Search for: three-dimensional-simulation
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    Numerical study on the performance of Tesla type microvalve in a valveless micropump in the range of low frequencies

    , Article Journal of Micro-Bio Robotics ; Volume 8, Issue 3 , 2013 , pp 145-159 ; 21946418 (ISSN) Mohammadzadeh, K ; Kolahdouz, E. M ; Shirani, E ; Shafii, M. B ; Sharif University of Technology
    In this study, the performance of Tesla-type microvalves, used in micropumps for low frequency driving force, is examined. Three-dimensional and unsteady numerical analysis of fluid flow inside a valveless reciprocating micropump in the range of low working frequencies is carried out. Reciprocating movement of flow actuator provides the actuation and pumping of the working fluid. Ferrofluidic valveless micropump is one practical sample of this kind of micropumps that operate in the range of low working frequencies. To model the reciprocating movement of flow actuator, two time varying functions that includes sinusoidal and step excitation are employed. Also, the performance of... 

    Axisymmetric and three-dimensional flow simulation of a mixed compression supersonic air inlet

    , Article Propulsion and Power Research ; Volume 9, Issue 1 , 2020 , Pages 51-61 Abedi, M ; Askari, R ; Sepahi Younsi, J ; Soltani, M. R ; Sharif University of Technology
    Elsevier Ltd  2020
    The flow through an axisymmetric supersonic mixed-compression air inlet has been simulated numerically to investigate the effects and the necessity of the three-dimensional (3D) modeling in comparison with the axisymmetric one. For this purpose, a supersonic inlet has been simulated numerically via axisymmetric and 3D CFD solvers, using the steady state Reynolds-averaged Navier-Stokes equations along with the SST k-ω turbulence model, for a free-stream Mach number of 2.0 and at zero degrees angle of attack. The grid for the 3D cases was a 14.4-degree sector, instead of a 360-degree domain one, with rotational periodic boundary condition for the side boundaries. The results show that both... 

    Numerical Analysis of Effects of Twin Swirler Injector on Turbine Combustion Chamber Performance

    , M.Sc. Thesis Sharif University of Technology Jalalabadi, Abolfazl (Author) ; Farshchi, Mohammad (Supervisor)
    The objective of current research is to investigate the effects of Twin Swirler Injector on performance of turbine combustor. For this purpose, the swirlcup is assessed in a dump combustion chamber. The resultant simplicity in geometry leads to a facilitation in parametric studies as well as a reduction in modeling and meshing time. The target swirlcup, is a simplified model of CFM56 engine’s swirlcup.
    Standard k-ε model is established to take into account turbulence effects. The non-reacting flow is at first simulated for capturing and recognising different phenomena. Adiabatic reacting flow simulations are conducted with Probability Distribution Function using Steady Laminar Flamelet... 

    Completely 3dimensional Simulation of Urine Concentrating Mechanism in Rat Outer Medulla

    , M.Sc. Thesis Sharif University of Technology Sohrabi, Salman (Author) ; Saidi, Mohammad Said (Supervisor) ; Firoozabadi, Bahar (Co-Advisor)
    The urine formation and excretion system has long been of interest for mathematicians and physiologists to elucidate the obscurities within the process happen in renal tissue. In this study, a novel and absolutely three-dimensional approach is utilized for modeling urine concentrating mechanism in rat renal outer medulla which is essentially focused on demonstrating the significance of tubule's architecture revealed in anatomic studies and physiological literature. Since nephrons and vasculatures work interdependently through a highly structured arrangement in outer medulla which is dominated by vascular bundles, a highly detailed functional unit is proposed and also it is strongly justified... 

    Simulation of Urine Concentrating Mechanism in Rat Kidney Inner Medulla

    , M.Sc. Thesis Sharif University of Technology Sanatkhani, Soroush (Author) ; Saeedi, Mohammad Saeed (Supervisor)
    Physicians use charts that are prepared by experiments on animals or humans to prescribe drug dosage for patients. This method requires much more time by the Ministry of Health to approve new drugs to be used in health-care centers. Furthermore،we have no sight on how a specific drug is going to be diffuse in our body. In order to predict the distribution of a drug or any minerals in the kidney we need to model it. The first step would be modeling the important species that influence the urine concentrating mechanism. Due to the complications in modeling that mechanism especially in the inner medulla zone، we hadn’t solid information regarding that area. It is about half a century that... 

