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firoozabadi--bahar
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Total 87 records
Continuum Modeling of Biological Growth of Atheroma in Coronary
, M.Sc. Thesis Sharif University of Technology ; Firoozabadi, Bahar (Supervisor)
Abstract
Atherosclerosis is a vascular disorder caused by inflammation of the arterial wall. This inflammation leads to the accumulations of low-density lipoprotein (LDL) cholesterol, monocytes, macrophages and fat-laden foam cells at the site of inflammation, often referred to as plaque formation. This work uses a mathematical model for simulating the deposition of atheroma plaque in coronary arteries. In this study, the effect of time average wall shear stress (TAWSS), oscillatory shear index (OSI), non-Newtonian characteristics of blood and variable hematocrit values on the occurrence of atherosclerosis in a three-dimensional coronary artery was numerically investigated. Simulations was conducted...
Modeling and Forecasting Dust Storms in Yazd Province
, Ph.D. Dissertation Sharif University of Technology ; Firoozabadi, Bahar (Supervisor) ; Afshin, Hossein (Co-Supervisor)
Abstract
The Yazd province is located in the dry and desert region of Iran and is constantly exposed to strong winds and dust storms due to its climatic conditions and geographical location. The first objective of this thesis is to assess the dust storm events that have occurred in Yazd province in order to identify their source and pathways of transport during the long-term period of 2012-2019. A novel multi-criteria framework for identifying the sources of dust storms and dust events in Yazd province has been presented using the HYSPLIT model. In this framework, the numerical results, along with geographical features, observational and satellite data, were used as criteria in the multi-criteria...
Numerical Study of Vascular Shear Stress Effects on Blood Clotting Processes
, M.Sc. Thesis Sharif University of Technology ; Firoozabadi, Bahar (Supervisor)
Abstract
Blood clotting and clot formation in damaged vessels are vital mechanisms of the body. Any disorder in performing this mechanism leads to various problems such as excessive bleeding or, on the contrary, causes vascular occlusion and diseases such as embolism. Due to the importance of this issue, extensive research has been done to understand this phenomenon and the factors affecting it. In this thesis, the effect of shear stress, coagulation factor concentration and wound location in coronary bifurcation on clot formation and growth and its interaction with velocity field is numerically investigated. Blood flow is modeled non-Newtonian with Carreau-Yasuda model. Various chemical species...
Numerical and Experimental Modeling of the Thermal-Saline Jet Discharge from : Thermal-Saline Jet Water Desalination Plants and Providing a Practical Solution to Reduce its Environmental Impacts
, Ph.D. Dissertation Sharif University of Technology ; Firoozabadi, Bahar (Supervisor)
Abstract
More than 80% of desalination units in the Persian Gulf use multi-stage flash (MSF) technology. The discharge of effluent from these units sometimes causes severe impacts to the marine environment due to the increase in temperature and salinity around the discharge point. In the current thesis, the geometrical, mixing and turbulence characteristics of the discharge of thermal-saline inclined jets under the water surface, similar to the effluent of MSF units, are numerically investigated by developing the buoyantBoussinesqPimpleFoam solver in the OpenFoam open-source software, using the LES turbulence model and the dynamic Smagorinsky subgrid scale and the UNESCO equation of state. The...
Numerical Investigation of Hypertension in Plaque Formation and Growth in Human Aorta
, M.Sc. Thesis Sharif University of Technology ; Firoozabadi, Bahar (Supervisor)
Abstract
Nowadays, cardiovascular diseases are among the most prevalent cause of death worldwide. Besides, atherosclerosis is a cardiovascular disease happening with the continuous narrowing of vessels, especially medium and large-sized arteries. Moreover, the human aorta is vulnerable to this phenomenon. Atherosclerosis happens when the excess LDL in the blood flow penetrates the arterial wall. Then, the LDL is oxidized, thereby recruiting monocytes as the response against oxidized LDL. After monocytes enter the arterial wall, they differentiate and become macrophages. Macrophages then transform into foam cells by ingesting the oxidized LDL. The fatty foam cells are eventually responsible for the...
