Sharif Digital Repository

Iran is one of the biggest suppliers of oil in the world. Iran's economy highly depends on its oil. Iran has valuable old reservoirs that need some techniques to optimize their production of it.Determining optimal well placement and control is essential to maximizing production from an oil field. The reservoir optimization problem is an extraordinary complex problem that depends on many factors such as flow pattern, well specification, reservoir properties, and environmental and economic criteria. Finding the locations of injection and production wells and other optimum operational parameters in the oil industry are very important and have a great influence on the operation of the... 

In water service processes, tubular heat exchangers are commonly used to provide a heat transfer medium for cooling or heating of which both are subject to fouling of heat transfer surfaces. The deposit would dominantly build up in form of fouling, crystallization, and or particulate fouling depending on the operating and surface conditions. This, in turn, may result in more demand for excessive energy consumption due to higher pumping requirements, as well as for offsetting the impact of fouling. Introducing the subject of the on-line condenser tube cleaning system as a most effective way of encountering with deposits and its components, the difficulties encountered during operation and... 

One of the newest technologies in order to separate oil from water and also oil wastewater is the axial vortex separator technology (with commercial name of voraxial). In the current project, we analyze one of the voraxial (2000) separator systems types. In the modeling of voraxial system, we utilize a 3D model which is developed on the basis of commercial sample of voraxial 2000 technology, and conduct the solution of particles and fluid with Lagrangian Eulerian approach. Considering the k-ɛ turbulence model and an incompressible flow with the input of 30GPM and rotational velocity of 400RPM was another segment of the project. Due to the largeness of 10µ particles diameter, the Brownian... 

Innovations in laser, microwaves, and similar technologies have significantly advanced thermal treatments for diseases or even injuries concerning skin tissue. For a thorough understanding in the underlying mechanisms of bioheat transfer behavior of skin,a1D unsteady non-dimensional hyperbolic model of heat transfer through this tissue with metabolic heat generation which is subject to specific boundary conditions, is solved numerically using the finite difference method. A thermal shock is generated at the base of the tissue, which moves forward with a finite speed. A Numerical solution for a simple one-layer skin tissue is obtained. Then, the effects of various parameters, time step,... 

In this research, a simple yet efficient two-dimensional model of proton exchange membrane fuel cell (PEMFC) is developed using stream function-vorticity formulation. The model accounts for the fluid flow and masstransport processes in cathode gas channel and gas diffuser layer. The governing equations are decoupled and solved usingtwo efficient approaches, Alternating Direction Implicit (ADI) and False Transient Method (FTM) in a modified geometry to simulate the fully-developed condition consistently. An in-house code was developed to perform a parametric study of fuel cell performance. The results show the variations of important parameters along the cathode channel such as velocity... 

Performance of Polymer Electrolyte Membrane Fuel Cells (PEMFC) at high current densities is limited to transport of reactants and products. Also at high currents, large amounts of water are gener-ated due to electrochemical reactions. Due to low temperature of PEMFC, some of the steam condenses. The amount of water existing in a PEMFC influences its performance. Shortage of water adversely af-fects cell performance by drying out the membrane. On the other hand, an excessive amount of water blocks pores of porous medium and transport of fuel becomes difficult.
In order to predict flooding and its effects on the PEMFC performance, development of a two-phase flow model is necessary. In this... 

In this thesis the oil reservoir simulation is carried out by using a combination of fast Multi-scale finite volume method and Streamline method considering gravity effects. In this simulation, the governing equations for incompressible fluid flow in porous media are solved using the IMPES (implicit pressure- explicit saturation) viewpoint. Multi- scale method is rapid (equivalent on coarse-scale methods) and accurate (equivalent on fine-scale methods) in solving the pressure field. Using the pressure field obtained through this way combined with Darcy equation make us able to extract the conservative velocity field. In this study, analytical and numerical Streamline methods are used to... 

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... 

Measuring flow rate in various industries is an operational challenge that requires to be accurate and fast to avoid wasting energy and money. Various flowmeters are employed in different industries using different principles and methods. Sonar flowmeters are one of the acoustic methods of fluid flow measurement, which do this by listening to the sound of the flow via arrays of sensors. Sonar flow measurement can be achieved by finding either the convection velocity of eddies or the speed of sound in the fluid. The first method is suitable for measuring single-phase flows, which is the subject of this thesis. This method needs a detailed study of turbulence. In the present work, this is... 

One of the methods of measuring the flow rate in a pipe (channel) is by using the acoustic waves with long wavelenghs in Sonar flowmeters. This flowmeter consists of an array of sensors, mounted on the outer wall of the pipe. These sensors by listening and interpreting the sound waves passing through the fluid, would give a “non-intrusive” measurement of the volumetric flow rate. This means that the flowmeter is not in direct contact with the flow and therefore its repair, relocation or replacement will not disturb the flow. In this project, we will provide a clear understanding of the principles and physics involved in sonar-based acoustic flowmeters, by means of numerical simulation of the... 

