracture interfaces by an exopolymer is the main reason for the low performance of the exopolymer-producing bacterium. Oil viscosity reduction as well as the reduction of IFT was also found to be the reason for better microbial recovery efficiencies of biosurfactant-producing bacterium in the fractured models. (author)
ENHANCING THE STABILITY OF POROUS CATALYSTS WITH SUPERCRITICAL REACTION MEDIA. (R826034)
Adsorption/desorption and pore-transport are key parameters influencing the activity and product selectivity in porous catalysts. With conventional reaction media (gas or liquid phase), one of these parameters is generally favorable while the other is not. For instance, while ...
Fate and transport of viruses and colloids in saturated and unsaturated porous media
Torkzaban, S.
2007-01-01
The fundamental mechanisms involved in fate and transport of colloidal particles (viruses and latex microspheres) in saturated and unsaturated porous media were systematically examined. Two different bacteriophages were used as surrogate for pathogenic viruses to investigate the effects of various w
Carbon monoxide as a tracer of gas transport in snow and other natural porous media
Huwald, H.; Selker, J.S.; Tyler, S.W.; Calaf, M.; Van de Giesen, N.C.; Parlange, M.B.
2012-01-01
The movement of air in natural porous media is complex and challenging to measure. Yet gas transport has important implications, for instance, for the evolution of the seasonal snow cover and for water vapor transport in soil. A novel in situmulti-sensor measurement system providing high-resolution
Non-equilibrium Models for Two Phase Flow in Porous Media: the Occurence of Saturation Overshoots
Duijn, C.J. van; Hassanizadeh, S.M.; Pop, I.S.; Zegeling, P.A.
2013-01-01
Several experiments have evidenced the occurrence of saturation overshoots for flows in homogeneous porous media. Such phenomena are ruled out by standard mathematical models, which are based on equilibrium assumptions. In this presentation we discuss nonequilibrium models, in particular including d
General slip regime permeability model for gas flow through porous media
Zhou, Bo; Jiang, Peixue; Xu, Ruina; Ouyang, Xiaolong
2016-07-01
A theoretical effective gas permeability model was developed for rarefied gas flow in porous media, which holds over the entire slip regime with the permeability derived as a function of the Knudsen number. This general slip regime model (GSR model) is derived from the pore-scale Navier-Stokes equations subject to the first-order wall slip boundary condition using the volume-averaging method. The local closure problem for the volume-averaged equations is studied analytically and numerically using a periodic sphere array geometry. The GSR model includes a rational fraction function of the Knudsen number which leads to a limit effective permeability as the Knudsen number increases. The mechanism for this behavior is the viscous fluid inner friction caused by converging-diverging flow channels in porous media. A linearization of the GSR model leads to the Klinkenberg equation for slightly rarefied gas flows. Finite element simulations show that the Klinkenberg model overestimates the effective permeability by as much as 33% when a flow approaches the transition regime. The GSR model reduces to the unified permeability model [F. Civan, "Effective correlation of apparent gas permeability in tight porous media," Transp. Porous Media 82, 375 (2010)] for the flow in the slip regime and clarifies the physical significance of the empirical parameter b in the unified model.
Directory of Open Access Journals (Sweden)
Zhe Yin
2013-01-01
Full Text Available We study symmetric finite volume element approximations for two-dimensional parabolic integrodifferential equations, arising in modeling of nonlocal reactive flows in porous media. It is proved that symmetric finite volume element approximations are convergent with optimal order in L2-norm. Numerical example is presented to illustrate the accuracy of our method.
On the Stream Function-Vorticity Finite Element Formulation for Incompressible Flow in Porous Media
Directory of Open Access Journals (Sweden)
Abdellatif Agouzal
2014-01-01
Full Text Available Stream function-vorticity finite element formulation for incompressible flow in porous media is presented. The model consists of the heat equation, the equation for the concentration, and the equations of motion under the Darcy law. The existence of solution for the discrete problem is established. Optimal a priori error estimates are given.
Zhe Yin; Qiang Xu
2013-01-01
We study symmetric finite volume element approximations for two-dimensional parabolic integrodifferential equations, arising in modeling of nonlocal reactive flows in porous media. It is proved that symmetric finite volume element approximations are convergent with optimal order in L2-norm. Numerical example is presented to illustrate the accuracy of our method.
Transport and Retention of Colloids in Porous Media: Does Shape Really Matter?
The effect of particle shape on its transport and retention in porous media was evaluated by stretching carboxylate-modified fluorescent polystyrene spheres into rod shapes with aspect ratios of 2:1 and 4:1. Quartz crystal microbalance with dissipation experiments (QCM-D) were c...
Brull, Stéphane
2008-01-01
Consider a model of flow of two compressible or incompressible and immiscible phases in a three dimensional porous media. The existence of a weak solution is obtained for two compressible immiscible fluids when the porosity depends on the global pressure and on the space variable.
FID-SPI pulse sequence for quantitative MRI of fluids in porous media.
Marica, Florea; Goora, Frédéric G; Balcom, Bruce J
2014-03-01
MRI has great potential for providing quantitative, spatially resolved information about fluids imbibed in porous media. The pure phase encode SPRITE technique has proven to be a very general method for the generation of density images in porous media; however, low flip-angle RF pulses and broad filter widths, required by short encoding times, yield sub-optimal S/N images. A 1-D phase-encoding sequence for T2(∗) mapping, named FID-SPI, is presented and analyzed in terms of image quality and accuracy of fluid content distribution in porous media. Extension to 2-D and 3-D imaging was straightforward and images of heterogeneous samples are presented. The FID-SPI measurement results in a series of individual T2(∗) weighted images acquired following RF excitation and pulsed phase-encoding gradients. Key to the performance of the FID-SPI method is high quality control of the magnetic field gradient pulse to ensure each FID point has identical spatial encoding. FID-SPI is intended for a quantitative determination of the spatially resolved fluid content in heterogeneous porous media, having the ability to determine the T2(∗) decay for each image pixel. T2(∗) mapping aids in estimation of the local fluid content.
Particle enhanced foam flow in porous media near the critical micelle concentration
Thorat, R.R.
