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Energy and the wealth of nations : an introduction to biophysical economics
, Book ; Klitgaard, Kent
Springer International Publishing AG
2018
Synthesis and Characterization of Graphene-based Material and Investigation of its Adsorption Properties for Radioactive Waste
, Ph.D. Dissertation Sharif University of Technology ; Outokesh, Mohammad (Supervisor)
Abstract
Nuclear power is a prominent alternative of fossil fuels that can effectively solve global warming, acid rains and other consequences of air pollutions, caused by combustion. Despite such obvious advantage, this highly compact form of energy suffers from a big problem corresponding to its nuclear waste. Graphene oxide (GO), a lamellar material with wide range of surface functional groups such as epoxy (C-O-C), hydroxyl, and carboxyl offers large surface area as well as high sorption capacity for the metallic cations. This thesis study presents a supercritical, and co-precipitation synthesis of magnetite- graphene oxide (M-GO) in which Fe3O4 nanoparticles are simultaneously formed, surface...
Two-phase Flow Modeling of Drop Impact on Moving Surfaces, Using Multiphase Lattice Boltzmann Flux Solver
, Ph.D. Dissertation Sharif University of Technology ; Tayyebi Rahni, Mohammad (Supervisor)
Abstract
Various situations of drop impact on solid surfaces occur widely in natural phenomena and industrial applications, as well as involve in the development of some new technologies, such as, 3D printers, interfacial materials, microfluidics, and biotechnology. Therefore, the relevant investigations have been increasing considerably in the last two decades. Most of these studies are related to the simple case of vertical drop impact on horizontal stationary surfaces, while in most cases vertical/oblique drop impact on horizontal/inclined stationary/moving surfaces in the absence/presence of a crossflow and their various combinations occur. One of the most important situations is drop impact on...
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...
Computational Simulation of a 2D Sloshing Flow in a Rectangular Tank with Baffle, Using LBM
, M.Sc. Thesis Sharif University of Technology ; Tayyebi Rahni, Mohammad (Supervisor)
Abstract
In the this study, a numerical simulation of two-dimensional incompressible sloshing flow in a rectangular tank with baffle(s), using Lattice Boltzmann Method (LBM) is presented. Finite difference LBM and two-phase "Lee" model were used. The potential form of intermolecular forces is utilized to guarantee the stability of the numerical scheme and the discretization of the solution domain is performed by a two dimensional structured grid. Two different distribution functions are applied to obtain pressure, momentum, and composition of the particles. Furthermore, the Boltzmann transport equation is discretized, by using standard D2Q9 method. The "dropl" test case is simulated by the present...
Air Pollution Modeling, Using AERMOD Model Coupled with OpenFOAM Software
, M.Sc. Thesis Sharif University of Technology ; Tayyebi Rahni, Mohammad (Supervisor) ; Rashidi, Yousef (Supervisor)
Abstract
Over the course of past decade, air pollution has been placed among the top issues chocking capital Tehran. Stationary source of air pollution is among the most important, but, less treated facors. On the year, 2014, Tehran’s air quality company addressed a number of projects in this very field could gain further governmental supports. This announcement could be a sign, showing the importance of this research. These researches in fact, have the potentioal to increase the authority’s decision making abilities in critical situations. As the models prognosticates future with acceptble accuracy, it leads to highly efficient dicissions. The results could also be used in demographic studies as...
Numerical Simulation of Bubble Cluster Dynamics, Using Lattice Boltzmann Method
, Ph.D. Dissertation Sharif University of Technology ; Tayyebi Rahni, Mohammad (Supervisor) ; Massah, Hamid Reza (Co-Advisor)
Abstract
Bubble cluster has attracted the interests of many researches since the early twentieth century. Despite its easy generation and numerous occurrences, its study is extremely complex. Describing the dynamical behavior of bubble clusters is possible when quite a few simplifying assumptions are utilized. In other words, one can observe that with current approaches, the relevant theoretical researches are not very valuable. In this research, however, lattice Boltzmann method, a rather recent mesoscopic approach, was used to study the behavior of bubbles in a bubble cluster. Of course, this is only the beginning and there is a long way before getting close to experimental results. However, there...
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...