Development and Assessment of a Numerical Model for Investigation of Regional Dust Distribution
, Ph.D. Dissertation Sharif University of Technology ; Afshin, Hossein (Supervisor) ; Firoozabadi, Bahar (Co-Supervisor)
Abstract
In recent years, dust storms have been recognized as one of the most crucial problems for people worldwide. Provided that the dust masses transport mechanisms are properly known, the main dust sources can be identified, and therefore, appropriate actions can be taken. Therefore, the main goals of the present study are estimating dust concentration, determination of dust distribution with an emphasis on Iran (especially Tehran), and finding the main dust sources which will be followed in five steps. In the first step, by analyzing the measured data during dust observations in Tehran through 2013-2016, several simple and multivariate nonlinear regression models have been established in order...
Multi-scale Simulation of Tumor Microenvironment
, M.Sc. Thesis Sharif University of Technology ; Firoozabadi, Bahar (Supervisor) ; Mozafari, Ali Asghar (Co-Supervisor)
Abstract
Search for effective methods for treating cancer requires a deep understanding of the tumor microenvironment and its role in cancerous tumor growth and progression. Mathematical modeling methods, which have fewer limitations than experimental methods for examining the microcirculation of cancer in detail, are suggested to answer many questions about the behavior and dynamics of cancerous tumors. In the present study, a multi-scale mathematical model of the three-dimensional tumor microenvironment, including molecular, cellular, and tissue scales, is presented. In this model, important aspects of tumor microenvironmental dynamics including tumor growth, angiogenesis, cancer metabolism, and...
Numerical Investigation of the Seabed Inclination Effects on Mixing Characteristics of the Brine Discharged Jet from Desalination Plants
, M.Sc. Thesis Sharif University of Technology ; Firoozabadi, Bahar (Supervisor)
Abstract
A large number of desalination plants have been established to overcome the drinkable water scarcity in the world. These plants produce saline water as effluent, which is often discharged into local sea water. One of the applicable methods to dispose these kinds of effluents is to install an inclined nozzle below the water’s surface. Hence, an inclined negatively buoyant jet (INBJ) forms which is often fully turbulent due to the high discharge velocity. Local environmental characteristics affect the dynamics and mixing behavior of INBJs. One of these characteristics is the sea bed slope, on which the present study has been focused. Large eddy simulations (LES) are performed in the present...
Simulation of NO Production Process from Endothelial Cells and its Effect on Coronary Artery Flow Field
, M.Sc. Thesis Sharif University of Technology ; Firoozabadi, Bahar (Supervisor)
Abstract
Endothelial derived nitric oxide (NO) and its role in regulating the physiological conditions of blood vessels is one of the favorite topics among researchers. The majority of previous studies have focused on nitric oxide transport in blood vessels, less attention has been paid to its vasodilative effects in blood vessels. The main aim of this study is to propose an integrated model to study the effects of endothelial-derived nitric oxide on hemodynamic conditions of blood vessels. Nitric oxide is produced by endothelial cells upon exposure to mechanical forces such as hemodynamic shear stress. The synthesized nitric oxide then diffuses into the neighboring vascular smooth cells, where it...
Pulsating Pulmonary Blood Inflow in Total Cavopulmonary Connection (TCPC) after Fontan Surgery
, M.Sc. Thesis Sharif University of Technology ; Sayadi, Hassan (Supervisor) ; Firoozabadi, Bahar (Supervisor) ; Navabi Shirazi, Mohammad Ali (Co-Supervisor) ; Malakan Rad, Elaheh (Co-Supervisor)
Abstract
Patients with a single ventricle disease who have undergone Fontan surgery have always had long-term complications. These complications include pulmonary artery stiffness and decreased ability to exercise. In fact, due to removal of the right ventricle from the circulatory system, blood pressure and pulsatility inflow to total cavopulmonary connection (TCPC) are reduced following this surgery. Creating waves (radial displacement) on the IVC (Inferior Vena Cava) wall can increase pulmonary flow pulsations. The Objective of this study is to test the effect of induced wave amplitude on the pulmonary flow pulsations at the rest condition. Computational fluid dynamic (CFD) simulations were...