2016-01-01
This thesis was performed in the framework of ErasmusMundus EU-INDIA scholarship programme. The main goal is to elucidate particle enhanced foam flow (surfactant water and nitrogen gas) in porous media near the critical micelle concentration. The thesis is divided in four parts: in the first part th
Elliptic random-walk equation for suspension and tracer transport in porous media
DEFF Research Database (Denmark)
Shapiro, Alexander; Bedrikovetsky, P. G.
2008-01-01
We propose a new approach to transport of the suspensions and tracers in porous media. The approach is based on a modified version of the continuous time random walk (CTRW) theory. In the framework of this theory we derive an elliptic transport equation. The new equation contains the time...
Energy Technology Data Exchange (ETDEWEB)
Xiang, Aishuang [Princeton University, Chemical and Biological Engineering Department (United States); Yan, Weile [Texas Tech University, Civil and Environmental Engineering (United States); Koel, Bruce E., E-mail: bkoel@princeton.edu [Princeton University, Chemical and Biological Engineering Department (United States); Jaffe, Peter R., E-mail: jaffe@princeton.edu [Princeton University, Civil and Environmental Engineering Department (United States)
2013-07-15
Iron oxide and iron nanoparticles (NPs) have been used effectively for environmental remediation, but are limited in their applications by strong retention in groundwater-saturated porous media. For example, delivery of NPs to large groundwater reservoirs would require large numbers of injection wells. To address this problem, we have explored polymer coatings as a surface engineering strategy to enhance transport of oxide nanoparticles in porous media. We report here on our studies of 2-line ferrihydrite NPs and the influence of poly (acrylic acid) (PAA) polymer coatings on the colloidal stability and transport in natural sand-packed column tests simulating flow in groundwater-saturated porous media. Measurements were also made of zeta potential, hydrodynamic diameter, and polymer adsorption and desorption properties. The coated NPs have a diameter range of 30-500 nm. We found that NP transport was improved by PAA coating and that the transport properties could be tuned by adjusting the polymer concentration. Our results demonstrate that a high stability of oxide particles and improved transport can be achieved in groundwater-saturated porous media by introducing negatively charged polyelectrolytes and optimizing polymer concentrations.
Calibrating the Shan-Chen lattice Boltzmann model for immiscible displacement in porous media
DEFF Research Database (Denmark)
Christensen, Britt Stenhøj Baun; Schaap, M.G.; Wildenschild, D.;
2006-01-01
The lattice Boltzmann (LB) modeling technique is increasingly being applied in a variety of fields where computational fluid dynamics are investigated. In our field of interest, environmentally related flow processes in porous media, the use of the LB method is still not common. For the LB...
Analysis of physical mechanisms underlying density-dependent transport in porous media
Landman, A.J.
2005-01-01
In this thesis, the interaction between (large) density gradients and flow and transport in porous media is studied. Large gradients in the density of groundwater exist for example near deep salt rock formations, which are considered as possible long-term storage sites for radioactive waste. Further
A New Method for the Analysis of Relative Permeability in Porous Media
Institute of Scientific and Technical Information of China (English)
许友生; 吴锋民
2002-01-01
By combining three-dimensional digital microtomography techniques with the lattice Boltzmann method, a newmethodology is used to analyse the relative permeability of multiphase flow in porous media. The results indicate that the two coupling coefficients K12 and K21 have the same magnitude, therefore the Onsager reciprocity still holds. The results also agree well with the results of pipe flow numerical experiments.
Interactions between bacteria and solid surfaces in relation to bacterial transport in porous media.
Rijnaarts, H.H.M.
1994-01-01
Interactions between bacteria and solid surfaces strongly influence the behaviour of bacteria in natural and engineered ecosystems. Many biofilm reactors and terrestrial environments are porous media. The purpose of the research presented in this thesis is to gain a better insight into the basic mec
On the Coupling of Incompressible Stokes or Navier–Stokes and Darcy Flows Through Porous Media
Girault, V.
2012-11-03
In this chapter, we present the theoretical analysis of coupled incompressible Navier-Stokes (or Stokes) flows and Darcy flows with the Beavers-Joseph-Saffman interface condition. We discuss alternative interface and porous media models. We review some finite element methods used by several authors in this coupling and present numerical experiments.
Sainath, Kamalesh; Teixeira, Fernando L
2014-05-01
We discuss the application of complex-plane Gauss-Laguerre quadrature (CGLQ) to efficiently evaluate two-dimensional Fourier integrals arising as the solution to electromagnetic fields radiated by elementary dipole antennas embedded within planar-layered media exhibiting arbitrary material parameters. More specifically, we apply CGLQ to the long-standing problem of rapidly and efficiently evaluating the semi-infinite length "tails" of the Fourier integral path while simultaneously and robustly guaranteeing absolute, exponential convergence of the field solution despite diversity in the doubly anisotropic layer parameters, source type (i.e., electric or equivalent magnetic dipole), source orientation, observed field type (magnetic or electric), (nonzero) frequency, and (nonzero) source-observer separation geometry. The proposed algorithm exhibits robustness despite unique challenges arising for the fast evaluation of such two-dimensional integrals. Herein we develop the mathematical treatment to rigorously evaluate the tail integrals using CGLQ, as well as discuss and address the specific issues posed to the CGLQ method when anisotropic, layered media are present. To empirically demonstrate the CGLQ algorithm's computational efficiency, versatility, and accuracy, we perform a convergence analysis along with two case studies related to modeling of electromagnetic resistivity tools employed in geophysical prospection of layered, anisotropic Earth media and validating the ability of isoimpedance substrates to enhance the radiation performance of planar antennas placed in close proximity to metallic ground planes.
Numerical simulation of fluid particle transport through porous media
Najam, S
1999-01-01
The work presented in this report aims at the numerical simulation of fluid particle transport through porous medium. For this purpose various mathematical models and numerical schemes are studied. A mathematical model is derived based on Darcy's Law and continuity equation, it is discretized using finite difference schemes and Guass Seidal iterative procedure is used as a solver. For transient problems Crank Nicolson's method is used. Finally a software in Visual Basic 3.0 is developed that can simulate fluid transport through porous medium by promoting the user to specify the material and geometrical properties of the medium. The unknown pressure heads can be determined at various nodal points and the results are visualized by the colored grid display or by the surface plots.
Diffusive and thermodiffusive transfer of magnetic nanoparticles in porous media.
