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multiphase
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Implementing Appropriate Numerical Filters in the Lattice Boltzmann Method for Solving Multiphase Incompressible Flows with Large Density Ratio
, M.Sc. Thesis Sharif University of Technology ; Hejranfar, Kazem (Supervisor)
Abstract
In this study, two finite-difference lattice Boltzmann methods (FDLBM) are applied and assessed for the simulation of two-phase liquid-vapor flows with high density ratios. For this aim, the He-Shan-Doolen type lattice Boltzmann multiphase model is used and the spatial derivatives in the resulting system of equations are discretized by using the second-order central difference and modified Lax-Wendroff schemes. Suitable numerical dissipation terms and filters are applied to regularize the numerical solution and remove spurious waves generated by flow nonlinearities in smooth regions and at the same time to remove the numerical oscillations in the interface region of the two phases.Three...
Computational Two-dimensional Study of Oscillating Electrical Field on Break-up of a Drop, Using Hybrid Lattice Boltzmann-Finite Volume Method
, M.Sc. Thesis Sharif University of Technology ; Taeibi Rahni, Mohammad (Supervisor) ; Salimi, Mohammad Reza (Supervisor)
Abstract
Drop formation is an interesting field of research due to its wide-range of applications, such as drug delivery, biomedical studies, pharmaceutical industry, Lab-On-Chip (LOC) devices, etc. In recent years, researchers have used numerical studies to better understand how the process of forming and carefully examining the factors that affect quality improvement. One of the most effective methods in controlling the size and the process of drop formation is use of external force in microfluidic devices. Among the external force in this study, an electric field with oscillating current was used. Rapid methods for creating, deforming, and breaking up of drops in microfluidic applications are...
A Study on Two-Phase Flow in Bottom Hole Conditions in Horizontal Wells
, M.Sc. Thesis Sharif University of Technology ; Shad, Saeed (Supervisor)
Abstract
Considering the importance of oil and gas industries in Iran, issues related to drilling and exploitation of oil and gas fields are among the country's priorities and challenges in industries, research centers and universities, and extensive research is conducted in this field. Since during the process of oil production from oil wells and reservoirs, the formation of multiphase flows, including two-phase fluid flow, is inevitable, investigating the behavior of multiphase fluids, which is a branch of fluid mechanics, is of special importance. In this regard, in continuation of the research conducted in the Faculty of Chemical and Petroleum Engineering of Sharif University of Technology, in...
Theoretical and Experimental Study of the Influence of Chemical Environments and Investigation of their Effects on the Kinetics of Redox Reactions using Metal and Metal Oxide Nanocatalyst
, Ph.D. Dissertation Sharif University of Technology ; Gholami, Mohammad Reza (Supervisor)
Abstract
Bimetallic nanoparticles with unique structure, synergistic effect between two metals, and the tunable physical/chemical properties have been used for catalysis. Various methods exist for the staibility, and improvement of the catalytic performance of nanoparticles. In this thesis, different co-catalysts were applied to increase tha staibility, and activity of nanoparticles and metal oxides. In this way, Ni-based bimetallic nanoparticles including CuNi, CoNi, and AgNi, and AgPt with different concentrations were synthesized on the cerium oxide nanorods derived from cerium metal-organic frameworks and magnetic graphene oxide nanosheets, respectively and characterized. The catalytic...
Modeling of Dynamic Kill in Gas-Condensate Well
,
M.Sc. Thesis
Sharif University of Technology
;
Shad, Saeed
(Supervisor)
Abstract
By exploring huge gas-condensate reservoirs, three-phase transient flow modeling demonstrates its crucial role in designing dynamic kill, relief well parameters and kill procedure of such wells. Controlling gas-condensate well needs robust transient three phase models capable of capturing discontinuities in density, geometry and velocity of phases. In this paper, two phase Advection-Upstream-Splitting-Method hybrid scheme is extended to three-phase model capable of modeling blowout and dynamic kill in gas-condensate-water wells. Density and viscosity changes are calculated using Peng-Robinson equation of state and in according, flow model parameters are corrected.The capability of this model...
Multiscale Modelling of Non-Isothermal Multiphase Flow in Heterogeneous Porous Media with Computational Homogenization Approach
, Ph.D. Dissertation Sharif University of Technology ; Khoei, Amir Reza (Supervisor)
Abstract
In the real engineering problems, the existing materials in the nature or human-made materials, contain different heterogeneities from the view of small scale. Reinforced composite materials and porous media containing grains or micro-cracks are some examples of these materials. Due to the large amount of these heterogeneities as well as the small size, direct modelling of these micro-structures requires extremely high computational and memorial cost. Also, the equivalent models introduced in the literature, have strong limitations and therefore, cannot capture accurate behavior of the material. Hence, multiscale methods have been proposed in order to model these heterogeneous media with...
