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    Computational Simulation of a 2D Sloshing Flow in a Rectangular Tank with Baffle, Using LBM

    , M.Sc. Thesis Sharif University of Technology Goudarzi, Saman (Author) ; 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... 

    Computational Simulation of the Effect of Breathing Particle Mass and Breathing Frequency on a Human Respiratory System

    , M.Sc. Thesis Sharif University of Technology Goodarzi Ardakani, Vahid (Author) ; 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... 

    Seismic Behavior of Connections in Cold-Formed Steel Moment Frames

    , M.Sc. Thesis Sharif University of Technology Tayyebi, Kamran (Author) ; Kazemi, Mohammad Taghi (Supervisor)
    Abstract
    Today using cold-formed steel elements as members of light-weight structures is more common especially in low-rise residential and industrial buildings. Due to Thin-walled plates used to make these sections, members of the frame are prone to premature local buckling and they don’t show good ductility under seismic loadings. Beacause of these reasons, using cold-formed steel elements in moment frames has become a big challenge for scientists. Lots of numerical and experimental models have been presented.
    In this study, we investigated the behavior of a beam-column moment connection, consists of two back to back channel sections with curved flanges, using a plate passing through the... 

    Numerical Investigation of Interaction Noise Using Rod-Airfoil Model

    , M.Sc. Thesis Sharif University of Technology Hashemi Rabori, Zari (Author) ; 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... 

    Air Pollution Modeling, Using AERMOD Model Coupled with OpenFOAM Software

    , M.Sc. Thesis Sharif University of Technology Nazem, Amir (Author) ; 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... 

    Low-dimensional POD Simulation of Unsteady Flow around Bodies with Arbitrary Shapes

    , Ph.D. Dissertation Sharif University of Technology Moayyedi, Mohammad Kazem (Author) ; 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 Simulation of Two-dimensional Sonoluminescence Phenomenon, Using Front Tracking/Ghost Fluid Method

    , M.Sc. Thesis Sharif University of Technology Moezzi Rafie, Hamid (Author) ; 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... 

    Optimization of Airfoil Design Using Low-dimensional POD Method

    , M.Sc. Thesis Sharif University of Technology Marvi, Morteza (Author) ; 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... 

    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 Mohammadi, Masoud (Author) ; 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... 

    Comparison Of Seismic Risk Cost Of Multi-span Conc. & Steel Bridges By ET Method

    , M.Sc. Thesis Sharif University of Technology Alinezhad Tayyebi, Adel (Author) ; Esmaeil Purestekanchi, Homayoon (Supervisor)
    Abstract
    costs of construction of a structure include: initial construction cost, maintanance cost, seismic risk cost and etc., that in this investigation,the seismic risk of multi-span conc. & steel bridges has been compared. the seismic damage is converted to equivalent finincial value by the concept of life-cycle cost, and then is compared with initial construction cost of structure.in this method, assessment of seismic damage based on structure response, in different earthquake intensity and by damage state concept is done. ET method has been used for predicting response of models.in this investigation two conc. & steel models, with similar geometrical specification and different design results,... 

    Design and Fabrication of an Optimized Wake Equalizing Duct in Order to Improve Propulsion System Operation

    , M.Sc. Thesis Sharif University of Technology Ali Mirzazadeh, Siamak (Author) ; Seif, Mohammad S (Supervisor) ; Rad, Manouchehr ($item.subfieldsMap.e)
    Abstract
    Special geometrical sections, known as “duct”, which can be installed on merchant vessels stern in order to improve propulsion system and propeller performance, today have evolved considerably. The force which produces by the propeller depends on efficiency of propulsion system. In the way of improving the efficiency of propulsion systems, by using these special geometrical sections, to much research have been done from the mid-twentieth century. The Wake Equalizing Ducts (WEDs) in addition to conduct the more uniform fluid flow to the propeller disk (which causes to improve the propeller operation), affect on flow separation in ship stern zone and will decrease the separated flow zone.... 

    Fault Detection in Plant Wide

    , Ph.D. Dissertation Sharif University of Technology Tayyebi, Shokoufe (Author) ; Bozorgmehry, Ramin (Supervisor) ; Shahrokhi, Mohammad (Supervisor)
    Abstract
    The accurate fault diagnosing system design helps the process safety and also helps increasing the products quality of the process. In this project, the fuzzy system and neural network have been used for fault detection and diagnosis of a yeast fermentation bioreactor. In one case, parameters of membership functions are selected in a conventional manner. In second case, the optimal values of these parameters have been obtained using the genetic algorithm. In another case, the neural network system is used for fault detection. These three cases are compared based on their performances in fault diagnosis of a yeast fermentation bioreactor for three different conditions. The results indicate... 

    Algebraic Sets and Their Minimal Polynomials in a Division Ring, a General Setting

    , M.Sc. Thesis Sharif University of Technology Tayyebi, Saeed (Author) ; Mahdavi-Hezavehi, Mohammad (Supervisor)
    Abstract
    A Weddernurn polynomial over a division ring K, is the minimal polynomial of an algebraic subset of K. Such a polynomial, always is a product of linear factors over K, but not all such products are Wedderburn polynomials, even if these linear factors are distinct. In this thesis, we give some properties and characterizatios of Wedderburn polynomials over the division ring K, which relates deeply to algebraic subsets of K. We work in the general setting of Ore skew polynomials with an indeterminate t over K, corresponding to S,D, where S is an endomorphism of K and D is an S-derivation over K. Also we give a survey of the structure of the skew polynomial ring K[t; S; D] and its relation with... 

    Synthesis and Characterization of Graphene-based Material and Investigation of its Adsorption Properties for Radioactive Waste

    , Ph.D. Dissertation Sharif University of Technology Tayyebi, Ahmad (Author) ; 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... 

    Computational Simulation of Cooling of Porously Covered Surfaces, Using a Navier-stokes and Lattice Boltzmann Solver

    , Ph.D. Dissertation Sharif University of Technology Salimi, Mohammad Reza (Author) ; 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... 

    Computational Simulation of Supersonic Flow in an Axisymmetric Mixed Compression Inlet

    , M.Sc. Thesis Sharif University of Technology Zarea Chavoshi, Majid (Author) ; 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... 

    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 Rostamzadeh, Hadi (Author) ; 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... 

    Numerical Simulation of Bubble Cluster Dynamics, Using Lattice Boltzmann Method

    , Ph.D. Dissertation Sharif University of Technology Daemi, Mahdi (Author) ; 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... 

    Investigation of Flow over a Fin Located Downstream of a Supersonic Jet into Subsonic Crossflow

    , Ph.D. Dissertation Sharif University of Technology Hojaji Najafabadi, Mohammad (Author) ; 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... 

    Sustainable Analysis of Unions Uses Axiomatic Design Theory with Focus on European Union

    , M.Sc. Thesis Sharif University of Technology Torbati, Mostafa (Author) ; Malaek, S. M (Supervisor)
    Abstract
    In this project, we examine the stability or sustainability issue in unions, in other words we want to know whether integration in European Union is stable? Countries have positive attitude toward unions and being member in unions is at special priorities. The main reason for countires is improve economy and national Security.
    The main question in this research is modeling European Union with Axiomatic Design Theory and analysis of sustainability based on this theory. This study has attempted to push Axiomatic Design Theroy in the new field of Systems Engineering and also it gives a new and differnet approach to stability.