Sints, Viesturs; Blums, Elmars; Maiorov, Michail; Kronkalns, Gunars
2015-05-01
Experimental results on mass transfer within a thin porous layer saturated with ferrofluid are outlined in this paper. From the analysis of particle concentration distribution across the layer it is shown that both the mass diffusion and the Soret coefficients of nanoparticles are remarkably less than those measured in free fluid. The particle transport coefficient changes due to an external uniform magnetic field qualitatively well agree with the predictions of existing theoretical research. The magnetic field that is oriented transversely to the porous layer causes an increase in the diffusion coefficient and a decrease in the Soret coefficient whilst the longitudinal field causes a reduction of the mass diffusion and an intensification of the particle thermodiffusion. PMID:25957178
Visualization of gas flow and diffusion in porous media
Kaiser, Lana G.; Meersmann, Thomas; Logan, John W.; Pines, Alexander
2000-01-01
The transport of gases in porous materials is a crucial component of many important processes in science and technology. In the present work, we demonstrate how magnetic resonance microscopy with continuous flow laser-polarized noble gases makes it possible to “light up” and thereby visualize, with unprecedented sensitivity and resolution, the dynamics of gases in samples of silica aerogels and zeolite molecular sieve particles. The “polarization-weighted” images of ...
Transport properties of porous media from the microstructure
Energy Technology Data Exchange (ETDEWEB)
Torquato, S. [Princeton Univ., NJ (United States)
1995-12-31
The determination of the effective transport properties of a random porous medium remains a challenging area of research because the properties depend on the microstructure in a highly complex fashion. This paper reviews recent theoretical and experimental progress that we have made on various aspects of this problem. A unified approach is taken to characterize the microstructure and the seemingly disparate properties of the medium.
Pore-Scale Study of Miscible Displacements in Porous Media Using Lattice Boltzmann Method
Zhang, Ting; Shi, Baochang; Huang, Changsheng; Liang, Hong
2015-12-01
In the past few years, the miscible displacements in porous media were usually simulated by some semiempirical models based on the volume averaging at the representative elementary volume scale. To better understand the microscopic mechanism of the viscous fingering phenomenon in porous media for miscible fluids, in this paper the miscible displacements processes in porous media are studied using the lattice Boltzmann method (LBM) at the pore scale. First, the code of LBM is tested by simulating the displacement process of two miscible fluids with the same viscosity between two parallel plates which is the well-known Taylor-Aris dispersion problem, and comparing the results with the theoretical predictions. Then, the effects of the Péclet number Pe, the viscosity ratio M and the structure of the porous media on the displacement phenomenon are investigated, and the location and velocity of the finger tip, the displacement efficiency are also studied. In this paper, the displacement efficiency is calculated by 1-m, here the quantity m is defined as m=V_M/V_T, where V_M is the volume of more viscous fluids (the displaced fluid) left behind the finger tip, V_T is the total pore volume behind the finger tip. It can be found that the "interface" of two fluids will become clearer with the increasing of the Péclet number. As Pe and M are large enough, the viscous fingering phenomenon will occur, and in the front of the finger, "mushroom-like" pattern can be observed. Besides, with the increasing of Pe or M the quantity m will be increased too, i.e., the displacement efficiency will be decreased. While Pe (or M) is greater than a certain value, the growth rate of the quantity m will slow down. The same trend was observed for the miscible displacement in capillary tubes or Hele-Shaw cells. Besides, changing the structure of the porous media makes the finger pattern different. The present simulation results provide a good understanding of the microscopic mechanism of the
Interface effects on multiphase flows in porous media
Energy Technology Data Exchange (ETDEWEB)
Zhang, Duan Z [Los Alamos National Laboratory
2008-01-01
Most models for multiphase flows in a porous medium are based on the straightforward extension of Darcy's law, in which each fluid phase is driven by its own pressure gradient. The pressure difference between the phases is thought to be an effect of surface tension and is called capillary pressure. Independent of Darcy's law, for liquid imbibition processes in a porous material, diffusion models are sometime used. In this paper, an ensemble phase averaging technique for continuous multi phase flows is applied to derive averaged equations and to examine the validity of the commonly used models. The closure for the averaged equations is quite complicated for general multiphase flows in a porous material. For flows with a small ratio of the characteristic length of the phase interfaces to the macroscopic length, the closure relations can be simplified significantly by an approximation with a second order error in the length ratio. The approximation reveals the information of the length scale separation obscured during the ensemble averaging process, and leads to an equation system similar to Darcy's law, but with additional terms. Based on interactions on phase interfaces, relations among closure quantities are studied.
Optical Analyses of Flow in and Transformation of Deformable Porous Media
Kvalheim Eriksen, Fredrik; Toussaint, Renaud; Jørgen Måløy, Knut; Turkaya, Semih; Flekkøy, Eirik
2014-05-01
This study focuses on the characterization of fluid flow through transforming porous media and the simultaneous transformation of the porous media itself. The motivation is to investigate how fluid flow and deformation of the porous media influence each other, which are complex feedback processes. As a source of data, we have performed controlled experiments of air injection into deformable porous media samples created in the lab. The samples are transparent, horizontal and quasi 2-dimensional, enabling us to visually observe fluid flow through a slice of deformable porous media. The experiments are recorded from above with a digital high-speed camera, providing the raw-data as image sequences with high framerates (250 - 1000 images/s). Analyses on the fluid flow are based on the spatial properties of the observed flow patterns. The spatial properties are derived digitally after the raw-images are transformed into binary images of the flow patterns. Analyses on the transformation of the porous media are based on the frame-to-frame displacement fields of the particles. Such displacement fields are obtained by evaluating a sequence of raw images with a Particle Image Velocimetry software. We aim to show connections between flow observations and porous media observations. Two different kinds of experiments are analyzed. The first is two-phase flow in deformable porous media, and the other is aerofracturing in dry, fine-grained granular packings. The samples for the two-phase flow experiments are created in a circular Hele-Shaw cell with the inlet in the center and the outlet along its rim. Inside the cell, glass beads form a monolayer of deformable porous media saturated with a viscous glycerol-water solution. During an experiment, air is injected into the center of the sample with a constant overpressure, which will force the air to drain the sample radially outwards. This two-phase flow is an unstable event creating fingering patterns of air, while at the same time
Three-Dimensional Imaging and Quantification of Biomass and Biofilms in Porous Media
Energy Technology Data Exchange (ETDEWEB)
Dorthe Wildenschild
2012-10-10
A new method to resolve biofilms in three dimensions in porous media using high-resolution synchrotron-based x-ray computed microtomography (CMT) has been developed. Imaging biofilms in porous media without disturbing the natural spatial arrangement of the porous media and associated biofilm has been a challenging task, primarily because porous media generally precludes conventional imaging via optical microscopy; x-ray tomography offers a potential alternative. One challenge for using this method is that most conventional x-ray contrast agents are water-soluble and easily diffuse into biofilms. To overcome this problem, silver-coated microspheres were added to the fluid phase to create an x-ray contrast that does not diffuse into the biofilm mass. Using this approach, biofilm imaging in porous media was accomplished with sufficient contrast to differentiate between the biomass- and fluid-filled pore spaces. The method was validated by using a two-dimensional micro-model flow cell where both light microscopy and CMT imaging were used to im age the biofilm. The results of this work has been published in Water Resources Research (Iltis et al., 2010). Additional work needs to be done to optimize this imaging approach, specifically, we find that the quality of the images are highly dependent on the coverage of the biofilm with Ag particles, - which means that we may have issues in dead-end pore space and for very low density (fluffy) biofilms. What we can image for certain with this technique is the biofilm surface that is well-connected to flow paths and thus well-supplied with nutrients etc.
