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Computer simulation of the effect of particle stiffness coefficient on the particle-fluid flows
, Article Particulate Science and Technology ; Volume 40, Issue 2 , 2022 , Pages 233-242 ; 02726351 (ISSN) ; Rajabi, M ; Sharif University of Technology
Taylor and Francis Ltd
2022
Abstract
The Computational fluid dynamics (CFD)–discrete element method (DEM) numerical simulation may be applied to predict the hydrodynamic behavior of dense particle–fluid flows. The main drawback of this simulation is the long computational time required owing to the large number of particles and the minute time-step required to maintain a stable solution. In this work, a new method to improve the efficiency and accuracy of CFD–DEM simulations is presented. The particle stiffness coefficient is used as a flexible parameter to improve the accuracy and efficiency of the model. The particle concentration distribution results are compared with experimental one’s to derive the optimum effective...
Modeling of heat transfer and fluid flow during gas tungsten arc welding of commercial pure aluminum
, Article International Journal of Advanced Manufacturing Technology ; Volume 38, Issue 3-4 , 2008 , Pages 258-267 ; 02683768 (ISSN) ; Serajzadeh, S ; Kokabi, A. H ; Sharif University of Technology
2008
Abstract
In the present study, the temperature and the velocity fields during gas tungsten arc welding of commercial pure aluminum were simulated using the solution of the equations of conversation of mass, energy and momentum in three dimensions and under steady-state heat transfer and fluid flow conditions. Then, by means of the prediction of temperature and velocity distributions, the weld pool geometry, weld thermal cycles and various solidification parameters were calculated. To verify the modeling results, welding experiments were conducted on two samples with different thicknesses and the geometry of the weld pool was measured. It is found that there is a good agreement between the predicted...
Prediction of solidification behaviour of weld pool through modelling of heat transfer and fluid flow during gas tungsten arc welding of commercial pure aluminium
, Article Materials Science and Technology ; Volume 24, Issue 12 , 2008 , Pages 1427-1432 ; 02670836 (ISSN) ; Serajzadeh, S ; Kokabi, A. H ; Sharif University of Technology
2008
Abstract
A mathematical model is developed to assess the solidification behaviour of the weld pools. To do so, during gas tungsten arc welding of commercial pure aluminium, equations of conversation of mass, energy and momentum are numerically solved considering three-dimensional steady state heat transfer and fluid flow conditions. The weld pool geometry, weld thermal cycles and various solidification parameters are calculated using temperature and velocity fields acquiring from the utilised model. The solidification behaviour of the weld pool at the weld centreline and the fusion line is then studied using the solidification parameters including temperature gradient G, solidification rate R and 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...
Modeling Aphron-Based Drillng Fluid Penetration Rate into the Reservoir Formation and Analyzing the Permeability Change Behavior
, M.Sc. Thesis Sharif University of Technology ; Jamshidi, Saeed (Supervisor)
Abstract
Aphron drilling fluids or CGA fluids are the wellknown updated drilling fluids in recent years.this kind of drilling fluids can control the mud loss into the formation and thus reduce formation damage and drilling costs. its structure consists of two phase fluid (gas and liquid) that the aphrons are the micro bubbles with 10 to 100 micrometer diameter that have strong stability in liquid phase compared to foamy drilling fluids. Generally aphron drilling fluids are made of base drilling fluid and surfactants, for more stability, mixed surfactant-polymer additive is so beneficial. in the last two decades, the Lattice-Boltazmann method is introduced for computational fluid dynamic area and...
The Simultaneous Effect of Nano Ferric Oxide and a Liquid Additive on Viscosity and Power Transmission of Drilling Cuttings to the Surface on the Water Base Mud Drilling to Optimization of These Properties
, M.Sc. Thesis Sharif University of Technology ; Goodarznia, Iraj (Supervisor) ; Ramazani, Ahmad (Co-Advisor)
Abstract
Transportation of cuttings and efficiency of the hole cleaning has been one of the major concerns of stake holders in the oil and gas industry.This is because a successful drilling program is a key to a productive and profitable oil and gas business. A successful drilling program is as a result of an efficiently cleaned hole. On the other hand, a poor or inefficient hole cleaning implies accumulation of cuttings or formation of cuttings bed in the well. This often leads to decreased rate of penetration, increased cost of drilling, fractured formation, increased plastic viscosity of mud as a result of grinding of cuttings and stuck pipe. Hole cleaning is effected primarily with a drilling...
Computational Simulation of Cooling of Porously Covered Surfaces, Using a Navier-stokes and Lattice Boltzmann Solver
, Ph.D. Dissertation Sharif University of Technology ; Tayyebi Rahni, Mohammad (Supervisor) ; Jam, Freydoon (Co-Advisor)
Abstract
Considering the wide range of applications of porous media for heat transfer enhancement in various components of industrial machineries, including solar collectors, air dryers, compact heat exchangers, electronic microchips, investigation of heat transfer characteristics in porous media has been a major concern for many researchers. On the other hand, precise understanding of the physics of porous media-flow interaction has been an open research topic for a long time. The present research however, has aimed at developing a computational method to simulate the interaction between fluid flow and porous media to investigate heat transfer from prously covered surfaces. Pore scale modeling of...
