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    Three dimensional numerical simulation of air flow over domed roofs

    , Article NUMERICAL ANALYSIS AND APPLIED MATHEMATICS: International Conference on Numerical Analysis and Applied Mathematics, Corfu, 16 September 2007 through 20 September 2007 ; Volume 936 , 2007 , Pages 191-194 ; 0094243X (ISSN) ; 073540447X (ISBN); 9780735404472 (ISBN) Faghih Khorasani, A. R ; Bahadori, M. N ; Sharif University of Technology
    Using domed roofs to reduce building solar load in hot arid area is one of Iranian mechanical engineering masterworks. The first application of these roofs was to cover large buildings such as mosques, shrines, etc. However their thermal performance made them to be employed in other buildings like bazaars. The aim of this study was to determine the air pressure and velocity distribution over domed roofs, by employing numerical methods. The results of this study will be used as the first step for thermal performance evaluation of domed roofs. © 2007 American Institute of Physics  

    Numerical solution of transient flow in wind tunnels

    , Article Proceedings of the 7th Biennial Conference on Engineering Systems Design and Analysis - 2004, Manchester, 19 July 2004 through 22 July 2004 ; Volume 1 , 2004 , Pages 921-927 ; 0791841731 (ISBN); 9780791841730 (ISBN) Nouri Borujerdi, A ; Ziaei Rad, M ; Sharif University of Technology
    American Society of Mechanical Engineers  2004
    This paper deals with design and analysis of intermittent supersonic wind tunnels. System can be constructed by allowing air at atmospheric pressure to pass through a converging-diverging nozzle, a test section and a diffuser into a vacuum tank. The governing equations of compressible fluid flow have been solved numerically using flux vector splitting method to obtain running time under which it works at the design Mach number. The formulation has been tested on the theory of quasi one-dimensional compressible flow. The numerical results are in good agreement with the results of the theory  

    Numerical Solution of Stocastic Diffrential Delay Equation with Jump

    , M.Sc. Thesis Sharif University of Technology Samimi Ardestani, Mostafa (Author) ; Zohuri Zangeneh, Bijan (Supervisor)
    In this article we investigate the strong convergence of the Euler-Maruyama method and stochastic theta method for stochastic differential delay equation with jump .Under a global lipschitts condition we not only prove the strong convergence but also obtain the rate of convergence.We show stronge convergence under a local lipschits condition and linear growth condition.Moreover it is the first time we obtain the rate of strong convergence under a local lipschits condition and a linear growth condition.i.e if the local lipschitsz constants for balls of radius R are supposed to grow not faster than logR  

    Multigrid for Reservoir Simulation

    , M.Sc. Thesis Sharif University of Technology Negahdari, Vahid (Author) ; Razvan, Mohammad Reza (Supervisor)
    Reservoir simulation, recognition of the past and present reservoir behavior and prediction of its behavior in the future, which forms one of the most important parts of the management of a reservoir. In fact, the reservoir is like a living creature and increasing the accuracy in predicting its behavior requires a precise model. Reservoirs have high physical dimensions that are associated with high physical changes. As a result, a large number of computational cells are needed to simulate the reservoirs, which results in a very large linear equation system. The numerical solution of these systems is very time consuming. Many observed examples indicate that 80 \% of the runtime is included.... 

    Numerical Solution of Stochastic Differential Equations with Different Methods

    , M.Sc. Thesis Sharif University of Technology Qeysari, Mahmood (Author) ; Zohuri Zangeneh, Bijan (Supervisor) ; Razvan, Mohammad Reza (Supervisor)

    Inertial microfluidics: a method for fast prediction of focusing pattern of particles in the cross section of the channel

    , Article Analytica Chimica Acta ; Volume 1083 , 2019 , Pages 137-149 ; 00032670 (ISSN) Mashhadian, A ; Shamloo, A ; Sharif University of Technology
    Elsevier B.V  2019
    Inertial microfluidics is utilized as a powerful passive method for particle and cell manipulation, which uses the hydrodynamic forces of the fluid in the channel to focus particles in specific equilibrium positions in the cross section of the channel. To achieve high performance manipulation, knowledge of focusing pattern of particles in the cross section of channel is essential. In this paper, we propose a method to address this important issue. To this end, firstly inertial microfluidics is analyzed in rectangular cross section channels. The results indicate that fluid flow velocity and channel's cross-sectional profiles have great impacts on the forces exerted on particles. Next, these... 