Lattice Boltzmann Simulation of Permeability and Tortuosity for Flow through Dense Porous Media
Directory of Open Access Journals (Sweden)
Ping Wang
2014-01-01
Full Text Available Discrete element method (DEM is used to produce dense and fixed porous media with rigid mono spheres. Lattice Boltzmann method (LBM is adopted to simulate the fluid flow in interval of dense spheres. To simulating the same physical problem, the permeability is obtained with different lattice number. We verify that the permeability is irrelevant to the body force and the media length along flow direction. The relationships between permeability, tortuosity and porosity, and sphere radius are researched, and the results are compared with those reported by other authors. The obtained results indicate that LBM is suited to fluid flow simulation of porous media due to its inherent theoretical advantages. The radius of sphere should have ten lattices at least and the media length along flow direction should be more than twenty radii. The force has no effect on the coefficient of permeability with the limitation of slow fluid flow. For mono spheres porous media sample, the relationship of permeability and porosity agrees well with the K-C equation, and the tortuosity decreases linearly with increasing porosity.
Time domain numerical modeling of wave propagation in 2D acoustic / porous media
Chiavassa, Guillaume
2011-01-01
Numerical methods are developed to simulate the wave propagation in 2D heterogeneous fluid / poroelastic media. Wave propagation is described by the usual acoustics equations (in the fluid medium) and by the low-frequency Biot's equations (in the porous medium). Interface conditions are introduced to model various hydraulic contacts between the two media: open pores, sealed pores, and imperfect pores. Well-possedness of the initial-boundary value problem is proven. Cartesian grid numerical methods previously developed in porous heterogeneous media are adapted to the present context: a fourth-order ADER scheme with Strang splitting for time-marching; a space-time mesh-refinement to capture the slow compressional wave predicted by Biot's theory; and an immersed interface method to discretize the interface conditions and to introduce a subcell resolution. Numerical experiments and comparisons with exact solutions are proposed for the three types of interface conditions, demonstrating the accuracy of the approach...
A Twophase Multirate-Mass Transfer Model for Flow and Transport in Porous Media
Dentz, M.; Tecklenburg, J.; Neuweiler, I.; Carrera, J.
2015-12-01
We present an upscaled non-local model for two-phase flow and transport in highly heterogeneous porous media. The media under consideration are characterized by sharp contrasts in the hydraulic properties typical for fractured porous media, for example. A two-scale expansion gives an upscaled flow and transport formulation that models multiratemass transfer between mobile (fracture) and immobile (matrix) medium portions. The evolution of saturation due to viscous dominated flow in the mobile domain and mass exchange with the immobile zones through capillary countercurrent flow. The medium heterogeneity is mapped onto the mass transfer parameters, which are encoded in a memory functionthat describes the non-local flux between mobile and immobile zones. The upscaled model is parameterized by the medium heterogeneity and the distribution of hydraulic parameters. Breakthrough of the displaced fluidshows characteristic heavy tails due to fluid retention in immobile zones.
Critique of Burnett-Frind dispersion tensor for axisymmetric porous media
Energy Technology Data Exchange (ETDEWEB)
Lichtner, Peter C [Los Alamos National Laboratory; Kelkar, Sharad [Los Alamos National Laboratory; Robinson, Bruce A [Los Alamos National Laboratory
2008-01-01
This technical note provides a critique of the Burnett and Frind (1987) dispersion tensor for porous media with axial symmetry based on a previous publication by the authors (Lichtner et aI., 2002). In this work a new approach is used based on unit eigenvectors which simplifies the analysis. It is demonstrated that the Burnett-Frind dispersion tensor, although acceptable for small values of the vertical velocity, produces the incorrect behavior for both longitudinal and transverse dispersivity as the flow velocity varies from parallel to perpendicular to the axis of symmetry. A new form of the dispersion tensor is derived for axially symmetric porous media involving four dispersivity coefficients corresponding to longitudinal and transverse dispersion in horizontal and vertical directions, defined as perpendicular and parallel to the axis of symmetry, respectively. This new dispersion tensor corrects two fundamental problems with the dispersion tensor proposed by Burnett and Frind (1987) for axial symmetric media.
