Sharif Digital Repository

In most real combustion systems, flow is turbulent (e.g., diesel engines). Therefore, a reliable turbulence modeling approach is necessary to design and analyze a system with turbulent flow. Direct numerical simulation (DNS), Large eddy simulation (LES), and Reynolds-averaged Navier-Stokes (RANS) are the three most mature Computational fluid dynamics (CFD) methods for turbulent flow simulations. Because of LES’s good accuracy and acceptable computational cost. In this project, LES is chosen to simulate the turbulent flow field.Modeled turbulence subgrid scales' interaction with nonlinear flow parameters, needs modeling. In supercritical and transcritical conditions, Equation-of-state is a... 

The swelling phenomenon in the porous media causes many problems in various engineering issues, including foundation construction and oil and gas extraction. For this reason, in the last few decades, flow modeling in reactive porous media and investigation of coupled hydro-chemo-mechanical problems have attracted a lot of attention. On the other hand, despite the simplifications, porous media have a heterogeneous structure, and the numerical modeling of these heterogeneities directly increases the computational costs. A suitable method for modeling heterogeneous problems is the computational homogenization method. In this method, the problem is solved in two scales in a correlated manner and... 

Osteoarthritis has always been one of the most common diseases in middle age because it causes severe pain and inflammation in the joints of the body. Cartilage tissue does not have the ability to repair itself. For this reason, fabricating and designing the most efficient, least-expensive, and most convenient methods for the treatment of cartilage defects is always an important issue. Today, there are surgical and injectable methods to relieve pain and initiate the body's natural healing response. But due to the many disadvantages and limitations of these methods, tissue engineering science has turned to modifying these methods or providing new methods. One of these methods is the use of... 

One of the most famous criteria to measure the optimality of the election result in the metric space is the amount of distortion. In this framework, the cost of choosing each candidate is considered equal to the total distance of the community members from that candidate. With this definition, the candidate who has the lowest selection cost among all the candidates is called the optimal candidate. The amount of distortion for an electoral mechanism is equal to the maximum amount of the cost of selecting the selected candidate divided by the cost of selecting the desired candidate. It turns out that no deterministic voting mechanism can guarantee a distortion value better than 3. Various... 

In this research, a comprehensive numerical model for Thermo-Hydro-Mechanical and Chemical multiphysics problems in fractured porous media was introduced using the eXtended Finite Element Method (XFEM), and its efficiency was demonstrated in two-dimensional problems. For the simplicity of the formulation and according to the common assumptions in the corresponding fields of study, the solid phase was assumed linear elastic and the flow was taken into account via Darcy's law. The system of governing equations comprised the linear momentum balance of the solid phase, mass conservation of pore fluids, thermal energy balance, and mass conservation of chemical species. The coupling of these... 

The purpose of this study is to simulate a turbulent premixed flame with the help of the Laminar Flamelet Decomposition method. Numerical simulation is considered the main approach for studying this flame. A Bunsen-type premixed burner, which has a novel approach to making different levels of turbulence, has been used for modeling the premixed flame. To reduce the cost of numerical calculations, the Reynolds-averaged Navier-Stokes approach has been chosen for the CFD simulation. In this study, the Laminar Flamelet Decomposition model is the main combustion model for analyzing the turbulent premixed flame and with this method, the rate of reactions for all the reaction species will be... 

The current research is one of the sections of the project for the design and construction of an Unmanned Surface vehicle (USV) , with the goal of extracting the dynamic model of the float using experimental tests. Initially, a literature review on system identification methods and the development of a dynamic model of the float has been conducted. Following that, the process of constructing and equipping a Catamaran platform for conducting tests and collecting suitable data for extracting the dynamic model has been described. Subsequently, tests have been conducted on the constructed float.Using the data obtained from the experimental tests, an artificial neural network has been employed to... 

The challenges of urbanization have been the focus of researchers since the past. With the expansion of urbanization and massive migration of people from villages to cities, these challenges became more important in our country. These issues, which exist in many other countries in a serious manner, are discussed in the branch of urban economy in the world. This thesis is arranged in three chapters, in each of which one of the aspects related to urban economy and housing is discussed. In the first chapter, the effects of the construction of Mehr housing on the value of nearby residential properties are investigated using difference-in-difference method. It is shown that the construction of... 

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... 

The Hamiltonian of the Hubbard model was introduced by Hubbard in 1963 to model electron correlations in narrow energy bands and it provided an approximate description of electrons in solids.This model provides a simple description of materials, but its exact solution is possible only in one dimension.In the physical examining of this model in quasi two-dimensional systems, the Density Matrix Renormalization Group(DMRG) is used, which is one of the most powerful numerical methods in studying quantum systems. The quantity that is important to solve the systems is the density matrix, which by knowing, many of the observable quantities of the systems can be obtained. Calculating the density... 

A Tension Leg Platform (TLP) can be difined as a vertically moored, buoyant and compliant platform, where the excess buoyancy of the platform maintains tension in the mooring system (tethers). This platform type is usually used for drilling in deep water and includes the following sections, foundation, tendons, risers, hull and deck which is the most important section in terms of hydrodynamic forces and weight. Enough initial tension can be used to inhibit vertical movement of the structure. one of The main properties of this oil platform is extraction at large oil fields. Body of TLP is consist of vertical column, horizontal circular or rectangular cross section Pantoons and circular... 

Wasteful approach in utilizing construction materials will result in depletion of resources and sacrificing future generations rights which is against sustainable development per se. As a corollary, presenting a new approach is aimed in this dissertation in order to decline avoidable building materials’ waste to the possible extent. This research focuses on wasted materials or construction waste. In this research, data about wastages of construction materials is gathered by surveying 32 residential buildings in Tehran. Afterwards, using multiple linear regression by IBM SPSS, wastages are quantified in terms of controllable independent variables namely floor area, number of stories, contract... 

Pulsating heat pipe (PHP) is a two-phase device for the means of transferring high heat fluxes and is used extensively for the electronic cooling. In this study the different flow regimes in PHP with different fluids have been investigated. In this research, 3 different fluids including: Pure fluids, Ferro-fluid and surfactant solution with %50 filling ratio have been used. For ferro-fluid, 5 different concentrations and 3 type of magnetic fields have been operated in 2 different heat pipes. Results show that ferrofluid is more stable in Pyrex made-heat pipe for long period of time and no magnet mode has the best thermal performance due to high conductivity of fluid. In copper made-heat pipe...