Modeling and Simulation of Vacuum Assisted Resin Transfer Molding Process with Flexible Tooling
, M.Sc. Thesis Sharif University of Technology ; Abedian, Ali (Supervisor)
Abstract
Resin Transfer Molding (RTM) which is one of the categories of Liquid Composite Molding (LCM) process, is considered as one of the most important process in polymer composite manufacturing. To improve this manufacturing method and reaching higher qualities, numerous modified methods has been developed. One of these modified methods is Vaccum Assisted Resin Trasnfer Molding with Flexible Tooling which is considerably applicable in manufacturing parts with high quality, large and complex geometry. Although, this manufacturing method has variety of advantages, there are some problems such as void formation making production difficult and dependent to experimental trial and error. So numerical...
Modeling and Simulation of Three-phase Tapered Fluidized Beds
, M.Sc. Thesis Sharif University of Technology ; Molaei Dehkordi, Asghar (Supervisor)
Abstract
Gas–liquid–solid fluidized beds are widely used in the petrochemical, biochemical, biotechnology, and wastewater treatment industries. These beds have the advantage of appropriate mass and heat transfer, better temperature control, and more solid content. In the present work, computational studies have been conducted on two-dimensional tapered fluidized beds to characterize their hydrodynamic behaviour. The presence of two dispersed phases in these beds results in difference in interphase interactions compared to two-phase fluidized beds. Generally, the three phase fluidized beds create a more complex flow pattern than the conventional type of fluidized beds. Three-phase flow in these beds...
Numerical Modeling of Liquid Jet Breakup Using SPH Method
, M.Sc. Thesis Sharif University of Technology ; Morad , Mohammad Reza (Supervisor) ; Omidvar, Pourya (Supervisor)
Abstract
Smoothed Particle Hydrodynamics (SPH) is a numerical Lagrangian meshless method which has numerous applications in astrophysics, hydrodynamics, free-surface flows, jets and sprays formation. Atomization of continuum liquid to fine droplets or in other words, liquid breakup processes are emerged in many engineering applications such as fuel sprays inside the combustion chamber of internal combustion engines that sizes of produced sprays significantly influence the engine’s efficiency. This research is accomplished to investigate the one-phase and two-phase flows of liquid jet breakup. For this aim, an open source code called SPHysics which solves the flow field by SPH method is utilized. This...
Dynamic Modeling of Cohesive Crack Propagation in Multiphase Porous Media Using the Extended Finite Element Method
, Ph.D. Dissertation Sharif University of Technology ; Khoei, Amir Reza (Supervisor)
Abstract
In this thesis, a fully coupled numerical model is developed for the modeling of the cohesive crack propagation and hydraulic fracturing in porous media using the extended finite element method in conjunction with the cohesive crack model. The governing equations, which account for the coupling between various physical phenomena, are derived within the framework of the generalized Biot theory. The solid phase displacement, the wetting phase pressure and the capillary pressure are taken as the primary variables of the three-phase formulation. The other variables are incorporated into the model via the experimentally determined functions that specify the relationship between the hydraulic...
Development of Optimal Integrated and Intensive Model of Energy Processing and Conversion
, Ph.D. Dissertation Sharif University of Technology ; Saboohi, Yadollah (Supervisor)
Abstract
In a single chemical plant, the operation of each unit operation is not independent of each other. In the other hand, the main operations are performed in reactors following by several separation steps including distillation and purification units. The total energy requirements are sullied by the heat exchanger networks. The performance of these systems is improved by integration and intensification of the reactor and distillation column in a single unit. The main objective of the present work is to provide an effective design approach to intensify the reactor and distillation column. In a reactive distillation column, the reaction and separation is done in a single unit. Increasing...
Design and Optimization of a Six-phase Winding-on-teeth Induction Machine for Electric Vehicle
, M.Sc. Thesis Sharif University of Technology ; Tahami, Farzad (Supervisor)
Abstract
Electrical machines represent an important research area in electrical engineering with numerous industrial applications. Multiphase induction machines are considered as the new generation of electrical machines in industrial applications because of their structure, robustness, simplicity, reasonable cost, long lifetime, and high reliability. A solution in the way of improving induction machine performances is using concentrated windings because they have many advantages such as short non-overlapping end turns, high fault-tolerant capabilities, and easy manufacturing. The main drawback of concentrated windings is its low-quality air gap flux density which significantly deteriorates induction...
Optimum Design Of Wave Mitigating Multi phase FGMs
, M.Sc. Thesis Sharif University of Technology ; Tvakkoli, Roohollah (Supervisor)
Abstract
Functionally graded materials (FGMs) are categorized in a branch of composite materials in which the local volume fraction of contributing phases are not fixed throughout the spatial domain, but vary gradually as a function of position. This spatial variation leads to the gradual variation of physical and mechanical properties inside the materials. It provides us the opportunity of designing multiple purpose materials by the variation of local volume fractions according to our goal. The optimal distribution of local volume fractions is a function of the spatial domain geometry and loading conditions, and in general situations, due to the complexity of the problem, it is not possible to...