Homogenization of complex flows in porous media and applications
International Nuclear Information System (INIS)
Our work is a contribution to the understanding of transport of solutes in a porous medium. It has applications in groundwater contaminant transport, CO2 sequestration, underground storage of nuclear waste, oil reservoir simulations. We derive expressions for the effective Taylor dispersion taking into account convection, diffusion, heterogeneous geometry of the porous medium and reaction phenomena. Microscopic phenomena at the pore scale are up-scaled to obtain effective behaviour at the observation scale. Method of two-scale convergence with drift from the theory of homogenization is employed as an up-scaling technique. In the first part of our work, we consider reactions of mass exchange type, adsorption/desorption, at the fluid-solid interface of the porous medium. Starting with coupled convection-diffusion equations for bulk and surface concentrations of a single solute, coupled via adsorption isotherms, at a microscopic scale we derive effective equations at the macroscopic scale. We consider the microscopic system with highly oscillating coefficients in a strong convection regime i.e., large Peclet regime. The presence of strong convection in the microscopic model leads to the induction of a large drift in the concentration profiles. Both linear and nonlinear adsorption isotherms are considered and the results are compared. In the second part of our work we generalize our results on single component flow to multicomponent flow in a linear setting. In the latter case, the effective parameters are obtained using Factorization principle and two-scale convergence with drift. The behaviour of effective parameters with respect to Peclet number and Damkohler number are numerically studied. Freefem++ is used to perform numerical tests in two dimensions. (author)
Flow visualization in heat-generating porous media
International Nuclear Information System (INIS)
The work reported is in support of the Sandia Post-Accident Heat Removal Program, in which simulated LMFBR beds will be subjected to in-pile heating in the ACPR (Annular Core Pulsed Reactor). Flow visualization experiments were performed to gain some insight into the flow patterns and temperature distributions in a fluid-saturated heat-generating porous medium. Although much of the information presented is of a qualitative nature, it is useful in the recognition of the controlling transport process and in the formulation of analytic and numerical models
A generalized lattice Boltzmann model for flow through tight porous media with Klinkenberg's effect
Chen, Li; Kang, Qinjun; Hyman, Jeffrey De'Haven; Viswanathan, Hari S; Tao, Wen-Quan
2014-01-01
Gas slippage occurs when the mean free path of the gas molecules is in the order of the characteristic pore size of a porous medium. This phenomenon leads to the Klinkenberg's effect where the measured permeability of a gas (apparent permeability) is higher than that of the liquid (intrinsic permeability). A generalized lattice Boltzmann model is proposed for flow through porous media that includes Klinkenberg's effect, which is based on the model of Guo et al. (Z.L. Guo et al., Phys.Rev.E 65, 046308 (2002)). The second-order Beskok and Karniadakis-Civan's correlation (A. Beskok and G. Karniadakis, Microscale Thermophysical Engineering 3, 43-47 (1999), F. Civan, Transp Porous Med 82, 375-384 (2010)) is adopted to calculate the apparent permeability based on intrinsic permeability and Knudsen number. Fluid flow between two parallel plates filled with porous media is simulated to validate model. Simulations performed in a heterogeneous porous medium with components of different porosity and permeability indicat...
Neutron imaging of hydrogen-rich fluids in geomaterials and engineered porous media: A review
Perfect, E.; Cheng, C.-L.; Kang, M.; Bilheux, H. Z.; Lamanna, J. M.; Gragg, M. J.; Wright, D. M.
2014-02-01
Recent advances in visualization technologies are providing new discoveries as well as answering old questions with respect to the phase structure and flow of hydrogen-rich fluids, such as water and oil, within porous media. Magnetic resonance and x-ray imaging are sometimes employed in this context, but are subject to significant limitations. In contrast, neutrons are ideally suited for imaging hydrogen-rich fluids in abiotic non-hydrogenous porous media because they are strongly attenuated by hydrogen and can "see" through the solid matrix in a non-destructive fashion. This review paper provides an overview of the general principles behind the use of neutrons to image hydrogen-rich fluids in both 2-dimensions (radiography) and 3-dimensions (tomography). Engineering standards for the neutron imaging method are examined. The main body of the paper consists of a comprehensive review of the diverse scientific literature on neutron imaging of static and dynamic experiments involving variably-saturated geomaterials (rocks and soils) and engineered porous media (bricks and ceramics, concrete, fuel cells, heat pipes, and porous glass). Finally some emerging areas that offer promising opportunities for future research are discussed.
Absorption of strain waves in porous media at seismic frequencies
Chelidze, T. L.; Spetzler, H. A.; Sobolev, G. A.
1996-06-01
An understanding of strain wave propagation in fluid containing porous rocks is important in reservoir geophysics and in the monitoring in underground water in the vicinity of nuclear and toxic waste sites, earthquake prediction, etc. Both experimental and theoretical research are far from providing a complete explanation of dissipation mechanisms, especially the observation of an unexpectedly strong dependence of attenuation Q -1 on the chemistry of the solid and liquid phase involved. Traditional theories of proelasticity do not take these effects into account. In this paper the bulk of existing experimental data and theoretical models is reviewed briefly in order to elecidate the effect of environmental factors on the attenuation of seismic waves. Low fluid concentrations are emphasized. Thermodynamical analysis shows that changes in surface energy caused by weak mechanical disturbances can explain observed values of attenuation in real rocks. Experimental dissipation isotherms are interpreted in terms of monolayered surface adsorption of liquid films as described by Langmuir's equation. In order to describe surface dissipation in consolidated rocks, a surface tension term is added to the pore pressure term in the O'Connell-Budiansky proelastic equation for effective moduli of porous and fractured rocks. Theoretical calculations by this modified model, using reasonable values for elastic parameters, surface energy, crack density and their geometry, lead to results which qualitatively agree with experimental data obtained at low fluid contents.
Models for seismic wave propagation in periodically layered porous media
Kudarova, A.; Van Dalen, K.N.; Drijkoningen, G.G.
