Sharif Digital Repository

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... 

Sedimentation tanks are channels designed for sedimentation of suspended solids in water. These tanks are one of the most important parts of water treatment plants and their performance directly affects the functionality of water treatment plants. Therefore, researchers have tried to find better designs of sedimentation tanks. Among several design methods have been presented, modification of the geometry of tanks by installing baffles is one of the most effective and economic methods. According to the importance of performance improvement of industrial sedimentation tanks as well as the diversity in reported results, development and completion of previous studies seem to be necessary. In... 

This thesis introduces a fast and accurate two-phase reservoir flow simulation procedure. The speed up is achieved by an upscaling technique where coarsening is applied to the detailed geological reservoir descriptions. This process results to two major error sources affecting the simulation accuracy significantly. The homogenization error is appeared when coarse scale data, such as equivalent permeability, is calculated from the available fine grid model information. It is shown that the error can be reduced adjusting coarse grid (non-uniform Cartesian) distribution. For the first time in this study, the grid distribution optimization is done based on “vorticity” map. In particular, the... 

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,... 

Bubble formation and bubble rising are widely used in many industrial processes such as bubble columns, extraction, fermentation, foaming and polymerization. Although many of these processes are faced with a series of bubbles, this study may help us better understand the hydrodynamics of single bubble formation and bubble rising and provides a deep insight into the modeling of a series of bubbles. Bubble velocity and drag coefficient in various fluids are the major parameters for designing the liquid-gas systems. These parameters are a function of the bubble size. In this study, single bubble formation is theoretically modelled in order to predict the size of the bubble at the moment of... 

In this study, DREAM model operation as a model to predict the occurrence of dust storms has been completed. The aim of this study is to identify capability of the model to predict dust storms in IRAN. The model has been run for June 2014 because on 2 June 2014, Tehran visited a dust storm with a speed of 111 kilometers per hour and yielded a huge economic losse. In this model, dust concentration,dust load and Aerosol Optical Depth(AOD) are calculated on an hourly basis. The model results do not captured the direct relationship between the average wind speed and dust Parameters and the model do not predict the dust storm on on 2 June 2014 in Tehran. The reason is that DREAM gets... 

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...