Simulation of Flow Drag Reduction through Air Injection from the Porous Wall
, M.Sc. Thesis Sharif University of Technology ; Moosavi, Ali (Supervisor) ; Sadrhosseini, Hani (Supervisor)
Abstract
The effect of using backpressure of air injection in a microchannel on internal flow pressure drop were investigated in this study. Multiphase flows are commonly encountered in gas and oil industries. Flow fields in production operations are often complex and include multiphase flows of gas and liquid. Previously, because of their complex nature, these flow patterns have been mostly investigated only experimentally and empirical correlations based on the experimental data. From another point of view, it is almost impossible to experimentally realize all the flow conditions for each of the flow patterns. Nowadays computer facilities provide the tool to construct and use large-scale...
Numerical Simulation of A Vortex Cooled Combustion Chamber
,
M.Sc. Thesis
Sharif University of Technology
;
Farshchi, Mohammad
(Supervisor)
Abstract
The aim of the present research is to investigate the combustion chamber cooling with vortex method in presence of kerosene and liquid oxygen as propellants. For this purpose, a part of oxidizer is entered into the cylindrical combustion chamber tangentially (from bottem of the chamber), and creates a vortex flow (outer vortex). With motion of created outer vortex along the wall and eventually hit its top wall (the head of the chamber), secondary vortex (inner vortex) occurs along the center line, with a downward direction (opposite to the primary vortex). The fuel and other part of the oxidizer injection is also carried in the head of chamber, so by mixing the fuel and oxidizer that happens...
LBM Computational Simulation of Oscillations Caused by Formation and Detachment of Drops
, M.Sc. Thesis Sharif University of Technology ; Taeibi Rahni, Mohammad (Supervisor) ; Ebrahimi, Abbas (Supervisor)
Abstract
Formation and detachment of drops are of fundamental importance in studying two-phase flows, such as ink jet printing, emulsion, and spray. Drops are formed under the effects of surface tension forces. After formation, forces like gravity detach the drop from the rest of the fluid. The flow rate is varied from dripping to jetting regime. In this project, formation and detachment of drops were simulated, using LBM with phase field model, which can simulate flows with high-density ratios and is a robust method for applying wetting condition on the walls. Results were validated using single-phase and two-phase flows. After code validation, the oscillations caused by formation and detachment of...
Numerical Simulation of Cavitating Flows with Compressibility Effects
, M.Sc. Thesis Sharif University of Technology ; Hejranfar, Kazem (Supervisor)
Abstract
In this study, the numerical simulation of cavitating flows with compressibility effects is performed. The algorithm employs the multiphase Euler equations with homogeneous equilibrium model. The baseline differential equations system is similar to the one-phase system of equations and comprised of the mixture density, mixture momentums and mixture energy equations. Thephases considered for cavitating flows is liquid-vapor and liquid-gas fields. The system of governing equations is discretized using a cell-centered finite volume AUSM’s upwind scheme. The computations are presented for steady noncavitating/cavitating flows around 1D/2Dproblems for different conditions. A sensitivity study is...
Numerical Simulation of 2D Compressible Cavitation Flow Using Compact Finite-Difference Method
, M.Sc. Thesis Sharif University of Technology ; Hejranfar, Kazem (Supervisor)
Abstract
In the present study, the numerical simulation of 2D inviscid compressible cavitation flow is performed by using the compact finite-difference method. The problem formulation is based on the multiphase compressible Euler equations with the assumption of the homogeneous equilibrium model and the system of baseline differential equations is comprised of the continuity, momentum and energy equations for the vapor-liquid mixture. To complete the system of governing equations, the ideal gas relation is used for the vapor phase and the Tait relation is applied for the liquid phase, and therefore, the compressibility effects are considered for both the vapor and liquid phases. To analyze the flow...
Numerical Simulation of the Impact of a Drop with a Flat Surface in a Cross Flow, Using LBM
, M.Sc. Thesis Sharif University of Technology ; Taebi Rahni, Mohammad (Supervisor)
Abstract
In this research, numerical simulation of the impact of a drop on a flat surface with oblique velocity has been performed, using two-phase model of Lattice Boltzmann Method (conservative phase-field). During impact, it is important to investigate two-dimensional drop dynamics and to evaluate the effectiveness of the numerical method used. The model used here restores conservative phase field and preserves mass both locally and globally. In addition, to calculate the slope of the phase field, it calls the center points without engaging finite difference calculations. This makes it efficient for running parallel computations. A fixed dry and hard surface is considered and the drop impacts it...
Simulation of Flow in Anisotropic Heterogeneous Oil Reservoirs Using Compositional Model and Cell-Based Unstructured Grid
, Ph.D. Dissertation Sharif University of Technology ; Taghizadeh Manzari, Mehrdad (Supervisor)
Abstract
Reservoir simulation is a useful tool for efficient reservoir management and protective exploitation of non-renewable hydrocarbon resources as the main supplier of development programs in the country. Due to the nature of underground hydrocarbon reservoirs, the simulation faces several challenges, both in rock and fluid parts. These challenges should be overcome in order to provide reliable results from simulations. One of the major challenges pertaining to rock, is large discontinuous variations accompanied by anisotropy of rock permeability fields which causes numerous problems when governing equations are solved numerically. A viable numerical procedure shall account for complex reservoir...