    Investigating the Impact of Different Topologies on Performance of Catalytic Converters

    , M.Sc. Thesis Sharif University of Technology Sadeghi, Mohammad Amin (Author) ; Kariminia, Hamid Reza (Supervisor) ; Abdekhodaie, Mohammad Jafar (Supervisor)
    Due to their enormous CO/〖NO〗_x removal capabilitiy, catalytic converters are deemed as indispensable parts of modern vehicles. These converters are comprised of a bundle of parallel tubes which their internal walls are wash-coated with a catalyst such as platinum or rhodium. The typical geometry for the tubes’ cross-section is honeycomb. In this project, the effect of tube cross-section geometry on CO/〖NO〗_x removal performance of catalytic converters is studied. In this respect, a three-dimensional model consisted of incompressible flow, advection-diffusion, and surface reaction was developed. Candidate geometries were triangle, square, honeycomb, and circle. The results show that as the... 

    Numerical Investigation of Dewetting Over Topographicaly Srtuctured Substrate on Nanometric Scale

    , M.Sc. Thesis Sharif University of Technology HajiGhasemi, Mustafa (Author) ; Moosavi, Ali (Supervisor)
    Thin liquid films on solid substrates are of considerable relevance in widespread of natural and technological fields. Examples are eye irrigation, biological cell interaction, tertiary oil recovery, coating, painting, lubrication, integrated circuits, micro- and nano-electronic devices, to name just a few. It is well known that liquid films are not always stable and there are verities of factors that may destabilize and expose the film to dynamical processes which leads to removal of the liquid from the substrate, the phenomenon so-called dewetting, either by nucleation or spinodal mechanisms. In many cases dewetting is destructive but there are several situation in which dewetting turns... 

    Numerical Simulation and Enalysis of an Electrokinetically-driven Microdispenser

    , M.Sc. Thesis Sharif University of Technology Haroutunian, Artin (Author) ; Saeedi, Mohammad Saeed (Supervisor) ; Shafiee, Mohammad Behshad (Supervisor)
    Nowadays Lab-on-a-chip systems are being widely used in medical applications, especially in analyzing minute volumes of blood for diagnosis and treatment of some crucial diaseses like diabetic. A Lab-on-a-chip is comprised of a variety of components such as micromixer, microdispenser, detection and separation units and so on. In this thesis, however, we have analyzed and numerically simulated a microdispenser which is electrokinetically driven. In other words, electrical potentials are applied to electrodes in order to conduct two fluids within a cross microchannel, and distribution of a sample fluid takes place due to appropriately applied potentials. In order to analyze and simulate the... 

    Numerical Simulation of Turbulent Flow Heat Transfer in the Entrance Region of Microchannels

    , M.Sc. Thesis Sharif University of Technology Sadeghi, Arman (Author) ; Nouri Borujerdi, Ali (Supervisor)
    In this thesis the steady state convective heat transfer for turbulent, two-dimensional, incompressible gas flow in a circular microchannel under slip flow and temperature jump conditions is numerically investigated by means of finite volume scheme. The low Reynolds number k-ε turbulence model is employed using a new boundary condition for turbulent kinetic energy at solid surface. To calculate variables at control volume surfaces in the axial direction upwind differencing scheme and in the radial direction central differencing scheme are used. Rhie-Chow interpolation technique is used to prevent pressure field oscillations. The set of discrete equations are solved using SIMPLE Algorithm. In... 