2014-01-01
Several models are discussed for seismic wave propagation in periodically layered poroelastic media where layers represent mesoscopic-scale heterogeneities that are larger than the pore and grain sizes but smaller than the wavelength. The layers behave according to Biot’s theory. Wave propagation no
Thermal conductivity of granular porous media: A pore scale modeling approach
Directory of Open Access Journals (Sweden)
R. Askari
2015-09-01
Full Text Available Pore scale modeling method has been widely used in the petrophysical studies to estimate macroscopic properties (e.g. porosity, permeability, and electrical resistivity of porous media with respect to their micro structures. Although there is a sumptuous literature about the application of the method to study flow in porous media, there are fewer studies regarding its application to thermal conduction characterization, and the estimation of effective thermal conductivity, which is a salient parameter in many engineering surveys (e.g. geothermal resources and heavy oil recovery. By considering thermal contact resistance, we demonstrate the robustness of the method for predicting the effective thermal conductivity. According to our results obtained from Utah oil sand samples simulations, the simulation of thermal contact resistance is pivotal to grant reliable estimates of effective thermal conductivity. Our estimated effective thermal conductivities exhibit a better compatibility with the experimental data in companion with some famous experimental and analytical equations for the calculation of the effective thermal conductivity. In addition, we reconstruct a porous medium for an Alberta oil sand sample. By increasing roughness, we observe the effect of thermal contact resistance in the decrease of the effective thermal conductivity. However, the roughness effect becomes more noticeable when there is a higher thermal conductivity of solid to fluid ratio. Moreover, by considering the thermal resistance in porous media with different grains sizes, we find that the effective thermal conductivity augments with increased grain size. Our observation is in a reasonable accordance with experimental results. This demonstrates the usefulness of our modeling approach for further computational studies of heat transfer in porous media.
Friction factor correlation for CICC's based on a porous media analogy
Bottura, L; Lewandowska, M
2010-01-01
We use an analogy to porous media to derive a correlation for the friction factor in CICC s We start with a review of selected literature work on this topic We then recall the principles of the porous medium analogy and present the main body of our work on the analysis of pressure drop data We finally conclude with the proposed correlation The main novelty of our work is to propose predictive correlations for the permeability and drag factor that include the dependency on void fraction of the CICC s.
Bozorg, Ali; Gates, Ian D; Sen, Arindom
2015-02-01
Biofilm formation in natural and engineered porous systems can significantly impact hydrodynamics by reducing porosity and permeability. To better understand and characterize how biofilms influence hydrodynamic properties in porous systems, the genetically engineered bioluminescent bacterial strain Pseudomonas fluorescens HK44 was used to quantify microbial population characteristics and biofilm properties in a translucent porous medium. Power law relationships were found to exist between bacterial bioluminescence and cell density, fraction of void space occupied by biofilm (i.e. biofilm saturation), and hydraulic conductivity. The simultaneous evaluation of biofilm saturation and porous medium hydraulic conductivity in real time using a non-destructive approach enabled the construction of relative hydraulic conductivity curves. Such information can facilitate simulation studies related to biological activity in porous structures, and support the development of new models to describe the dynamic behavior of biofilm and fluid flow in porous media. The bioluminescence based approach described here will allow for improved understanding and control of industrially relevant processes such as biofiltration and bioremediation. PMID:25479429
Simplified Model for the Remobilization of Colloids and Nanoparticles in Porous Media
Gao, B.
2015-12-01
When entering the hydrological pathways, natural colloids and engineered nanoparticles may present potential risks to the environment, particularly the soil and groundwater systems. While soils can serve as filter media to immobilize the particles, flow perturbations, such as changes in solution chemistry and flow rate, may remobilize them. Most of the current models on the release of particles in porous media require solving coupled partial different equations that simulate both flow conditions and particle behaviors. This work will present a simple method to model the remobilization of colloids or nanoparticles in porous media. The simplified model assumes that the release of the immobilized particles in the porous media is only controlled by the wet front. It thus can be described by the advection-dispersion equation couple with simple kinetic expressions of particle release. Simulations from the simplified model were tested against experimental data of the remobilization of clay particles in sand column under transient flow conditions. The model results matched the experimental data very well.
FLUID FLOW SIMULATION IN RANDOM POROUS MEDIA AT PORE LEVEL USING THE LATTICE BOLTZMANN METHOD
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A. NABOVATI
2007-12-01
Full Text Available Fluid flow in two dimensional random porous media is simulated at pore level using the Lattice Boltzmann Method. Random media are constructed by placing identical rectangles with a random distribution and free overlapping. Different domain resolutions are examined and it is shown that the effect of the domain resolution is negligible in the range examined. Simulations clearly indicate, for the same porosity, the permeability of the random porous media is lower than the permeability of the regularly ordered medium; the permeability, independently of the porous media organization, varies exponentially with the porosity. Average tortuosity of the flow is calculated and it is proposed its correlation with the porosity. The effect of the aspect ratio of the randomly placed obstacles on the predicted tortuosity and permeability is studied, and it is found that an increase of the obstacles’ aspect ratio (height to width ratio yields an increase of the tortuosity and consequent decrease of the permeability. The predicted values of the permeability and tortuosity are in close agreement with the data available in the literature.
Instationary compaction wave propagation in highly porous cohesive granular media
Gunkelmann, Nina; Ringl, Christian; Urbassek, Herbert M.
2016-07-01
We study the collision of a highly porous granular aggregate of adhesive \\upmu m-sized silica grains with a hard wall using a granular discrete element method. A compaction wave runs through the granular sample building up an inhomogeneous density profile. The compaction is independent of the length of the aggregate, within the regime of lengths studied here. Also short pulses, as they might be exerted by a piston pushing the granular material, excite a compaction wave that runs through the entire material. The speed of the compaction wave is larger than the impact velocity but considerably smaller than the sound speed. The wave speed is related to the compaction rate at the colliding surface and the average slope of the linear density profile.
Algorithms for Solving Darcian Flow in Structured Porous Media
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Michal Kuráž
2013-01-01
Full Text Available This paper presents several algorithms that were implemented in DRUtES [1], a new open source project. DRUtES is a finite element solver for coupled nonlinear parabolic problems, namely the Richards equation with the dual porosity approach (modeling the flow of liquids in a porous medium. Mass balance consistency is crucial in any hydrological balance and contaminant transportation evaluations. An incorrect approximation of the mass term greatly depreciates the results that are obtained. An algorithm for automatic time step selection is presented, as the proper time step length is crucial for achieving accuracy of the Euler time integration method. Various problems arise with poor conditioning of the Richards equation: the computational domain is clustered into subregions separated by a wetting front, and the nonlinear constitutive functions cover a high range of values, while a very simple diagonal preconditioning method greatly improves the matrix properties. The results are presented here, together with an analysis.
Unexpected coupling between flow and adsorption in porous media.
