Sharif Digital Repository

This work presents an experimental study of the effect of a magnetic field on laminar forced convection of a ferrofluid flowing in a tube filled with permeable material. The walls of the tube are subjected to a uniform heat flux and the permeable bed consists of uniform spheres of 3-mm diameter. The ferrofluid synthesis is based on reacting iron (II) and iron (III) in an aqueous ammonia solution to form magnetite, Fe3O4. The magnetite is mixed with aqueous tetra methyl ammonium hydroxide, (CH3) 4NOH, solution. The dependency of the pressure drop on the volume fraction, and comparison of the pressure drop and the temperature distribution of the tube wall is studied. Also comparison of the... 

Concerning the geometrical effect of inner cylindrical hot pins, the natural convective heat transfer of nanofluid in a homogenous porous medium in a squared enclosure is numerically studied, using lattice Boltzmann method (LBM). In order to investigate the arrangement of inner cylinders for better heat transfer performance, five different configurations (including one, three, and four pins) were compared, while the total heat transfer area of inner pins were held fixed. Squared cavity walls and inner cylinder's surfaces were constantly held at cold and warm temperatures, respectively. In our simulation, Brinkman and Forchheimerextended Darcy models were utilized for isothermal... 

The present work numerically investigates the mass and heat transport flow of micropolar fluid in a channel having permeable walls. The appropriate boundary layer approximations are used to convert the system of flow model equations in ODEs, which are then numerically treated with the quasi-linearization method along with finite difference discretization. This technique creates an efficient way to solve the complex dynamical system of equations. A numerical data comparison is presented which assures the accuracy of our code. The outcomes of various problem parameters are portrayed via the graphs and tables. The concentration and temperature accelerate with the impacts of the Peclet numbers... 

The present work numerically investigates the mass and heat transport flow of micropolar fluid in a channel having permeable walls. The appropriate boundary layer approximations are used to convert the system of flow model equations in ODEs, which are then numerically treated with the quasi-linearization method along with finite difference discretization. This technique creates an efficient way to solve the complex dynamical system of equations. A numerical data comparison is presented which assures the accuracy of our code. The outcomes of various problem parameters are portrayed via the graphs and tables. The concentration and temperature accelerate with the impacts of the Peclet numbers... 

The present work numerically investigates the mass and heat transport flow of micropolar fluid in a channel having permeable walls. The appropriate boundary layer approximations are used to convert the system of flow model equations in ODEs, which are then numerically treated with the quasi-linearization method along with finite difference discretization. This technique creates an efficient way to solve the complex dynamical system of equations. A numerical data comparison is presented which assures the accuracy of our code. The outcomes of various problem parameters are portrayed via the graphs and tables. The concentration and temperature accelerate with the impacts of the Peclet numbers... 

The selective plugging effect of hydrophobic bacteria cell on secondary oil recovery performance was investigated. Water and aqua solution of purified Acinetobacter strain RAG-1 were injected into an oil-saturated heterogeneous micromodel porous media. Pure water injection expelled oil by 41%, while bacterial solution injection resulted in higher oil recovery efficiency (59%). In the simulation section, a smaller part of the heterogeneous geometry was applied as a computational domain. A numerical model was developed using coupled Cahn-Hilliard phase-field method and Navier-Stokes equations, solved by a finite element solver. In the non-plugging model, approximately 50% of the matrix oil was... 

In this paper, similarity solution of free convection from inclined permeable wall embedded in a stratified porous medium is investigated. It is assumed that the heated wall has constant temperature and permeability along the wall is variable. Energy equation and Darcy's law as momentum have been used. Due to similarity solution we consider only large wall inclination angle. Effects of mass flux, permeability variation function, and wall inclination angle on thermal and velocity boundary layer thickness and heat transfer at the wall are investigated. Copyright © 2005 by ASME  

Unidirectional experiments were carried out for the evaluation of the unsaturated permeability of the reinforcement during the injection and the saturated permeability. Saturated permeability was found to govern the permanent flow established after filling of the cavity. The unsaturated permeability was evaluated by a linear regression in function of the position of the resin front during transient flow experiments performed at constant injection pressure. The difference between these two permeability values is also related to the pore structure of the fiber bed  

In this work a series of solvent injection experiments was conducted on horizontal glass micromodels at several fixed flow rate conditions. The micromodels were initially saturated with heavy crude oil. The produced oil as a function of injected volume of solvents was measured using image analysis of the continuously provided pictures. In order to investigate the macroscopic behavior of the process in different media, several fractured, with constant width, and nonfractured five-spot micromodels were designed and used. The measured data have also been used for verifying and developing a simulation model that was later used for sensitivity analysis of some parameters that affect oil recovery.... 