This study presents an integrated two-dimensional numerical framework for simulating rainfall-induced landslides from instability initiation to post-failure flow. The discrete element method (DEM) is used to establish a rheological model that relates the apparent viscosity of a granular sand to shear rate, normal stress, and water saturation. A theoretical model is developed to determine water distribution and water-induced forces between particles for different saturations. The resulting forces are embedded in a 3D shear cell as a numerical rheometer and a wet sand is sheared between two walls. A power law rheological model is obtained as a function of inertia number and saturation. It was... 

The main goal of this study is simulation of the flow-like landslide phenomenon and investigation of the effect of bed material entrainment on its behavior. Debris flows are considered as one of the types of flow-like landslides, and flow of dry granular materials on horizontal and inclined beds as a simple model of these types of flows in nature is numerically simulated. Also, in order to investigate the effect of entrainment on dynamics of flow, a bed containing granular materials is installed on horizontal and inclined beds. The governing equations of the flow are solved in the continuum context using the Smoothed Particle Hydrodynamics (SPH) method and the depth-averaged assumptions are... 

Reservoir simulation is a useful tool for efficient reservoir management and protective exploitation of non-renewable hydrocarbon resources as the main supplier of development programs in the country. Due to the nature of underground hydrocarbon reservoirs, the simulation faces several challenges, both in rock and fluid parts. These challenges should be overcome in order to provide reliable results from simulations. One of the major challenges pertaining to rock, is large discontinuous variations accompanied by anisotropy of rock permeability fields which causes numerous problems when governing equations are solved numerically. A viable numerical procedure shall account for complex reservoir... 

Magnetorheological fluids are suspensions of magnetic solid particles suspended in a nonmagnetic matrix fluid. By imposing an external magnetic field, particles are arranged in microstructures aligned with the external field and hence, dramatically affect the fluid flow. Since the strength of the magnetic field determines the resistance of these microstructures against flow, the rheology of the suspension is a function of the intensity of the external magnetic field. The goal of the present work is to study the role of non-gap-spanning magnetic clusters on the rheology of a magnetorheological fluid. Here, first a robust tool for direct numerical simulation of magnetic suspensions is... 

In this project، the immiscible two phase flow of oil-water in the absence of gravity in the two dimensional domain is investigated. The uncertainty quantification of pressure and saturation of fluid in the reservoir are calculated by the methods of statistical moment equation (presented by Tchelepi) and probabilistic collocation method combined with Karhunen Loeve expansion (presented by Heng Lee). Then the results are compared with Monte Carlo simulation. Matlab Reservoir Simulation Toolbox is used for flow simulation. The main problem based on Tchelepi’s work[56[ ، is a horizontal two dimensional problem that there is two injection and production wells at the two end point grids (a... 

Physics of present work is 2D and two phase immiscible flow under gravity and capillary effect through fractured porous media. Rock properties such as porosity and permeability are homogenous. Discrete fracture model and dual porosity-dual permeability model are used to simulate this problem. Governing equations for such reservoirs are conservation of mass and conservation of momentum. Evaluations are performed in two seperate parts. in the first part, geometry, boundary conditions and initial conditions which important models of transfer functions were calculated are provided by using discrete fracture model and results are compared with results of corresponding reference. Following... 

Hydrocarbon recovery projects involve large capital investments and have a very high risk associated with them. To minimize this risk, accurate predictions of reservoir performance must be acquired. Reservoir simulation is a powerful tool for fulfilling this requirement. Physics, mathematics, reservoir engineering and computer programming are combined in reservoir simulation in order to predict reservoir performance under different situations both accurately and efficiently. Performance prediction in fractured reservoirs is a much harder task. This difficulty is due to the higher uncertainties associated with their physical and geometrical parameters. More than 60% of world, and almost 70%... 

At today’s crowded world, the importance of automobile transportation is obvious for all. Due to energy crisis and air pollution problems, designing and manufacturing high-performance and low emission engines is very important. Because of high efficiency and low fuel consumption, diesel engines have attracted more attention. In addition to the mentioned advantages, diesel engine’s nitrogen oxide and particulate matter emissions are very high. So to limit these pollutants, strict standards was legislated by different countries and nations. Recently in the field of diesel engines emission reduction, low temperature combustion concept is proposed that can reduce nitrogen oxide and particulate... 

In this thesis, two types of two-phase flow are studied in one dimension. The first type is oil-gas two-phase flow which is miscible and compressible. The second one is oil-water two-phase flow which is immiscible and incompressible. Oil wet and water wet conditions are studied in the second type of flow. Two approaches, i.e. double porosity and double porosity-double permeability, are used to study naturally fractured reservoirs. In these approaches, the matrix and fracture are modeled as two separate media that exchange mass via a transfer function. Black oil model is applied to simulate the fluid system. The governing equations consist of the conservation of mass equations for each... 

The gas flow field geometry influences the transport phenomena inside PEMFCs and hence affecting their overall performance. Radial force and secondary flows resulting from curvature of the spiral channels in PEMFCs can improve mass transport limits and so does to their overall performance. Studying the effects of curvature of spiral channels on fuel cell performance and comparing them with similar designs is the aim of this thesis. The geometries are generated using concentric Archimedes’ spirals and categorized as axial or radial depending on the direction of the vector perpendicular to their MEA . Each category has five geometries which are the result of branching the main channel into...