    Heat Transfer in Uniform Suction Porous Media of Micro Channel with Variable Cross-section

    , M.Sc. Thesis Sharif University of Technology Akrami, Hamid Reza (Author) ; Nouri Borujerdi, Ali (Supervisor) ; Kazemzadeh Hannani, Siamak (Supervisor)
    Fully developed fluid flow and heat transfer is numerically investigated in micro-channels. There are many techniques to intensify heat transfer for internal flows, such as: increasing Reynolds number, extending surface area of channel wall and also disrupting the boundary layer thickness on the wall. Among these, extension wall surface area is a common technique. There are several ways to extend surface area including finned, slotted, chemically etched, grooved as well as porous media adhered wall surface. One other method that we work on it is modifying wall cross-section and usage of uniform suction porous media. The governing equations include the momentum equation of the core region... 

    Numerical Investigation of Non-Fourier Heat Conduction in Human Skin

    , M.Sc. Thesis Sharif University of Technology Hodjat, Reza (Author) ; Taghizade Manzari, Merdad (Supervisor) ; Sani Joushaghani, Mahdi (Supervisor)
    When classical Fourier law of heat conduction is not applicable due to finite speed of heat propagation in a medium, non-Fourier heat conduction is used. In non-Fourier heat conduction, heat transfer is studied considering finite speed of heat flux (thermal wave) or temperature gradient or both (dual phase lag). Biological tissues like skin are one of the materials which show non-Fourier behavior during usual heating processes. In this research heat transfer in human skin is modeled by Fourier, thermal wave and dual phase lag (DPL) models. The equations are solved using the finite difference method and the temperature distribution across the tissue is calculated. In thermal wave model,... 

    Mathematical Modeling of Airlift Slurry Reactor for Removal of Hydrogen Sulfide (Hydrodesulfurization)

    , M.Sc. Thesis Sharif University of Technology Khadem Hamedani, Behnam (Author) ; Yaghmaei, Soheila (Supervisor) ; Mashayekhan, Shohreh (Co-Advisor)
    After carbon and hydrogen the most existed element in crude oil is sulfur which is appeared as sulfur compound in fossil fuels. Sulfur might be converted to hydrogen sulfide by hydrodesulphurization operation. The increasing demand for sulfur removal has required large improvements in hydrodesulphurization technology.Most hydrodesulphurization processes use fixed-bed reactors, however, there are still some disadvantages with performing hydrodesulphurization in these reactors. The most important one is high exothermic nature of hydrodesulphurization process which cause some problems for catalyst in these reactors and decrease the performance of catalyst. In order to solve the temperature... 

    General solution to wave propagation in media undergoing arbitrary transient or periodic temporal variations of permittivity

    , Article Journal of the Optical Society of America B: Optical Physics ; Volume 35, Issue 11 , 2018 , Pages 29232932- ; 07403224 (ISSN) Chegnizadeh, M ; Mehrany, K ; Memarian, M ; Sharif University of Technology
    OSA - The Optical Society  2018
    A novel and general formulation for wave propagation in time-varying media is presented. Unlike previousreports, our formalism is able to solve propagation in media with arbitrary time variations of permittivity orpermeability, for both transient and steady-state periodic variations. The formulation is approximate yet strikingly accurate in most practical cases. The provided closed-form expressions show that the normalized averagepower after the transition of the permittivity does not depend on the details of the transition, while the energydensity does. Some important discussions are made about time-periodic media, and it is shown that there is anaccumulation of energy when the temporal... 

    Evaluation of FPGA Hardware as a New Approach for Accelerating the Numerical Solution of CFD Problems

    , Article IEEE Access ; Volume 5 , 2017 , Pages 9717-9727 ; 21693536 (ISSN) Ebrahimi, A ; Zandsalimy, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2017
    The main purpose of this paper is to investigate the feasibility of using field programmable gate arrays (FPGAs) chips as alternatives for the conventional CPUs to accelerate the numerical solution of the fluid dynamics differential equations. FPGA is an integrated circuit that contains an array of logic blocks, and its architecture can be reprogrammed and reconfigured after manufacturing. Complex circuits for various applications can be designed and implemented using FPGA hardware. The reconfigurable hardware used in this paper is a system on a chip FPGA type that integrates both microprocessor and FPGA architectures into a single device. In this paper, typical computational fluid dynamics... 