    Aerodynamic Design of Twin-entry Radial-inflow Turbine's Impeller

    , M.Sc. Thesis Sharif University of Technology Vaezi, Siavash (Author) ; Hajilouy Benisi, Ali (Supervisor)
    The purposes of this research are one and three dimensional aerodynamic designs of a twin entry radial-inflow gas turbine's impeller. The GT4082 model Garrett turbocharger was chosen for this purpose. In order to predict existing turbine performance curves one dimensional model was prepared for whole turbine. For validating the 1d-modeling's results, widespread tests were performed on the turbine at Sharif University of Technology turbocharger lab. Comparing the results of 1d-modeling with experimental results, show 4.7% and 4% max difference for efficiency and mass parameter respectively. The wheel designing procedure started from primary design based on the mean line assumption, in 1-d... 

    Three Dimensional Simulation and Experimental Modeling of Two Stage GM Type Pulse Tube Refrigeration with Double-Inlet

    , M.Sc. Thesis Sharif University of Technology Ashouri, Mahyar (Author) ; Saidi, Mohammad Hassan (Supervisor)
    There are numerous ways available to achieve low temperatures that cryocoolers might be among the most important of them. In the meantime, the pulse tube refrigerator has a special place due to its simple geometry and not be using any moving parts. This simple property make the pulse tube refrigerator one of the most popular methods to achieve low temperatures. Nowadays, a pulse tube refrigerator is used for cooling in the range of 4 to 123 Kelvin in two form of one-stage and two-stage and up to an approximate power of 1 KW. Today, due to the temperature and the amount of power required for cooling, as well as the time it takes to reach that temperature, this chiller is used in medical,... 

    Thermo acoustic study of carbon nanotubes in near and far field: Theory, simulation, and experiment

    , Article Journal of Applied Physics ; Volume 117, Issue 9 , 2015 ; 00218979 (ISSN) Asadzadeh, S. S ; Moosavi, A ; Huynh, C ; Saleki, O ; Sharif University of Technology
    American Institute of Physics Inc  2015
    Carbon nanotube webs exhibit interesting properties when used as thermo-acoustic projectors. This work studies thermo-acoustic effect of these sound sources both in near and far field regions. Based on two alternative forms of the energy equation, we have developed a straightforward formula for calculation of pressure field, which is consistent with experimental data in far field. Also we have solved full 3-D governing equations using numerical methods. Our three-dimensional simulation and experimental data show pressure waves are highly affected by dimensions of sound sources in near field due to interference effects. However, generation of sound waves in far field is independent of... 

    Three-dimensional process cycle simulation of composite parts manufactured by resin transfer molding

    , Article Composite Structures ; Volume 65, Issue 3-4 , 2004 , Pages 381-390 ; 02638223 (ISSN) Shojaei, A ; Ghaffarian, S. R ; Karimian, S. M. H ; Sharif University of Technology
    A process cycle of resin transfer molding (RTM) consists of two sequential stages, i.e. filling and curing stages. These two stages are interrelated in non-isothermal processes so that the curing stage is dominated by the resin flow as well as temperature and conversion distributions during the filling stage. Therefore, it is necessary to take into account both filling and curing stages to analyze the process cycle accurately. In this paper, a full three-dimensional process cycle simulation of RTM is performed. Full three-dimensional analysis is necessary for thick parts or parts having complex shape. A computer code is developed based on the control volume/finite element method (CV/FEM).... 

    Three Dimensional Simulation of Morphology of Nanodroplets Near and on Structured Substrates

    , M.Sc. Thesis Sharif University of Technology Vahid, Afshin (Author) ; Moosavi, Ali (Supervisor)
    Mesoscopic hydrodynamic equations are solved employing a VOF based method to investigate the equilibrium shape of nanodroplets positioned over various topographic geometries of the supporting substrate for three-dimensional systems. By taking into account liquid-liquid and liquid-solid interactions a complex distribution for inter-molecular forces over the substrates (the disjoining pressure) is observed. In this research we show that motion of nanodroplets not only caused by contact angle difference in drplets two sides, but also depend on disjoining pressure parameters.Geometries with increasing complexities, from wedges to three dimensional edges and wedges, were explored with the main... 