Investigation of the Influence of Meteorology-Chemistry Interaction on the Results of Air Quality Modeling During a Highly Polluted Episode in Tehran
, M.Sc. Thesis Sharif University of Technology ; Firoozabadi, Bahar (Supervisor) ; Hosseini, Vahid (Supervisor)
Abstract
Atmospheric aerosols scatter or absorb a fraction of the incoming solar radiation to cool or warm the atmosphere, decreasing surface temperature and altering atmospheric stability to further affect the dispersion of air pollutants in the planetary boundary layer. This study aims to evaluate the impacts of meteorology-chemistry interaction on the meteorology and air quality simulations over Tehran megacity. The Coupled Weather Research and Forecasting-Community Multiscale Air Quality (WRF-CMAQ) modeling system was applied to model a period of time from 3rd to 23rd December of 2017. Comprehensive model evaluations for meteorology demonstrated that the modeling system had the capacity to...
Simulation of the Influence of Hypertension on Low Density Lipoprotein (Ldl) Permeation into Multilayer Coronary Bifurcation
, M.Sc. Thesis Sharif University of Technology ; Firoozabadi, Bahar (Supervisor)
Abstract
Atherosclerosis, due to the penetration of low-density lipoprotein particles (LDL) into the arterial wall, is one of the most common and death-leading diseases in today's world. Due to its importance, extensive research has been conducted on the factors that affect this disease. In this thesis, a numerical study of the effects of Wall Shear Stress (WSS), non-Newtonian behavior of blood, different hematocrit values, and blood pressure on LDL permeation through the artery wall layers are investigated in a 4-layer wall model of a coronary bifurcation. To obtain the velocity and concentration fields in the domain, momentum, Brinkman, and mass transport equations are solved in the lumen and wall...
Numerical and Experimental Study of the Effects of Surfactant on Droplet Motion and Deformation
, Ph.D. Dissertation Sharif University of Technology ; Firoozabadi, Bahar (Supervisor) ; Afshin, Hossein (Supervisor)
Abstract
Surface Active Agents/surfactant have a strong tendency to adsorb at the interface between two immiscible fluids, due to the existence of hydrophobic portions in their molecules’ structure. Accumulation of these molecules on the liquid interface changes the intermolecular forces and causes the interfacial tension to decrease. Production of drops of the same size at a specified rate and controlling their movement’s speed are among the most important factors effective in the efficiency of processes associated with liquid drops, which could profoundly be influenced by the presence of a small amount of a surface active agent. In this study, the effects of surface active agents on the growth,...
Numerical Modeling of Treatment of Liver Tissue Cancer by Using High Intensity Focused Ultrasound (Hifu)
, Ph.D. Dissertation Sharif University of Technology ; Firoozabadi, Bahar (Supervisor)
Abstract
In recent years, the incidence rate of liver cancer has increased sharply and nowadays liver cancer is known as the second leading cause of cancer death in the world. Surgical resection is usually used to treat malignant hepatic tumors. However, in some cases, surgical resection is not possible because of some reasons, such as tumor size and location. In these cases, other minimally invasive ablation methods such as radio-frequency ablation, microwave ablation, and high intensity focused ultrasound (HIFU) can be used. HIFU has some advantages such as noninvasiveness, high penetration depth, and low cost in comparison to the other ablation techniques such as radiofrequency ablation. In HIFU...
Control of Blood Flow by Endothelial-Secreted Biochemicals NO, Ca2+ and Growth Factor VEGF: Numerical Simulation Using Lattice Boltzmann-Finite Difference Hybrid
, M.Sc. Thesis Sharif University of Technology ; Firoozabadi, Bahar (Supervisor)
Abstract
Endothelial cells that cover the inner wall of blood cells and are sensitive to receiving mechanical signals play important role in regulating many vital activities of the human body especially the function of the cardiovascular system. One of the factors affecting the mechanical functions of these cells is the shear stress applied to them. Due to blood velocity increasing or decreasing the endothelial cells shear stress change and leads to some chemical reactions and finally releasing biochemical substances including Nitrogen-Monoxide and Calcium-ion. Nitrogen-Monoxide produced by endothelial cells by affecting the smooth muscle cells in the vessel wall causes dilating of the vessel wall,...