    Modeling of Fluid Flow and Heat Transfer in a Partially Filled Porous Channel with Wall Suction

    , M.Sc. Thesis Sharif University of Technology Hashemi, Mir Hossein (Author) ; Nouri-Borujerdi, Ali (Supervisor)
    This work numerically simulates pressure drop and heat transfer for flow in a pipe with porous wall. Incompressible two dimensional, ax symmetric laminar or turbulence flow with constant mass flow rate is considered. It is assumed that there is no thermal equilibrium in the porous media region between solid and fluid phase. Effect of porous wall thickness and Darcy number on the rate of heat transfer and pressure drop were investigated. The Darcy number varies from to and porous wall thickness can fill entire pipe. the turbulent model is used to calculate the fluid flow and heat transfer characteristics in turbulent flow. Nusselt number can enhance about ... 

    Auto thermal reforming of natural gas
    Surveying Feed Specification on the Effluent Quality as the Feedstock of a Methanol Unit and its Optimization

    , M.Sc. Thesis Sharif University of Technology abtahi, mohammad hossein (Author) ; farhadi, Fatollah (Supervisor)
    Synthesis gas is a gaseous mixture which mainly consists of carbon monoxide and hydrogen. Different methods are used to produce synthesis gas but the most important method is auto thermal reforming. This method is based upon catalytic reactions. Steam, oxygen and natural gas are the influents to the reactor and synthesis gas will be the effluent. Ni catalysts on alpha-alumina as the support media are usually used in this process. These catalysts are highly heat resistant and insure great qualifications for reactions. This thesis tries to find best solutions of synthesis gas production suitable for feeding to a methanol production unit. There are four main reactions. Three of which are highly... 

    Performance of Partially Filled Mini-Channels with Porous Media

    , M.Sc. Thesis Sharif University of Technology Azimi, Adel (Author) ; Nouri, Ali (Supervisor) ; Moosavi, Ali (Co-Advisor)
    Laminar forced convection flow through a channel partially filled with a porous material was numerically studied in this thesis. The Navier-Stokes and Brinkman-Forchheimer equations were used to model the fluid flow in the free and porous regions, respectively. Coupling of the pressure and velocity fields was resolved using the SIMPLEC algorithm. The local thermal equilibrium was adopted in the energy equation. The effects of the thermal conductivity ratio, Darcy number, porosity, Reynolds number and height of the porous insert on velocity and temperature field were investigated. The results show that the flow behavior and its associated heat transfer are susceptible to the variation of the... 

    Some Innovations in Numerical Simulation of Inviscid Three Dimensional Flow with Moving Boundaries

    , Ph.D. Dissertation Sharif University of Technology Ramezani, Ali (Author) ; Mazaheri, Karim (Supervisor)
    The main subject of this thesis is to improve conventional CFD algorithms applied in numerical simulation of inviscid unsteady flows around moving boundaries with large relative motions, on unstructured grids. All challenges in this regard are reviewed, and appropriate efficient schemes are introduced to address them. A new scheme is presented for valid grid generation during grid movement and is implemented for 2D and 3D problems. Customary three dimensional convergence acceleration techniques such as implicit time stepping and multigriding have been applied. For implicit solution of the flow equations a new algorithm is used. Via a special renumbering algorithm, the approximate... 

    Investigation of Atrium Shape Influence on Natural Ventilation Performance & CFD Model

    , M.Sc. Thesis Sharif University of Technology Shafiee, Ali (Author) ; Moosavi, Ali (Supervisor)
    In modern era, standpoints about atrium design have been revolutionized. In modern architecture, atrium not only designed for illuminating purposes but also designed by natural ventilation and passive cooling policies. Numerous parameters are making role in thermal efficiency of Atrium. A couple of these parameters are Atrium shape and openings area. In high rise atria the lower level rooms enjoy the advantage of buoyancy-driven ventilation while the upper level rooms suffer from its lack or weak presence. One strategy to solve this problem is designing building with various opening area in different heights but manipulating the opening size is restricted by some facts. Excessive Opening’s...