    Migrating From 3D Modelling of the Laser Assisted Machining Process into a Valid 2D Model

    , M.Sc. Thesis Sharif University of Technology Mousavi, Mohammad Amin (Author) ; Movahhedy, Mohammad Reza (Supervisor)
    Due to recent advances in laser technology and instruments, laser assisted machining processes has gained extra attention by scientists and industries. Naturally, effective modeling of the process is of great interest for researchers. Machining processes are generally modeled via FE tools and based on the requirements of model, it can be performed either mechanically or thermos-mechanically. About the LAM problems, it is basically meaningless to have a model without considering thermal effects. Hence, modeling is performed in two steps where through the first one, a thermal problem is solved to bring the temperature distribution of the work piece as the initial conditions of the next step.... 

    Numerical Simulation of A Vortex Cooled Combustion Chamber

    , M.Sc. Thesis Sharif University of Technology Azardar, Milad (Author) ; Farshchi, Mohammad (Supervisor)
    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... 

    Three Dimensional Fluid-structure Interaction Analysis of Air Flow and Inhaled Particle Transport in Human Pulmonary Alveoli

    , Ph.D. Dissertation Sharif University of Technology Monjezi, Mojdeh (Author) ; Saeedi, Mohammad Saeed (Supervisor)
    The prediction of deposition efficiency of submicron particles in the pulmonary alveoli has received special attention due to its importance for drug delivery systems, and for assessing air pollutants health risks. In this work, the pulmonary alveoli of a healthy human are idealized by a three dimensional honeycomb like configuration and a fluid-structure interaction analysis is performed to study the normal cyclic breathing hydrodynamics. A viscoelastic model is used for the mechanical behavior of alveolar wall tissue. In contrast to previous works in which the inlet flow rate is predefined, in this model a negative pressure is imposed on the outside surface of the alveolus which causes air... 

    Comparison of Transfer Functions in Dual Porosity-Dual Permeability Models in Simulation of 3D Black-Oil Naturally Fractured Reservoirs Using Structured Grids

    , M.Sc. Thesis Sharif University of Technology Mohammadnejad, Hamed (Author) ; Taghizadeh Manzari, Mehrdad (Supervisor)
    In this work, simulation of 3D three-phase naturally fractured reservoirs is studied. Both Dual Porosity and Dual Porosity-Dual Permeability models which are commonly used in commercial softwares such as ECLIPSE and CMG, are utilized. The governing equations include the mass (in Black-oil model) and linear momentum (in Darcy law form) equations, which are converted into pressure equations and a set of transport equations for the saturations and mole fractions of phases. These equations are solved once for the matrix domain and subsequently for the fracture domain. These two set of equations are coupled through transfer functions. The accuracy of computations significantly depends on how... 

    Investigation of the Fire-Induced Smoke Flow in the Complex Geometries Using The 3d Numerical Method and the Body-Fitted Curvilinear Coordinates

    , Ph.D. Dissertation Sharif University of Technology Savalanpour Ardebili, Hamid Reza (Author) ; Farhanieh, Bijan (Supervisor) ; Afshin, Hossein (Co-Supervisor)
    With the process of achieving a higher state of social development and technological advances, the need for higher and more strict safety standards has been increased. In this regard, it is of great importance to have an accurate understanding of the fire phenomena and its consequences. Among the adverse effects of fire, a significant percentage of the fire fatalities is related to the fire-induced buoyant gases (smoke) flow which can lead to suffocation. Therefore, it is necessary to know the physics of the fire phenomena well. In fire investigation methods, the numerical study is an appropriate choice, because of the lower executive cost (relative to the experimental study) and the wider... 

