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porous-medium
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Modeling of Hydraulic Fracturing in Fractured Saturated Porous Media Using the Extended Finite Element Method
, M.Sc. Thesis Sharif University of Technology ; Khoei, Amir Reza (Supervisor)
Abstract
In current study, we investigate crack propagation is saturated porous media by using the extended finite element method. The porous media is simulated by using well-known u-p formulation. In this regard the equilibrium equation of the bulk is employed together with momentum and mass balance equations of the fluid phase. The XFEM, known as one of the best methods in crack simulations, will be employed for numerical modelings. According to the method, crack propagation does not involve any changes in meshing, yet by using the concept of enrichment the elements are enabled to possess crack interfaces inside themselves. Thus by crack growth, only discritization alters and new DOFs are inserted...
Modeling of Hydraulic Fracture Propagation in Naturally Fractured Saturated Poruos Media Using the XFEM Method
, M.Sc. Thesis Sharif University of Technology ; Khoei, Amir Reza (Supervisor)
Abstract
Hydraulic fracture propagation occures in fractured saturated porous media due to fluid leakage from the crack faces and the consequent fluid pressure. In many cases, hydraulic fracturing may be considered as a detrimental phenomenon which endangers stability of human made structures like rock-fill dames. However, in recent decades the hydraulic fracturing has been an appealing method for increasing the production rate of low-permeability oil and gas reservoirs in petroleum industries.
In order to efficiently assess the behavior of saturated madia one needs to consider the coupling between the solid and fluid phases of the medium. To do so, the coupled formulation refered to as u-p...
In order to efficiently assess the behavior of saturated madia one needs to consider the coupling between the solid and fluid phases of the medium. To do so, the coupled formulation refered to as u-p...
Theoretical and Numerical Analysis of Shock Waves Propagation in Porous Medium
, Ph.D. Dissertation Sharif University of Technology ; Ahmadi, Mohammad Mehdi (Supervisor) ; Mohammadi, Soheil ($item.subfieldsMap.e)
Abstract
Particulate porous mateials have always been of interest in terms of reducing shock waves effects in different protective applications. Therefore, the physics governing the flow in porous media is especially significant for which different models have been presented by the researchers. The complexities of these media have caused many existing models to be unable to properly predict the behavior of granular media under shock loadings. On the other hand, the complexity of the equations makes the numerical solution of them cumbersome and costly in a way that many researchers do not solve the whole coupled equations and reduce their number. In addition, current high-resolution TVD solutions of...
Modeling Shear Band Propagation in Saturated Porous Media Using eXtended Finite Element Method
, M.Sc. Thesis Sharif University of Technology ; Kazemi, Mohammad Taghi (Supervisor)
Abstract
Shear band is more relevant in porous medias rather than continuum media. Shear band is a narrow region of solid experiencing intense shearing. After initiation of shear band, the sliding on two sides of the band occurs. The area inside the shear band undergoes extreme plastic deformation, while experiences elastic unloading outside of the band. In porous materials, the direction of slip and discontinuity in displacement field is not same, as a result of dilation. In fact dilation requires an increase in the volume of the shear band zone. The main difficulty in modeling the shear band is that the width of shear band in contrast to the dimension of the media, is too small. Consequently, the...
Multiscale Modeling of Microstructure Discontinuities in Saturated Porous Media Using XFEM
, M.Sc. Thesis Sharif University of Technology ; Khoei, Amir Reza (Supervisor)
Abstract
The main purpose of this study is computational modeling of saturated deformable porous media using multiscale finite element method and explicit modeling of discontinuities such as microcracks at the microscopic scale. The real engineering problems we deal with in the simulation of the phenomenas happening in nature or industrial applications, in contrast to the simplifications being assumed, occur in heterogeneous materials. Although most microscopic heterogeneities are not present in macroscopic scale, they do have their effects on material behavior. In the computational homogenization method, the problem is analyzed coupled in two scales, therefore, the macroscopic behavior of media is...
