Sharif Digital Repository

Today, the world energy crisis, the need to optimize its consumption and discussion to reduce fuel consumption has become a vital issue. The conventional vehicle air conditioning system due to compressor in refrigeration cycle, which has causes a severe loss in engine useful power, increasing fuel consumption, etc. Therefore, the main goal of this project is the feasibility of the vehicle cooler replacement with the vapor jet refrigeration cycle. In this cycle, the energy required for completing the refrigeration cycle is provided from the heat of the water inside the radiator that is possible with conventional refrigeration cycle. The first stage of this project includes design and... 

In this study numerical methods are used for modeling flow and simulation of aerosol transport and deposition in alveolar zone of human lung. The flow modeling is done by FLUENT code, using its moving boundaries feature. For particle tracking we developed a code that uses results of velocity field obtained by FLUENT code. Two-dimensional the axisymmetric model was investigated in this study, and was exhibited that rhythmically expanding walls in alveolar duct model has significant influence on flow patterns and particles transport mechanism. In this study we also developed a three-dimensional model of a single alveolated duct with moving boundaries allowing for the cyclic expansion and... 

Entrance of air to close water conduits occurs in many ways. This phenomenon makes displeasing effects on water transport structures. Two-phase flows in closed conduits are studied experimentally, numerically and theoretically. Even after decades, due to the complexity of the subject, these studies still require development and reformation. Numerical and theoretical two-phase models are often limited to a special regime of flow."Volume Of Fluid"(VOF) is a model for non-mixing two-phase flows. "Fluent" software uses this model in this field of flows. Volume of fluid is used successfully in some problems like dam break or rising bubbles. Main disadvantage of this model is distribution of the... 

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... 

Today, the world energy crisis, the need to optimize its consumption and discussion to reduce fuel consumption has become a vital issue. The conventional vehicle air conditioning system due to compressor in refrigeration cycle, which has causes a severe loss in engine useful power, increasing fuel consumption, etc. Therefore, the main goal of this project is the feasibility of the vehicle cooler replacement with the vapor jet refrigeration cycle. In this cycle, the energy required for completing the refrigeration cycle is provided from the heat of the water inside the radiator that is possible with conventional refrigeration cycle. The first stage of this project includes design and... 

This research concerns investigating the behavior of two-phase flow in the inlet and outlet of the microchannels.Both the droplet based and the continuous microfluidics are considered. For the continuous system whenthe minor fluid enters the microchannel, due to ratio of viscosity of two fluids, viscous folding occurs.Viscous folding phenomena is similar to the buckling phenomena in solids.This means that the viscosity of the fluid, which is applied to two sides of the fluid layer, causes folding the fluid layer and changing the shape of it. For the study we employ a VOF based numerical routine. In order to verify numerical results, the grid and the time step independenciesare checked. In... 

Future generation ships will be powered by highly efficient contra rotating propellers propulsion systems. The research presented in this thesis leads to a thorough understanding of Contra Rotating Propellers performance.At first tow propeller was detected. The propellers was drawing in Catia and simulated in Ansys Fluent.Also the propellers hydrodynamic forces was available in DTMB cavitation tunnel. Also a model of propellers was tested in Sharif University of Technology cavitation tunnel. Experimental results were obtained for the forces and torques on the propellers over a range of advanced coefficient. The velocities were measured in the field in near the propellers.The results of... 

Recent investigations on organs-on-chip devices have broadened our insight into the functions of the organs and their responses to pharmaceuticals. Studies on improving the efficiency of these chips are on going. The development of chips for growing various organs and possibly their possible interconnection are other hot topics in this field. This research is an attempt to simulate a Lung-on-a-Chip (LOC) device using Ansys Fluent software. Currently a new experimental technique for setting up a lung-on-a-chip device has been made public (Zamprogno et.al.ˏ̎ Second-generation lung-on-a-Chip with an array of stretchable alveoli made with a biological memvrane ̎ ˏComm. Biologyˏ2021ˏ4:168.). This... 

This thesis is concerned with modeling of air flow through upper airways of the human lung. Mechanisms of fresh (high Oxygen density) air transportation toward deep lung airways and Alveoli and reverse transport of dirty (low Oxygen density) air to upper airways of lung and moth, particle transport and deposition process, parameters affecting the simulation of flow like: steady and transient simulation, type of geometry including planar and non-planar, structured and unstructured network of airways, respiration pattern and real cycle of inspiration and expiration, inspection of expiration cycle on particle absorption efficiency and other effective parameters in deposition of particles in... 

A Lab-On-a-Chip (LOC) is a device which can integrate one or many laboratory functions on a small chip with millimeters to few square centimeters in size. LOC is a subset of MEMS devices and known as “Micro Total Analysis Systems” (µTAS) as well. LOC technology is closely related to microfluidics which primarily describes the physics, manipulation and study of minute amount of fluids.In this research we tried to simulate the performance of a microfluidic device for counting blood cells to find main factors of it for design and manufacturing. This research has two main sections, hydrodynamics of fluid inside the microchannels and finding electrical performance of designed Coulter counter for... 