    A guidance algorithm for launch to equatorial orbit

    , Article Aircraft Engineering and Aerospace Technology ; Volume 81, Issue 2 , 2009 , Pages 137-148 ; 00022667 (ISSN) Marrdonny, M ; Mobed, M ; Sharif University of Technology
    Purpose - The purpose of this paper is to propose a new guidance algorithm for launching a satellite using an expendable rocket from an equatorial site to an equatorial low-Earth orbit. Design/methodology/approach - Guidance during endoatmospheric portion is based on a nominal trajectory computed prior to take-off. A set of updating computations begins anew at the time instant tg of transition from endoatmosphere to exoatmosphere. The updating computations determine a guidance trajectory and an associated control law for the remainder of path by taking into account the rocket state at time tg. Thus, the overall guidance involves both initial and midcourse operations, and it has both open-... 

    Numerical investigation of rectangular-cut twisted tape insert on performance improvement of heat exchangers

    , Article International Journal of Thermal Sciences ; Volume 138 , 2019 , Pages 75-83 ; 12900729 (ISSN) Nakhchi, M. E ; Esfahani, J. A ; Sharif University of Technology
    Elsevier Masson SAS  2019
    A numerical analysis has been performed to investigate the flow structure and thermal hydraulic performance of turbulent flow through circular tube equipped with twisted tapes with different cut shapes. The geometries of cuts are rectangular with different cut ratios 0.25

    L1 Adaptive integrated guidance and control for flexible hypersonic flight vehicle in the presence of dynamic uncertainties

    , Article Proceedings of the Institution of Mechanical Engineers. Part I: Journal of Systems and Control Engineering ; Volume 235, Issue 8 , 2021 , Pages 1521-1531 ; 09596518 (ISSN) Khankalantary, S ; Rezaee Ahvanouee, H ; Mohammadkhani, H ; Sharif University of Technology
    SAGE Publications Ltd  2021
    In this article, an integrated guidance and control design method for general nonlinear flexible hypersonic flight vehicles in the presence of dynamic uncertainties based on the (Formula presented.) adaptive state feedback control approach is presented. Initially, the 6-degree-of-freedom integrated guidance and autopilot dynamic model is organized using the combination of flexible uncertain hypersonic flight vehicle dynamic model and hypersonic flight vehicle-target relative motion model whereas aerodynamic and model uncertainties, cross-coupling effects, and disturbances are considered. The proposed integrated guidance and control method based on (Formula presented.) adaptive control scheme... 

    Aerodynamic enhancement and improving the performance of a six-megawatt dowec wind turbine by micro-plasma actuator

    , Article International Journal of Mechanical Sciences ; Volume 195 , 2021 ; 00207403 (ISSN) Omidi, J ; Mazaheri, K ; Sharif University of Technology
    Elsevier Ltd  2021
    We have investigated the usage of a Dielectric Barrier Discharge (DBD) plasma actuator to improve the aerodynamic performance of an offshore 6 MW wind turbine. By controlling the aerodynamic load combined with pitch angles of 2, 5, and 10 degrees, we studied the plasma actuator effect on the overall harvested power. Actuators were installed in single and tandem configurations in different chord-wise locations to find the optimum design. The improved phenomenological model developed by authors was used in an analysis to simulate the interaction of the electrostatic field, the ionized particles and the fluid flow. A design software was used to estimate the harvested power of the real 3D blade.... 

    Theoretical and experimental investigation of design parameter effects on the slip phenomenon and performance of a centrifugal compressor

    , Article Scientia Iranica ; Volume 28, Issue 1 , 2021 , Pages 291-304 ; 10263098 (ISSN) Rajabpour, S ; Hajilouy Benisi, A ; Manzari, M. T ; Sharif University of Technology
    Sharif University of Technology  2021
    Numerous studies have investigated driving equations used to predict the slip factor in centrifugal compressors so far. Inevitably, through these studies, the ow field characteristics have been simplified and the effects of the related parameters have been neglected. The present study, experimentally and numerically, investigates the slip phenomenon in a specific centrifugal compressor with complex blade curves and splitter blades, considering the main effective parameters such as the number of blades, exit angle, etc. To this end, a three-dimensional simulation of the viscous flow field of the compressor via an appropriate turbulence method was performed. In addition, an experimental study...