Originally, application of nano zero valent iron (nZVI) particles for the removal of lead (Pb2+) in porous media was studied. At first, stabilized nZVI (S-nZVI) was prepared and characterized, then used in batch and continuous systems. Based on the batch experiments, corresponding reaction kinetics well fitted with the pseudo-first-order adsorption model, and reaction rate ranged from 0.01 to 0.04 g/mg/min depend on solution pH and the molar ratio between Fe and Pb. In batch tests, optimal condition with more than 90% removal efficiency at 60 min was observed at a pH range of 4 to 6 and Fe/Pb ratio more than 2.5. Continuous experiments exposed that Pb2+ remediation was as well influenced by... 

In this work, coupled Cahn–Hilliard phase field and Navier–Stokes equations were solved using finite element method to address the effects of micro-fracture and its characterizations on water-oil displacements in a heterogeneous porous medium. Sensitivity studies at a wide range of viscosity ratios (M) and capillary numbers (Ca), and the resultant log Ca–log M stability phase diagram, revealed that in both media, with/without fracture, the three regimes of viscous fingering, capillary fingering and stable displacement similarly occur. However, presence of the fracture caused water channeling phenomenon which resulted in reduction of the number of active fingers and hence the final oil... 

In this paper, a novel method which has been proposed during the last decade for increasing of the permeability of porous media of petroleum reservoirs by transferring of energy via ultrasound waves is investigated numerically. Increasing of permeability of porous media of petroleum reservoirs results in enhancing of oil recovery. This technique is based on the idea of transferring of energy to the liquid filled porous media via the ultrasound waves and consequently producing of pulsating vapor bubbles. The generated vapor bubbles transfer the energy of ultrasound waves in the liquid filled passages of a porous medium through velocity and pressure fields in the liquid domain and in turn... 

In this work a generalized non-equilibrium model of three-phase flow in porous media including gravity as well as capillary terms is developed and used for analysis of Riemann's problem in several three-phase systems. The proposed model uses the extension of Barenblatt model to three-phase systems considering dynamic effects in both relative permeability and capillary pressure functions. We compare the solution of the Riemann's problem when non-equilibrium effects are included. While equilibrium formulation develops unstable oscillatory solution in the elliptic region, non-equilibrium solution is smooth and stable. The results of this work might be helpful to better understanding the... 

In this article, transient two-dimensional mixed convection of nanofluids in the entrance region of a vertical channel has been studied carefully. The geometry under consideration consisted of a parallel-plate channel partly filled with a porous medium with a constant wall temperature. In the free flow region, the two-dimensional flow field has been governed by the Navier-Stokes equations. The general formulation of the momentum equations accounting for the inertial and the viscous effects in the presence of a porous medium has been used. Viscous dissipation effects have also been incorporated in the thermal energy equation. Effects of Brownian diffusion and thermophoresis have also been... 

Gravity, viscous, and capillary are three main forces affecting flow characteristics in porous media. No analytical solution can be found to model the flow by considering all these forces. In this work, by considering all these forces, the polymer-flooding process is modeled by using a numerical simulation approach. For characterizing the polymer, the modified Blake-Kozeny model is chosen, which benefits consideration of the permeability reduction due to polymer adsorption on the rock surface  

In this work a generalized non-equilibrium model of three-phase flow in porous media including gravity as well as capillary terms is developed and used for analysis of Riemann's problem in several three-phase systems. The proposed model uses the extension of Barenblatt model to three-phase systems considering dynamic effects in both relative permeability and capillary pressure functions. We compare the solution of the Riemann's problem when non-equilibrium effects are included. While equilibrium formulation develops unstable oscillatory solution in the elliptic region, non-equilibrium solution is smooth and stable. The results of this work might be helpful to better understanding the... 

In this work a series of hydrocarbon solvent injection experiments was performed on glass micromodels with different throat orientations that were initially saturated with crude oil at several fixed flow rate conditions. The solvent concentration as a function of location and time was measured using image analysis of color intensity of continuously provided pictures during the injection process. The provided concentration calibration curve of solvent in crude oil was used for back-calculating the solvent concentration along the dispersion zone. The longitude and transverse dispersion coefficients were determined by fitting the results of the mathematical model to the experimental data. It... 

Mechanical failure of materials adjacent to the production cavity and material disaggregation caused by fluid drag are considered as the most important parameters that affect sand production. In light of such factors, the coupling of two mechanisms-mechanical instability and hydrodynamic erosion-is indispensable in order to model this phenomenon successfully. This paper examines the applicability of a coupled hydro-mechanical erosion criterion for simulating sand production using the finite element method. The porous medium was considered fully saturated. The onset of sanding and production of sand were predicted by coupling mechanical failure and subsequent erosion of the grain particles...