The aim of the present research is to investigate the combustion chamber cooling with vortex method in presence of kerosene and liquid oxygen as propellants. For this purpose, a part of oxidizer is entered into the cylindrical combustion chamber tangentially (from bottem of the chamber), and creates a vortex flow (outer vortex). With motion of created outer vortex along the wall and eventually hit its top wall (the head of the chamber), secondary vortex (inner vortex) occurs along the center line, with a downward direction (opposite to the primary vortex). The fuel and other part of the oxidizer injection is also carried in the head of chamber, so by mixing the fuel and oxidizer that happens... 

The most important issues in massive concrete structures such as concrete dams are the increase in temperature due to heat generated by the dam Hydration of cement in concrete. Internal restrains are created from thermal gradient between the surface and the interior of the structure. External restrains are created from connections between structures and foundation for obstruct the movement of concrete structures due to temperature change. External restrains and internal creates tensile stresses in the concrete considerable, which can lead to thermal cracks in the structure. To prevent or minimize the possibility of cracks are examined thermal studies for the design of reinforced concrete... 

As diseases of eye’s posterior segment has got widespread outbreak in the world, the selection of treatment is very important. Until now, intravitreal injecton has been the most common way of drug delivery to the posterior segment. Although this method is effective, halflife of some drugs in the vitreous cavity, especially those with low molecular weight, is just about some hours. Therefore, it is necessary to repeat injection in order to maintain drug concentration level of the posterior segment in the desired level. Intravitreal injection is invasive and may cause severe adverse effects such as vitreous hemorrhage, retinal detachment, endophthalmitis and cataract. In order to decrease the... 

Considering the importance of environmental issues and the limitation of fuel supplies in the world, car issues have become one of the most important debates of the day. The methods used to reduce fuel consumption and emissions of greenhouse gases are primarily aimed at changing vehicle structure to reduce drag. An external body shape has been developed to reduce drag forces over the years. Due to the existence of limitations in the actual conditions of the theory, such as the beauty and convenience production, other methods should be examined. In this study, the structure of superhydrophobic properties materials with the emphasis on innovation has been considered. In order to investigate... 

Coal has always been an unneglectable share of countries’ energy basket as the oldest known fuel. Concerning Iran’s rich coal mines, it plays a particular role in the country’s development programs. Mine Ventilation is one of the most vital issues in mining activities. While excavation activities might experience an overhaul phase, Ventilation must be operating nonstop. Since coal mines are gassy generally, mine ventilation design should include appropriate principles. U ventilation scheme is the most common ventilation scheme being used in longwall coal mines. While spontaneous combustion is less probable in the scheme in comparison by other schemes, methane accumulation in tailgate entries... 

Leakages in the transmission pipes include a large proportion of water loss. Scarcity of fresh water in one hand and high costs to compensate for drop in pressure and flow lines, on the other hand, detection and location of leaks have been important. This phenomenon can also cause a lot of damage to the urban contextures. This thesis considers the leakage in tubing buried in the soil by means of a floating robot. Since the rate of leakage, specifies the requirement to perform maintenances, In addition to finding the leakage, an overall estimate of the amount of leakage is desired.Since non-destructive leak detection is desired, the mechanical-magnetic sensor is designed. First, for the... 

In this thesis, by focusing on the hydraulics of three phase flow in vertical tubing to investigate asphaltene deposition problem, the solid particles behaviors in a turbulent flow is fully studied. Reasonable size distribution for particles (based on previous works and researches) was assumed and a model for 2 sections of a Marrat oil field well to evaluate their asphaltene deposition problem was developed. Three phase liquid-gas-solid flow in the well tubing was simulated. Asphaltene deposition profile on the well tubing, mean and maximum of the deposition rate and particle concentrations in the flow regime were calculated and compared with real field data. Better agreement with field data... 

The design of inlet ports for spark ignition internal combustion engines has a direct and well-known influence on performance and emissions as a result of changes in volumetric efficiency and fuel burn rate.The design of ports is becoming more critical as SI engines are developed further to meet increasingly stringent exhaust emissions legislations. Lately further emphasis has been placed on port design by the re-emergence of the direct injection gasoline engine.
Due to lean burning, combustion instability and increasing the cycle to cycle variations, in the direct injection engine, combustion charactersitics will be improved by increasing the tumble in-cylinder flow and the turbulence... 

The Fukushima accident is one of the reasons why the spent fuel pool (SFP) is an important safety element. The large amount of spent fuel inside the spent fuel pool has made it a source of hydrogen and radioactive material in the accident of any disturbance to pool cooling. Although the loss of spent fuel pool cooling system accident has a slow transient, it can lead to disasters if you ignore it. In this project, spent fuel pool of Bushehr Power Plant unit ‘I’ was simulated by Ansys Fluent and the natural circulation of fluids in the absence of cooling system was investigated. The distribution of water temperature in the pool was investigated for the worst possible spent fuel pool loading... 

Thermal penetration is one of the separation methods. In this process, due to the temperature difference, the concentration gradient in one of the gas or liquid phases in the resulting system and the relative separation of the components is possible. The column used for this work is the Classius-Dickel column. This column consists of two vertical plates, one warm and the other cold, spaced a short distance apart. Due to the temperature gradient, the gradient is deliberately created, which creates a concentration gradient in the column, so that the light component accumulates at the top of the column and the heavy component at the bottom of the column. The difference in concentration between...