Vanson, Jean-Mathieu; Coudert, François-Xavier; Rotenberg, Benjamin; Levesque, Maximilien; Tardivat, Caroline; Klotz, Michaela; Boutin, Anne
2015-08-14
We study the interplay between transport and adsorption in porous systems under a fluid flow, based on a lattice Boltzmann scheme extended to account for adsorption. We performed simulations on well-controlled geometries with slit and grooved pores, investigating the influence of adsorption and flow on dispersion coefficient and adsorbed density. In particular, we present a counterintuitive effect where fluid flow induces heterogeneity in the adsorbate, displacing the adsorption equilibrium towards downstream adsorption sites in grooves. We also present an improvement of the adsorption-extended lattice Boltzmann scheme by introducing the possibility for saturating Langmuir-like adsorption, while earlier work focused on linear adsorption phenomena. We then highlight the impact of this change in situations of high concentration of adsorbate. PMID:26139013
Mass transfer in porous media with heterogeneous chemical reaction
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Souza S.M.A.G.Ulson de
2003-01-01
Full Text Available In this paper, the modeling of the mass transfer process in packed-bed reactors is presented and takes into account dispersion in the main fluid phase, internal diffusion of the reactant in the pores of the catalyst, and surface reaction inside the catalyst. The method of volume averaging is applied to obtain the governing equation for use on a small scale. The local mass equilibrium is assumed for obtaining the one-equation model for use on a large scale. The closure problems are developed subject to the length-scale constraints and the model of a spatially periodic porous medium. The expressions for effective diffusivity, hydrodynamic dispersion, total dispersion and the Darcy's law permeability tensors are presented. Solution of the set of final equations permits the variations of velocity and concentration of the chemical species along the packed-bed reactors to be obtained.
Pressure drop of He II flow through a porous media
Maddocks, J. R.; van Sciver, S. W.
The paper reports on measurements of He II pressure drop across two porous SiO2 ceramic filter materials. These materials vary only in porosity, having values of 0.94 and 0.96. The average fiber diameter in both cases is approximately 5 microns. The experiment consists of a glass tube containing a piece of this sponge in one end. The tube is rapidly displaced downward in a bath of helium and the liquid levels are allowed to equilibrate over time producing variable velocities up to 10 cm/sec. The results are compared with those previously obtained using fine mesh screens. Good qualitative agreement is observed for turbulent flow; however, the behavior in the laminar flow regime is not fully understood.
Saad, Bilal Mohammed
2014-06-28
We propose and analyze a combined finite volume-nonconforming finite element scheme on general meshes to simulate the two compressible phase flow in porous media. The diffusion term, which can be anisotropic and heterogeneous, is discretized by piecewise linear nonconforming triangular finite elements. The other terms are discretized by means of a cell-centered finite volume scheme on a dual mesh, where the dual volumes are constructed around the sides of the original mesh. The relative permeability of each phase is decentred according the sign of the velocity at the dual interface. This technique also ensures the validity of the discrete maximum principle for the saturation under a non restrictive shape regularity of the space mesh and the positiveness of all transmissibilities. Next, a priori estimates on the pressures and a function of the saturation that denote capillary terms are established. These stabilities results lead to some compactness arguments based on the use of the Kolmogorov compactness theorem, and allow us to derive the convergence of a subsequence of the sequence of approximate solutions to a weak solution of the continuous equations, provided the mesh size tends to zero. The proof is given for the complete system when the density of the each phase depends on its own pressure. © 2014 Springer-Verlag Berlin Heidelberg.
International Nuclear Information System (INIS)
Fractured porous media are characterized by the presence of fractures at several scales with heterogeneous properties implying areas highly permeable by comparison with the rock. Hydraulically, these media are characterized by short reaction times, due to the fractures, and long reaction times, due to the rock. These media are important for several topics as contaminated sites, element storage and resources exploitation. The main challenge of fracture porous media modeling is the representation of the geometrical and physical heterogeneities. As an exact representation of the medium is not possible, it is necessary to determine the key properties of the medium. This study aims at determining the impact of the geometrical and physical properties of the fractures and the matrix from the local to the global scales. A first part consists in creating methods to evaluate structure effects on the exchange between the fractures and the matrix and a second part consists in using these methods on several media. Finally, we describe a new discrete dual-porosity model taking into account the properties of the media characterizing its behavior. (author)
Multiscale characterization of porous media properties for hydrocarbon reservoir simulation
Neeman, Henry; Lao, Hio-Wai; Simpson, Dale; Papavassiliou, Dimitrios V.
2001-07-01
Fluid flow through porous materials is critical for understanding and predicting the behavior of systems as diverse in function and scale as hydrocarbon reservoirs, aquifers, filters, membrane separators and even catalytic converters. Recently, there have been calls to incorporate more physics in oil reservoir simulations, as well as to enhance computational capability through the use of High Performance Computing (HPC), in order to improve reservoir management. Accurate prediction of reservoir behavior depends on the physical properties of not only the fluid but also the underlying rock formation. Contemporary approaches to solving these flows involve simulation of only a single physical scale. We are currently developing HiMuST (Hierarchical Multiscale Simulator Technology), an integrated multiscale simulation system for flow through heterogeneous porous materials. HiMuST uses a hierarchy of simulation codes to address the issue of rock property characterization at the pore scale and can self-adjust according to available input data. At the microscopic scale, HiMuST employs the Lattice Boltzmann Method, based on magnetic resonance digitizations of actual rock samples. At the mesoscopic scale, a stochastic model represents a pore network as a randomly generated skeleton of cylindrical pipes, based on physical characteristics determined by the microscopic simulation. We present computational and computer science issues involved in the HPC implementation of the codes and in integrating them into a seamless simulation system. Issues such as portability, scalability, efficiency and extensibility of the final product are also discussed, as well as the numerical methods implemented at each scale. Example simulation results are presented.