The Hydrodynamic Study of Swimming Microorganisms and Numerical Simulation of Micro-swimmers Using Computational Fluid Dynamics
, M.Sc. Thesis Sharif University of Technology ; Abasspour, Majid (Supervisor) ; Mahdigholi, Hamid (Supervisor)
Abstract
The design, optimization, and construction of systems that are capable of swimming in the low Reynolds conditions are urgently needed in the light of the recent human, medical, industrial and scientific needs. Therefore, it is necessary to inspire the movement of microorganisms to design and construct artificial micro swimmer as well as to achieve the best geometry for swimming. In order to achieve the optimum microstructure geometry, it is necessary to know the behavior and hydrodynamic interactions of the micro swimmer with the fluid and its outer channel. In this study, we numerically simulate the movement of a microorganism with a spiral tail in a circular channel using Computational...
Thermo-Hydro-Mechanical Modeling of Fractured Deformable Porous Media with Two-phase Fluid Flow using XFEM Technique
, M.Sc. Thesis Sharif University of Technology ; Khoei, Amir Reza (Supervisor)
Abstract
In this study, a fully coupled thermo-hydro-mechanical model for two-phase fluid flow and heat transport in fractured/fracturing porous media is introduced using the extended finite element method (XFEM) for numerical solution. The subject is important in the environmental and industrial fields such as hydraulic fracturing in petroleum industry, CO2 geo-sequestration, geothermal energy extraction and radioactive waste disposal in unsaturated porous media. In the fractured porous media, there are couplings of traction and heat and mass transfer between the fracture space and the surrounding media. Therefore, consideration of the fracture geometry explicitly in the modeling is important to...
Modeling of Two-Phase Fluid Flow in Fractured Reservoirs Using Extended Finite Element Method
, M.Sc. Thesis Sharif University of Technology ; Khoei, Amir Reza (Supervisor)
Abstract
A fully coupled numerical model is developed for the modeling of the cracks in porous media with flow of two fluids using the extended finite element method.The governing equations of two-phase fluid flow in deformable porous media, 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 formulation. The other variables are incorporated into the model via the experimentally determined functions that specify the relationship between the hydraulic properties of the porous medium, i.e....
Pore-scale Simulation of Flow around a Micro-porous Square Cylinder, Using Hybrid LBM-FVM, Considering Slip Condition Inside Porous Media
, M.Sc. Thesis Sharif University of Technology ; Tayyebi Rahni, Mohammad (Supervisor)
Abstract
In recent years, application of porous media is highlighted among researchers due to their wider use in micro-scale problems, such as in gas reservoirs, micro-filtering, and heat exchangers. In such applications, accurate description of flow behavior, using governing equations based on continuum assumption, is not valid, since mean free path has the same order as the characteristic length of the problem. In such cases, imposing appropriate slip condition on the fluid-solid interface of porous media (in pore-scale level), based on kinetics theory, is an appropriate approach. For this purpose, pore-scale simulation of flow inside porous media in slippery and transient regimes is carried out...
The Study of the Effect of Surfactant on the Liquid Drop Motion In Fluid
, M.Sc. Thesis Sharif University of Technology ; Firoozabadi, Bahar (Supervisor) ; Afshin, Hossein (Co-Supervisor)
Abstract
The drop motion in fluid and the mass transfer is one of the most interesting and favorite topics that has attracted the attention of many researchers. Knowing the functions of the factors affecting the deformation and the process of mass transfer and the effects of the addition of the surfactant, improve the efficiency of the related industrial processes.In this regard, the present study examines how the shape and speed of a moving Newtonian drop in a Newtonian fluid, the mass transfer of soluble material from inside the drop to the surrounding fluid and also the study of the effect of surfactant on the dynamics of moving droplet is studied numerically. During the drop movement, the...
Simulation of Blood Flow in Deformable Arteries using SPH
, M.Sc. Thesis Sharif University of Technology ; Taghizadeh Manzari, Mehrdad (Supervisor) ; Kazemzadeh Hannani, Siamak (Supervisor)
Abstract
Since coronary artery diseases are increasing every day, simulation of blood flow in blood vessels and their stenosis is one of the most important topics nowadays. Many efforts have been made to achieve numerical simulations using different methods such as Finite-Difference. In this thesis, an SPH method is used to simulate pulsatile blood flow in arteries. The weakly compressible algorithm consists of two steps of prediction and correction. In the prediction step, the velocity field is integrated forward in time without enforcing incompressibility. The correction step consists of enforcing incompressibility by solving the pressure Poisson equation which creates a trade-off between the...