An Investigation on the Effects of Porous Media on Propagation of Aero-acoustic Waves, Using LBM
,
M.Sc. Thesis
Sharif University of Technology
;
Tayyebi Rahni, Mohammad
(Supervisor)
;
Massah, Hamid Reza
(Co-Advisor)
Abstract
With advances in technology, production and propagation of sound waves in the air has become very important. One of the main goals of study of these waves is controlling them. The environment plays the most important role in sound propagation. Therefore, the properties of the environment and their effects should be studied. One such concern studied widespread previously, is porosity and porous media effects on the properties of a fluid flow and sound waves through it. An important application of this study is sound proofing systems. In this project two-dimensional numerical simulation of aeroacoustic waves passing through a porous media is carried out, using Lattice Boltzmann Method. The aim...
Numerical Simulation of Two-dimensional Sonoluminescence Phenomenon, Using Front Tracking/Ghost Fluid Method
, M.Sc. Thesis Sharif University of Technology ; Tayyebi Rahni, Mohammad (Supervisor)
Abstract
Sonoluminescence is a unique phenomenon in physics, which is known as the process of converting sound into light. By applying sound to a volume of liquid, with a specific geometrical shape (such as sphere) and forming standing waves around an existing bubble, the bubble first expands to a maximum radius and then gets extremely small leading to its supersonic collapse. During the collapse, the resulting shock wave approches the center of the bubble, causing extreme increase in the pressure and temperature at the center of the bubble. This causes flashing of light during small time scales (pico-seconds). This phenomenon is used in many fields, such as treatment of cancer. Also, the energy...
Computational Simulation of Supersonic Flow in an Axisymmetric Mixed Compression Inlet
, M.Sc. Thesis Sharif University of Technology ; Tayyebi Rahni, Mohammad (Supervisor) ; Ebrahimi, Abbas (Supervisor)
Abstract
Inlet performance is an important field in aerodynamic design of aerial vehicle engines. This study has been focused on nummerical investigation of inlet performance. For this purpose, a density based finite volume CFD code has been developed to solve supersonic axisymmetric flow in a mixed compression inlet. A structured multi-block grid and an explicit time discritization of Reynolds averaged Navier-Stokes (RANS) equations have been used. Furthermore, both Roe’s approximated Riemann solver and advection upwind splitting method (AUSM) have been utilized for computing inviscid flux vectors. Also, the monotone upstream centered schemes for conservation laws (MUSCL) extrapolation with Van...
Computational Simulation of the Effect of Breathing Particle Mass and Breathing Frequency on a Human Respiratory System
, M.Sc. Thesis Sharif University of Technology ; Tayyebi Rahni, Mohammad (Supervisor)
Abstract
Our surrounding environment is full of particles with different sizes. These suspended particles enter our body through respiration process, which of course has some negative effects. Therefore, it is very important to comprehend the mechanisms and the effective parameters on these particles motion and their deposition inside the human airway. This work numerically investigates the effects of particles mass and breathing frequency on the deposition of particles in human respiratory system. To this end, a realistic 3-D model of human respiratory system geometry, including nostrils, vestibule, nasal cavity, human sinuses, nasopharynx, oropharynx, larynx, trachea, and main bronchus has been...
Numerical Investigation of Interaction Noise Using Rod-Airfoil Model
, M.Sc. Thesis Sharif University of Technology ; Farshchi, Mohammad (Supervisor) ; Tayyebi Rahni, Mohammad (Supervisor)
Abstract
In this thesis the interaction noise created by fluid flow with low Mach number over a rod-airfoil model simulated. Some numerical and experimental benchmark data for comparison and validation of results exist in articles. The simulation done by using Fluent 6.3 which restricts the choice of turbulence models to only 2D URANS. A study was undertaken on the cylinder as case study where some experimental aerodynamic and acoustic data are available. In this case study, the best turbulence model, discretization scheme and grid sizing were investigated. The only turbulence model which has the ability to simulate the near field and far field with a relatively good degree of accuracy was K-ω SST...
Optimization of Airfoil Design Using Low-dimensional POD Method
, M.Sc. Thesis Sharif University of Technology ; Tayyebi Rahni, Mohammad (Supervisor)
Abstract
The aim of this research was investigation, development and application of lowdimensional proper orthogonal decomposition method for simulation of flow field and airfoil design. Sine analytical methods have low accuracy and limitations and also experimental methods have other problems, researchers usually use computational approach, which mostly do not have acceptable efficiency and speeds of computational. The idea of application of reduced order modeling which originally comes from control theories and structural analysis, have attracted many researcher in recent years. In this research, we also used POD and flow data to obtain a fast module of aerodynamic airfoil design. The goals of...