Permeability reduction by asphaltenes and resins deposition in porous media
Energy Technology Data Exchange (ETDEWEB)
R. Hamadou; M. Khodja; M. Kartout; A. Jada [Sonatrach/Division Centre de Recherche et Developpement, Boumerdes (Algeria)
2008-08-15
The deposition of crude oil polar fractions such as asphaltenes and resins in oil reservoir rocks reduce considerably the rock permeability and the oil production. In the present work, a crude oil and various core samples were extracted from Rhourd-Nouss (RN) reservoir rock. Afterwards, core flow experiments were carried out in the laboratory to investigate permeability reduction that causes formation damage. The core permeability damage was evaluated by flooding Soltrol, through the sample and measuring the solvent permeabilities, K{sub I} and K{sub f}, respectively, before and after injection of a given pore volume number of the crude oil. The data indicate that upon flooding the crude oil through the porous medium, considerable permeability reduction, expressed as the ratio (K{sub I} - K{sub f})/K{sub I}, and ranging from 72.4% to 98.3% were observed. The permeability reduction is found to result from irreversible retention of asphaltenes and resins in the porous core sample. However, no correlations could be established between the depth of the well, the core porosity, the core mineral compositions determined by X-ray analysis, and the permeability damage factors. In addition, effluents flowing away from RN wells were collected and analysed at various periods, after carrying out aromatic solvents squeezes. The amount of saturates, aromatics, resins, and asphaltenes (SARA analysis), of the crude oil, the deposited crude oil fraction, and the effluent's residues were measured and compared. The asphaltenes weight percent was found to increase from 1.56% for the crude oil to 11.42% for the deposited oil fraction, and was in the range 1.37-2.36% for the effluent's residues. Such results indicate that the deposited oil fraction and the effluent's residues consist mainly of asphaltenes and resins. 26 refs., 1 fig., 11 tabs.
Institute of Scientific and Technical Information of China (English)
LI Yuguo; LUO Ming; PEI Jianxin
2013-01-01
In this paper,we extend the scope of numerical simulations of marine controlled-source electromagnetic (CSEM) fields in a particular case of anisotropy (dipping anisotropy) to the general case of anisotropy by using an adaptive finite element approach.In comparison to a dipping anisotropy case,the first order spatial derivatives of the strike-parallel components arise in the partial differential equations for generally anisotropic media,which cause a non-symmetric linear system of equations for finite element modeling.The adaptive finite element method is employed to obtain numerical solutions on a sequence of refined unstructured triangular meshes,which allows for arbitrary model geometries including bathymetry and dipping layers.Numerical results of a 2D anisotropic model show both anisotropy strike and dipping angles have great influence on the marine CSEM responses.
Li, Fuping; Li, Jinshan; Kou, Hongchao; Huang, Tingting; Zhou, Lian
2015-09-01
Porous titanium and its alloys are believed to be promising materials for bone implant applications, since they can reduce the "stress shielding" effect by tailoring porosity and improve fixation of implant through bone ingrowth. In the present work, porous Ti6Al4V alloys for biomedical application were fabricated by diffusion bonding of alloy meshes. Compressive mechanical behavior and compatibility in the range of physiological strain rate were studied under quasi-static and dynamic conditions. The results show that porous Ti6Al4V alloys possess anisotropic structure with elongated pores in the out-of-plane direction. For porous Ti6Al4V alloys with 60-70 % porosity, more than 40 % pores are in the range of 200-500 μm which is the optimum pore size suited for bone ingrowth. Quasi-static Young's modulus and yield stress of porous Ti6Al4V alloys with 30-70 % relative density are in the range of 6-40 GPa and 100-500 MPa, respectively. Quasi-static compressive properties can be quantitatively tailored by porosity to match those of cortical bone. Strain rate sensitivity of porous Ti6Al4V alloys is related to porosity. Porous Ti6Al4V alloys with porosity higher than 50 % show enhanced strain rate sensitivity, which is originated from that of base materials and micro-inertia effect. Porous Ti6Al4V alloys with 60-70 % porosity show superior compressive mechanical compatibility in the range of physiological strain rate for cortical bone implant applications.
Magnetic Resonance Characterization of Porous Media Using Diffusion through Internal Magnetic Fields
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Eric E. Sigmund
2012-04-01
Full Text Available When a porous material is inserted into a uniform magnetic field, spatially varying fields typically arise inside the pore space due to susceptibility contrast between the solid matrix and the surrounding fluid. As a result, direct measurement of the field variation may provide a unique opportunity to characterize the pore geometry. The sensitivity of nuclear magnetic resonance (NMR to inhomogeneous field variations through their dephasing effects on diffusing spins is unique and powerful. Recent theoretical and experimental research sheds new light on how to utilize susceptibility-induced internal field gradients to quantitatively probe the microstructure of porous materials. This article reviews ongoing developments based on the stimulated echo-pulse sequence to extend the characterization of porous media using both spatially resolved and unresolved susceptibility-induced internal gradients that operate on a diffusing-spin ensemble.
Effects of an impermeable wall in dissipative dynamics of saturated porous media
Harris, Pietro Artale
2016-01-01
A phase transition model for porous media in consolidation is studied. The model is able to describe the phenomenon of fluid-segregation during the consolidation process, i.e., the coexistence of two phases di?ering from fluid content inside the porous medium under static load. Considering pure Darcy dissipation, the dynamics is described by a Cahn-Hilliard-like system of partial differential equations (PDE). The goal, here, is to study the dynamics of the formation of stationary fluid-rich bubbles. The evolution of the strain and fluid density pro?files of the porous medium is analyzed in two physical situation: fluid free to flow through the boundaries of the medium and fluid flow prevented at one of the two boundaries. Morover, an analytic result on the position of the interface between the two phases is provided.
Transport Phenomena in Porous Media Aspects of MicroMacro Behaviour
Ichikawa, Yasuaki
2012-01-01
This monograph presents an integrated perspective of the wide range of phenomena and processes applicable to the study of transport of species in porous materials. In order to formulate the entire range of porous media and their uses, this book gives the basics of continuum mechanics, thermodynamics, seepage and consolidation and diffusion, including multiscale homogenization methods. The particular structure of the book has been chosen because it is essential to be aware of the true properties of porous materials particularly in terms of nano, micro and macro mechanisms. This book is of pedagogical and practical importance to the fields covered by civil, environmental, nuclear and petroleum engineering and also in chemical physics and geophysics as it relates to radioactive waste disposal, geotechnical engineering, mining and petroleum engineering and chemical engineering.
Energy Technology Data Exchange (ETDEWEB)
Bru, A.; Casero, D. [CIEMAT, Madrid (Spain)
2001-07-01
We present a formal framework to describe tracer transport in heterogeneous media, such as porous media like bentonites. In these media, mean field approximation is not valid because there exist some geometrical constraints and the transport is anomalous. (Author)