Numerical Modeling of Density-Driven Flow in Vuggy Porous Media Using Extended Finite Element Method
, M.Sc. Thesis Sharif University of Technology ; Khoei, Amir Reza (Supervisor)
Abstract
The main goal of this research is to investigate the effects of different types of heterogeneities on fluid flow and solute transport in saturated porous media. These heterogeneities are micro- and macro-fractures and cavities. For modeling micro- and macro-fractures we used an equivalent continuum model and extended finite element, respectively. Also, we modeled the problem by using mass conservation law for both components of the problem – fluid flow and the solute – and Darcy’s law. In modeling vuggy porous media, due to the high velocity of the fluid inside the free flow areas i.e. channels and cavities, we could not model the medium properly using Darcy’s law. Therefore, we had to use a...
Modeling of Crack Propagation in Non-isothermalsaturatedPorous Media using XFEM
,
M.Sc. Thesis
Sharif University of Technology
;
Khoei, Amir Reza
(Supervisor)
Abstract
The probability of crack appearance in soil structures and porous media is not avoidable, which could be the reason of structures collapse. According to the important affects, which they play in the vulnerability of the structures, they should be taking into account. The cracks have different effects on various materials. The most properties that cracks have, is their ability of conveying the fluid flow. For the most accurate analysis of discontinues domains, their governing equations should be taken and solved. Finite Element Method is one of the best solutions of differential governing equations. However, the appearance of some problems in the modeling of discontinues domain, was the...
Simulation of Two-Fluid Flow Through Particlulate Porous Media Contaning Moving Particles at Pore Scale Using Combined LB-DE Method
, Ph.D. Dissertation Sharif University of Technology ; Pak, Ali (Supervisor)
Abstract
A considerable number of engineering applications deal with flow of fluid(s) through particulate porous media. For certain engineering problems, fluid flow may displace and even dislodge the solid particles from the mass where a fluid-particle flow occurs. The complexity of involving processes which should be studied at the scale of moving particles transforms the analyses of these problems towards a difficult engineering task. Characteristics of solid grains such as size and shape and properties of the flowing fluid(s) such as viscosity and surface tension play essential roles in the behavior of fluid-particle systems. Also, when fluid flows through porous media, secondary processes such as...
Numerical Study of Induced-charge Electroosmotic (ICEO)Flow Effects on Mixing Phenomena in a Porous Media, Using Lattice Boltzmann Method
, M.Sc. Thesis Sharif University of Technology ; Taeibi Rahni, Mohammad (Supervisor) ; Salimi, Mohammad Reza (Co-Supervisor)
Abstract
Rapid preparation of a homogeneous mixture is essential for many chemical and biological applications, such as micro-scale biological-chemical agent detection, drug delivery, and DNA hybridization. Some mixing systems have a micro-scale geometry, which results in a very slow mixing process, mainly due to laminar flow in these systems. Mixing in a slow flow is performed only by molecular diffusion. In the absence of any disturbances, increased mixing is not possible simply by diffusion. Accordingly, a suitable and innovative method to improve mixing for such systems is required. Induced charge electro-osmosis is a new field of electro-osmotic flow, which performs better than conventional...
Modeling Saturated Porous Media Using Extended Finite Element Method
, M.Sc. Thesis Sharif University of Technology ; Khoei, Amir Reza (Supervisor)
Abstract
Soil structures have important roles in civil engineering applications. The most important types of these structures are soil dams and foundations which their damages may cause huge loss. Thus, appropriate analysis of these structures under possible loading conditions is unavoidable. The real behavior of this media can be achieved from the solution of its coupled governing differential equations. In order to solve this set of equations in practical applications, appropriate numerical solutions should be used. The finite element method can be called as one of the most important numerical solutions of differential equations which have been used in analyzing different types of engineering...
Hydraulic Crack Propagation in Heterogeneous Reservoir Based on Extended Multi-Scale Finite Element Method
, Ph.D. Dissertation Sharif University of Technology ; Khoei, Amir Reza (Supervisor)
Abstract
Many natural and engineering materials have a heterogeneous structure at a certain level of observation. These materials are often referred to as composite materials or multi-phase materials or heterogeneous materials. It has been widely recognized that many macroscopic phenomena originate from the mechanics of the microstructural constituents, such as inclusions, cracks, voids, etc. The size, shape, spatial distribution, volume fraction and properties of the microstructural constituents have a significant impact on the behavior of the material observed at the macroscale. The nature of hydrocarbon reservoirs as multi-phase porous media are known for heterogeneous media at various multiple...