Computational Simulation of Turbulent Endwall Effects in Gas Turbines, Using LES Approach
,
M.Sc. Thesis
Sharif University of Technology
;
Tayyebi Rahni, Mohammad
(Supervisor)
;
Ramezanizadeh, Mahdi
(Supervisor)
Abstract
The most common three-dimensional flows accuring in axial turbomachineries are endwall flows. These flows, which depend on inner hub and on external surface of airfoils are called secondary flows. In modern turbines, these flows reduce turbine efficiency up to about 3 percent.Many sientists are interested in investigation such flows. In this study, turbulent endwall flows are modeled using large eddy simulation approach. Also, SIMPLE algoritm and Smagorinsky subgrid scale model are used. Non-orthogonal curvilinear coordinate system and structural grid are implemented.To verify the results, they were compared with some existing experimental data which, showed that current numerical results...
Investigation of Flow over a Fin Located Downstream of a Supersonic Jet into Subsonic Crossflow
, Ph.D. Dissertation Sharif University of Technology ; Tayyebi Rahni, Mohammad (Supervisor) ; Soltani, Mohammad Reza (Co-Advisor)
Abstract
The problem of jet into a cross flow is one of the classic problems in fluid mechanics and has many engineering applications, such as in vector thrust control systems. Although many works have been done in this field, there have not been enough research in interactions of supersonic jets into compressible subsonic cross flows (specially its interaction with control surfaces downstream). Hence, the purpose of this research is to get better understanding of this interaction and its effects on control surfaces downstream (both numerical and experimental). Some of the individual achievements of this research are the design and manufacturing of supersonic jet system, parametric study of: boundary...
Simulation of Self-Propulsive Phenomenon, Using Lattice Boltzmann Method
, M.Sc. Thesis Sharif University of Technology ; Tayyebi Rahni, Mohammad (Supervisor) ; Taghizadeh Manzari, Mehrdad (Supervisor)
Abstract
Many human inventions are inspired by nature, such as fish swimming, bird/insect flight, etc. A basic consideration for the design of swimming machines is the design of propulsors. A creative design of propulsors can be inspired by fish locomotion. The term locomotion means that thrust is generated by undulation of fish body. Thus, there is no need to have an external propulsor. We need to understand how thrust is obtained by fish locomotion. In this study, sub-carangiform motion, which is a well known locomotion and which is practiced by most fish, is simulated numerically using Lattice Boltzmann method (LBM). To simulate the geometry of fishlike body, the profile of a flexible airfoil...
Low-dimensional POD Simulation of Unsteady Flow around Bodies with Arbitrary Shapes
, Ph.D. Dissertation Sharif University of Technology ; Tayyebi Rahni, Mohammad (Supervisor)
Abstract
The aim of this research was an investigation, development, and application of low- dimensional proper orthogonal decomposition (POD) method for simulation of unsteady flow around bodies. Since analytical methods have low accuracy and limitations and also experimental methods have other problems, researchers usually use computational approaches, which mostly do not have acceptable efficiency and speeds of computations (especially in 3-D unsteady flows). On the other hand, the idea of application of reduced order modelling, which orginally comes from control theories and structural analysis, have attracted many researchers in recent years. In this research, we also used POD for reduced order...
Numerical Analysis of a Supersonic Jet into a Subsonic Compressible Crossflow and the Effects on a Downstream Fin
, M.Sc. Thesis Sharif University of Technology ; Tayyebi Rahni, Mohammad (Supervisor)
Abstract
Jet into cross-flow interaction is one of the complex and fundamental problems in fluids dynamics and heat transfer, which is observed in various applications, such as pollutant discharges, film cooing of turbine blades, combustion chamber design of jet engines, trust vectoring systems, boundary layer control, and vertical short take-off and landing (VSTOL) aircrafts. One of the applications of this kind of flow is injection of supersonic jet into subsonic compressible cross-flow, which is used in trust vectoring systems of missiles. In this research, the two-dimensional interactions of supersonic jet into subsonic compressible cross-flow were investigated as two cases: "without a fin" and...