Simulation of Blood Flow Subjected to Magnetic Field
, M.Sc. Thesis Sharif University of Technology ; Moosavi, Ali (Supervisor) ; Shafie, Mohammad Behshad (Supervisor)
Abstract
Considering the fact that there is a blood flow inside the vessels it is possible that blood flow is always associated with fouling and this may decrease the blood flow when a blood vessel is injured, the cells of your blood bond together to form a blood clot. The blood clot helps you stop bleeding. Blood clots are made of a combination of blood cells, platelets (small sticky cells that speed up the clot-making process), and fibrin (protein that forms a thread-like mesh to trap cells). Doctors call this kind of blood clot a “thrombus.” We study the effects of different parameters on the deposition of Nanoparticles on the surface of a bump in the blood vessels by the magnetic field. The...
Experimental Investigation of Formation Damage Caused by Wellbore Fluids Using Glass Micromodel
, M.Sc. Thesis Sharif University of Technology ; Mahani, Hassan (Supervisor)
Abstract
During all operations in oil and gas reservoirs, it is possible to cause formation damage. These damages can greatly reduce the rate of production. One of the major damages that can seriously affect the performance of a reservoir is the damage caused by drilling fluid. The main purpose of this thesis is to study the main mechanisms of formation damage caused by water-based drilling fluid using a glass micromodel for the first time. An accurate understanding of the mechanisms of formation damage can provide a good understanding of the selection of the type and concentration of materials used, as well as appropriate methods to control and eliminate damages. for controlling the drilling fluid...
Pore Scale Simulation of the Fluid/Fluid and Fluid/Rock Interactions on the Performance of Water Injection
, M.Sc. Thesis Sharif University of Technology ; Fatemi, Mobin (Supervisor) ; Pishvaie, Mahmood Reza (Co-Supervisor)
Abstract
Two-phase fluid flow physics in porous media is applied in various fields. Studies have shown that wettability and surface tension, which represent fluid-rock and fluid-fluid interactions, have a significant effect on the dynamics of the immiscible displacement. Although the effects of wettability and surface tension on the macroscopic behavior of fluid flow are known, there is less understanding of it at the micro scale. Considering the essential role of wettability and surface tension in various fields, this project seeks to investigate the effects of wettability and surface tension on the movement and distribution of fluids and the dominant displacement mechanisms within the porous media...
Investigation of Formation Damage and its Remediation Caused by Wellbore Fluids by Using Micromodel
, M.Sc. Thesis Sharif University of Technology ; Mahani, Hassan (Supervisor)
Abstract
Various methods have been developed to improve the production capacity of hydrocarbon wells, one of the most successful method is hydraulic fracture. This method, despite improving well production and increasing production levels in a reservoir, causes secondary damages such as water blockage, which is a result of the leakage of fracturing fluid into the fracture matrix and the deformation of the reservoir. This damage can reduce the production rate of a well. Studies prior to this study have mainly examined the damages caused by the leakage of fracturing fluids on a core scale. In most of these studies, damages has been studied only by measuring the pressure and changes in the permeability...
Design of a Microfluidic Digital Droplet PCR
, M.Sc. Thesis Sharif University of Technology ; Saeedi, Mohammad Saeed (Supervisor)
Abstract
Polymerase chain reaction, abbreviated as PCR, is a method of amplifying the number of copies of a desired DNA sequence through special protocols. The rapid advance of microfluidic devices and the emerging concept of digital microfluidics has resulted into the development of digital droplet PCR (ddPCR) systems with their significant uses in the detection of rare mutations, cancer diagnosis, and surveillance. A large number of micron-sized droplets are required to perform ddPCR. in this study, To investigate the gradient of confinements induced droplet self-breakup mechanism, we carried out the computational fluid dynamics (CFD) simulations for the two-phase flow using a commercial software...
Numerical Modeling of Carbon Dioxide Sequestration in Saline Aquifers with Considering the Hydrodynamic and Solubility Trapping
, M.Sc. Thesis Sharif University of Technology ; Khoei, Amir Reza (Supervisor)
Abstract
One of the most important factors in global warming is greenhouse gases such as carbon dioxide. Separating carbon dioxide from industrial activities such as fossil fuel power plants and storing it in the underground water can help combat the global warming challenge. In this research, numerical modeling of carbon dioxide sequestration in the aquifers under isothermal conditions is investigated. The process of storing carbon dioxide in aquifers consists of four main stages. In the first stage, the injected carbon dioxide accumulates into the aquifers under the impermeable bed. In the second stage, some carbon dioxide is trapped by the capillary forces inside the porous media's pores. In the...
Two-phase Fluids in Collision of Incompressible Inviscid Fluids Effluxing from Two Nozzles
, M.Sc. Thesis Sharif University of Technology ; Hesaraki, Mahmoud (Supervisor)
Abstract
This dissertation is devoted to the mathematical theory of two-dimensional injection of incompressible, irrota-tional, and inviscid fluids issuing from two infinitely long nozzles into a free stream.. In general, there is a free interface with constant jump of the Bernoulli constant on it, which is different and more difficult than the previous related works. Physically, it is called the collision fluid. The main result in this paper is that for given two co-axis symmetric infinitely long nozzles, imposing the incoming mass fluxes in the two nozzles, there is a unique piecewise smooth fluid collision function such that its free interface arises from the collision of fluids. It is a...