Sharif Digital Repository

A 3-D CFD model was developed to study effects of early/late intake valves opening/closing on flow field characteristics in the Intake Manifold (IM) of a spark-ignited gasoline 1.5 Litre, 4-cylinder engine. The main task of IM is to prepare essential air for combustion process into cylinder which should distribute air to total runners of IM properly. In this modeling, combustion process and valve behaviors and how to pass fluid flows through intake valves are simulated separately and they are added to it.HyperMesh, Fluent, GT-Power, and MATLAB were used to create a mathematical model on the geometries of IM in TIBA engine, one National Engine of Iran, obtained from MEGA motor Company. The... 

Hydraulic fracturing is a process during which a viscous fluid under relatively high pressure and flow rate is injected into a wellbore to induce and propagate a system of cracks in the ground.Hydraulic fracturing of underground formations has been widely used in different fields of
engineering, such as petroleum engineering, geotechnical engineering, environmental engineering, mining engineering,and so on.Despite the technological advances in the techniques of in-situ hydraulic fracturing, the industry lacks a realistic and reliable numerical model to design cost - effective and efficient hydraulic fracturing treatment.This is due to the complex interaction and strong coupling between... 

Researchers have done a lot of studies about the use of CFS in blood flow modeling in order to improve the supplementary devices or find mechanical factors which cause artery to be diseased. Blood is a complex rheological fluid, blood flow is a pulastile flow, and blood flow field interacts with the deformable vessel wall. Thus, blood flow modeling like other biological phenomena has its own complexities such as anisotropy, vsicoelasticity, and nonlinearity in stress-strain relationship of vessel wall. To explore the role of hemodynamics in the initiation and progression of stenosis in carotid artery bifurcation, a 3D Computational Fluid Dynamics (CFD) technique is applied. The effect of... 

This dissertation discusses the development of dimensionless correlations for predicting hydrodynamic parameters and CFD simulation of gas-solid two phase flow in conical fluidized beds. This research mainly focuses on the impact of particle size distribution on hydrodynamic parameters. The first section describes the experiments that were carried out with a number of gas–solid systems in a conical column to study certain important characteristics of the fluidized bed. Generalized empirical correlations, based on dimensionless analysis, have been developed in order to predict minimum fluidization velocity, minimum velocity of full fluidization, maximum pressure drop and bed expansion ratios.... 

Flows in porous media exist in many practical and research fields including water flow in soil, transport of pollution in soil, oil recovery engineering, and etc. Studying the multi-phase flows seems being too complex due to the interactions between fluids or between fluid and media in the porous media, wetting tendency of fluids, intrinsic permeability of the porous media, tortuosity of the flow’s path and etc. Hence, the field and laboratory studies of multi-phase flows is difficult, if not impossible. While numerical methods can handle many of these complexities, many of them are unable to simulate the micro-scale flows. On contrary, Lattice Boltzmann has no such shortcomings and even is... 

Greenhouse gas emissions into the atmosphere have multiplied with the increase in fossil fuel consumption, which directly affects global warming. Global warming has other undesirable consequences such as rising sea water level and declining snow cover. To reduce greenhouse gases in the atmosphere, researchers have studied various ways, one of which is carbon dioxide injection into underground formations, which has a significant effect on reducing the amount of these gases in the atmosphere. Existence of high volume underground reservoirs with suitable conditions for gas injection to prevent gas escape has made it a widely used and effective method. Despite many advantages of this method, it... 

Transport phenomena in porous media play important role in many areas of subsurface hydrology, geo-physics, environment, energy and petroleum. The work in the field of numerical modeling of fractured porous media is yet an open area of research. The classic finite element method (FEM) has some limitations in modeling of discontinuities like fracture. FEM mesh should conform with the geometry of the fracture. Presence of fracture imposes discontinuity in pressure field of fluid phases and displacement field of solid phase (rock). To represent the fractures, the extended finite element method (X-FEM) can be used in which the standard finite element approximation of the field variables is... 

Low salinity water injection is one of the new and important methods of enhancing oil recovery. Experimental studies show the fact that the change in water salinity affects the interfacial properties of water-oil (Fluid-fluid interactions) And the change in wettability that represents the porous media (Rock-fluid interactions) is effective for Oil-recovery. Recently, progress have been made in simulating the process of injecting low-salinity water into the field or core dimensions. However, the simulation of the low salinity water injection process has been much less studied considering the fluid / fluid and fluid / rock interactions at the pore scale. The purpose of this study is to...