Modeling of Cohesive Crack Propagation in Saturated and Semi Saturated Porous Media
, Ph.D. Dissertation Sharif University of Technology ; Khoei, Amir Reza (Supervisor) ; Mofid, Massoud (Supervisor)
Abstract
Modeling the water flow in cohesive fracture is a fundamental issue in the crack growth simulation of cracked concrete gravity dams and hydraulic fracture problems. Discontinuities in porous materials such as concrete, soil and rock have important role on the mechanical and hydraulic behavior of a multiphase system. The creation and propagation of discontinuities, such as cracks in a multi-physics system, lead to a complex non-linear coupled problem with continuous topological changes in the domain.In this study, a mathematical model is presented for for the analysis of dynamic fracture propagation in the saturated and semi-saturated porous media. The solid behavior incorporates a discrete...
XFEM Modeling of Dynamic Cohesive Crack Propagation in Saturated Porous Media
, M.Sc. Thesis Sharif University of Technology ; Khoei, Amir Reza (Supervisor)
Abstract
In this thesis, a fully coupled numerical model is developed for the modeling of dynamic cohesive crack propagation and hydraulic fracture in saturated porous media using extended finite element method. Many engineering structures like concrete or soil dams and buildings foundation are built with porous materials like concrete, rock and soil. Behavior of these materials in which void among the solid particles are filled with one or more fluids are so complicated rather than single solid phase. Dynamic analysis of porous mediums containing a discontinuity has many applications in various civil engineering fields including structure, earthquake, hydraulic structures, etc. For instance...
An optimal Liouville-Type Theorem for Radial Entire Solutions of the Porous Medium Equation with Source
,
M.Sc. Thesis
Sharif University of Technology
;
Hesaraki, Mahmoud
(Supervisor)
Abstract
In this thesis , we consider nonnegative (continuous) weak solutions of the porous medium equation with source , u_t-∆u^m=u^p, and p>m>1 .
Assume that, m>1 and 1< p/m u_t-∆u^m=u^p,xϵR^n ,tϵR
has no nontrivial, bounded radial solutions u≥0 .
In one space-dimensional, the conclusion of the result mentioned above remains true without the assumption of the radial symmetry. The proof is based on the intersection-comparison arguments , zero number argum- ents and a key step is to show the...
Assume that, m>1 and 1< p/m
has no nontrivial, bounded radial solutions u≥0 .
In one space-dimensional, the conclusion of the result mentioned above remains true without the assumption of the radial symmetry. The proof is based on the intersection-comparison arguments , zero number argum- ents and a key step is to show the...
The determination of effective diffusivity coefficients in a solvent gas heavy oil system for methane
, Article Petroleum Science and Technology ; Volume 30, Issue 24 , 2012 , Pages 2582-2593 ; 10916466 (ISSN) ; Dadvar, M ; Kharrat, R ; Ghazanfari, M. H ; Sharif University of Technology
2012
Abstract
In this investigation, an accurate high pressure and temperature diffusion setup was applied to measure the diffusion coefficients of methane in Iranian heavy oils in presence and absence of porous media by using the pressure-decay method. The solvent diffusivity in heavy oil was determined by both graphical and numerical methods. In addition, the effects of the porous medium and the temperature on the molecular diffusion coefficient of the solvent gas in the liquid phase were discussed and finally, using experimental data, a functionality dependence of molecular diffusivity on temperature and porous medium characteristics was proposed
Effect of distance-dependent dispersivity on density-driven flow in porous media
, Article Journal of Hydrology ; Volume 589 , October , 2020 ; Fahs, M ; Ataie Ashtiani, B ; Simmons, C. T ; Sharif University of Technology
Elsevier B.V
2020
Abstract
In this study, the effect of distance-dependent dispersion coefficients on density-driven flow is investigated. The linear asymptotic model, which assumes that dispersivities increase linearly with distance from the source of contamination and reach asymptotic values at a large asymptotic distance, is employed. An in-house numerical model is adapted to handle distance-dependent dispersion. The effect of asymptotic-dispersion on aquifer contamination is analyzed for two tests: (i) a seawater intrusion problem in a coastal aquifer and (ii) a leachate transport problem from a surface deposit site. Global Sensitivity Analysis (GSA) combined with the Polynomial Chaos Expansion (PCE) surrogate...