Investigation of the Depth Effects on Desalination Plants Turbulent Dense Jet Discharge Propagation by Large Eddy Simulation
, M.Sc. Thesis Sharif University of Technology ; Firoozabadi, Bahar (Supervisor) ; Kazemzadeh Hanani, Siamak (Supervisor)
Abstract
The scarcity of potable water is one of the world's challenges. In the Middle East, this crisis is even worse and as a consequence, the most aggregation of desalination plants has been constructed in this area. However, brine effluent discharged from these plants entails serious environmental issues. Despite the extensive studies about the investigation of dilution and the area which faces the brine discharges as submerge jets, there are a few experimental investigations with a focus on the injecting brine discharge into the shallow environment. Whereas the Persian Gulf's coastal environment is shallow. Moreover, there is a huge construction of desalination held in this area. Accordingly,...
Effects of Heart Dynamic Motion on Blood Hemodynamics and LDL Accumulation in Coronary Bifurcation
, M.Sc. Thesis Sharif University of Technology ; Firoozabadi, Bahar (Supervisor)
Abstract
In this thesis, the effect of heart dynamic motion and pulsatile inflow on blood hemodynamics and LDL permeation into the arterial wall in a 3-D coronary artery bifurcation was investigated. To determine the effect of each factor alone and simultaneous effect of both factors i.e. heart dynamic motion and pulsatile inflow, flow simulations were performed in four cases i.e. steady-static, steady-dynamic, pulsatile-static, and pulsatile-dynamic. The results of flow simulations showed that dynamic geometry and pulsatile inflow have considerable impact on temporal variations of wall shear stress (WSS), even though the effect of pulsatile inflow on WSS variation dominates over the effect of...
Simulation of LAD-LCX Bifurcation Hemodynamics of Coronary Artery Disease to Design an Effective Bypass Graft
, M.Sc. Thesis Sharif University of Technology ; Firoozabadi, Bahar (Supervisor) ; Afshin, Hossein (Supervisor) ; Pakravan, Hossein Ali (Co-Supervisor)
Abstract
In this study, three recent predictors of severity of coronary stenosis including fractional flow reserve (FFR), instantaneous wave free-ratio (iFR) and coronary flow reserve (CFR), are calculated for a number of patient-specific models of left coronary arteries. These patients are admitted to Tehran heart center. The main aim is presenting the optimum numerical and clinical detection technique to assess the severity of coronary stenosis. The effect of geometric features of stenosis is studied on the results of the FFR, iFR, and CFR in order to determine their accuracy. It is observed that CFR does not have a good estimate of the amount of disease. But, iFR, as a less risky test than FFR,...
Experimental Investigation of Surfactant Effects on Drop Formation of Shear-thinning Liquids
, M.Sc. Thesis Sharif University of Technology ; Firoozabadi, Bahar (Supervisor) ; Afshin, Hossein (Supervisor)
Abstract
In this research, the characteristics of non-Newtonian, shear-thinning drop formation containing surfactant from a needle are investigated experimentally. The ambient fluid is air and all experiments have been conducted in a constant flow rate of drop phase fluid. Images of forming drop are taken using a high-speed camera and by processing them, important parameters in drop formation such as length of drop, minimum neck thickness, formation time and the size of satellite drops have been studied. Three non-Newtonian and three Newtonian fluids are considered in a way that the initial viscosity of non-Newtonian fluids would be equal to the viscosity of their corresponding Newtonian fluids....
Theoretical and Experimental Simulation of Hepatic Cells and their Functionalities On-a-chip
, Ph.D. Dissertation Sharif University of Technology ; Firoozabadi, Bahar (Supervisor) ; Firoozbakhsh, Keikhosrow (Supervisor)
Abstract
Liver is the largest internal organ of the human body which serves many vital functionalities. Recently, liver-on-a-chip systems have been used to model some of the vital liver specific-functions and to investigate its related diseases. The purpose of the present study was simulation of some of these liver specific functionalities on-a-chip and using the obtained results in predicting hepatocellular functionalities i.e. production of some metabolites and modeling some of the liver-related diseases which have been done numerically and experimentally. Numerical simulations have been developed in two-dimensional and three-dimensional forms. In the 2D simulation, the governing equations i.e....