Analyzing transient heat and moisture transport surrounding a heat source in unsaturated porous media using the Green's function
, Article Geothermics ; Volume 81 , 2019 , Pages 224-234 ; 03756505 (ISSN) ; Ghasemi Fare, O ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
Generally, in most areas, groundwater level is deep and heat sources (e.g., energy piles)are embedded in unsaturated soil media. Therefore, in order to accurately analyze the soil response close to heat sources, both heat and moisture transport in unsaturated soil domain should be considered. Thermal loading changes the moisture content in the porous media. In this study, the energy conservation and mass fluid continuity equations derived from hydrothermal analysis of a partially saturated soil medium are considered in cylindrical coordinate system. To make the analytical solution possible, partial differential equations (PDEs)are turned into ordinary differential equations (ODEs), through...
A new insight into onset of inertial flow in porous media using network modeling with converging/diverging pores
, Article Computational Geosciences ; Volume 22, Issue 1 , February , 2018 , Pages 329-346 ; 14200597 (ISSN) ; Hassani, A. H ; Ghazanfari, M. H ; Sharif University of technology
Springer International Publishing
2018
Abstract
The network modeling approach is applied to provide a new insight into the onset of non-Darcy flow through porous media. The analytical solutions of one-dimensional Navier-Stokes equation in sinusoidal and conical converging/diverging throats are used to calculate the pressure drop/flow rate responses in the capillaries of the network. The analysis of flow in a single pore revealed that there are two different regions for the flow coefficient ratio as a function of the aspect ratio. It is found that the critical Reynolds number strongly depends on the pore geometrical properties including throat length, average aspect ratio, and average coordination number of the porous media, and an...
Modelling of power-law fluid flow through porous media using smoothed particle hydrodynamics
, Article Transport in Porous Media ; Volume 74, Issue 3 , 2008 , Pages 331-346 ; 01693913 (ISSN) ; Manzari, M. T ; Sharif University of Technology
2008
Abstract
The flow of non-Newtonian fluids through two-dimensional porous media is analyzed at the pore scale using the smoothed particle hydrodynamics (SPH) method. A fully explicit projection method is used to simulate incompressible flow. This study focuses on a shear-thinning power-law model (n < 1), though the method is sufficiently general to include other stress-shear rate relationships. The capabilities of the proposed method are demonstrated by analyzing a Poiseuille problem at low Reynolds numbers. Two test cases are also solved to evaluate validity of Darcy's law for power-law fluids and to investigate the effect of anisotropy at the pore scale. Results show that the proposed algorithm can...
Monitoring of microscopic behavior of nano-enhanced colloidal gas aphron in fractured and un-fractured non-uniform porous medium
, Article Journal of Petroleum Science and Engineering ; Volume 210 , 2022 ; 09204105 (ISSN) ; Ghazanfari, M. H ; Sharif University of Technology
Elsevier B.V
2022
Abstract
The present article aimed to examine the pore-scale examination of a fluid capability to block pores and fractures deduced by return permeability and the blocking ability of a novel lightweight Colloidal Gas Aphron Nano-Fluid (CGANF) in heterogeneous fractured/un-fractured porous medium. Silica (S) and fumed silica (FS) nanoparticles, Sodium Dodecyl Sulfate (SDS) anionic surfactant, and Xanthan Gum (XG) bio-polymer were employed for following up CGANF bubbles' movements in incongruous micro-models’ inclusive crack. The transparent nature of the glass micro-model provides an intuition into the lenticular behavior of CGANF bubbles in the heterogeneous porous media. Differential pressure...