Sharif Digital Repository

Unglazed Transpired Solar Collectors, recently called "Solar Wall", are known as the most efficient solar air heating system for the past two decades. The equator faced collector which is installed in this system has many tiny perforations to suck in the air with a fan and gain the absorbed heat by the collector. Convection and Radiation heat losses from the absorber to surrounding and other design factors have different influents to the heat gain of this system. In this study, Continuity, Momentum and Energy equations are written with proper boundary conditions, solved with computational fluid dynamics methods and validated in order to model Solar Wall system. Thus we could compare all... 

The Curing of thick thermoset parts of composites Experience substantial temperature overshoot, especially at the center of those thick parts and large temperature gradient exists through the whole part due to large amount of released heat, thickness and low conductivity of the composite.this leads to non-uniformity of cure, residual stress and consequently composite cracks and possibly degradation of the polymer. In this thesis, first a thick cubic geometery of glass/epoxy composite is modeled with the help ofa commercial CFd packageand sensitivity to different effective parameters of this process is investigated with the help of this model.This model is then substituted by a trained... 

In recent years, unmanned vehicles have intensively been developed to reduce human dangers for marine applications. Predicting the hydrodynamic coefficients of an autonomous underwater vehicle is important during the vehicle’s design phase. In other words to design an AUV, one must clarify its maneuverability and controllability based on a mathematical model. The mathematical model contains various hydrodynamic forces and moments expressed collectively in terms of hydrodynamic coefficients. Therefore, the correct values of the coefficients must be known to precisely design the controller of AUVs. SUT-2 is an AUV, being developed by Marine Engineering Laboratory of Sharif University of... 

Different modeling and simulation techniques, new numerical methods and analyzing effects of different parameters on operation of bubble columns are continuously under study for optimized design, scale-up and prediction of industrial bubble columns. Tools for analyzing and developing gas-liquid systems are experimental techniques and computational fluid dynamics (CFD). In order to describe accurately the fluid dynamics of complex gas-liquid systems, more advanced mathematical models are required. To obtain a feasible numerical solution, efficient numerical techniques must be devised. One of such models that considerably reduces the assumptions and consequently increases the accuracy of... 

In recent years, many advanced Computational Fluid Dynamics (CFD) methods have been developed for accurate and efficient simulation of fluid flow. The application of these methods shows that for sufficient accuracy, the mesh resolution has to be reasonably high. Unfortunately, conventioanal single-grid Navier-Stokes solvers suffer from poor convergence characteristics. For this problem we used Multigrid method to speed up the convergence rate. In this section a code was developed (based on the conventional CFD algorithm) which can solve Navier-Stokes equations on structured grids. It also simulates the free surface by VOF method. Agglomeration multigrid method is used in present study for... 

In this thesis heat transfer coefficient and temperature distribution of two Non-Newtonian and a Newtonian fluids in stirred vessel are investigated using Computational Fluid Dynamic (CFD). This vessel is agitated with new impeller called MAXBLEND. Non-Newtonian fluids are aqueous solutions of carboxymethyl cellulose 1.5%w/w and xanthan gum 3% w/w and Newtonian fluid is glycerin. This vessel is simulated in laminar regime with Reynolds number less than 14. The results of simulation are compared with correlation proposed by Kawase et al. Furthermore as a new research for this impeller, the effects of vessel diameter and position of impeller in the vessel on heat transfer coefficient are... 

Vortex Tube is a mechanical device without any moving parts. It separates a compressed gas stream into a low and a high temperature region (temperature or energy separation effect). Advantages of VT are existence of no moving parts, no external power (electricity or flames) required to operate, tiny and lightweight, inexpensive tube & parts material, convenience and pollution free. Heating, cooling, cleaning and drying gases, separating gas mixtures, gas liquefaction, natural gas pressure reduction and dehydration are the applications of vortex tube. The main Objectives in this research are investigation of various types of gas streams including pure gas or mixture of gases in vortex tube... 

Wide range application of high speed marine crafts in marine industry and other related industries results in attempts to improve the performance of such vessels. The main ideas of using control surfaces in high speed planing crafts are the change of the high speed planing craft‘s resistance due to change of their running attitudes and wave response mitigation of this vessels. Control surfaces produce forces and a pitching moment due to a pressure distribution caused by them, which can be used to alter the running attitude of high speed marine crafts. The present work contains a comprehensive study on trim tab as a control surface for the high speed crafts. The results of this study condense... 

A steady laminar flow coupled with heat transfer and chemical reaction corresponding to metalorganic chemical vapor deposition (MOCVD) in an axis-symmetrical rotating disc reactor has been simulated in a detail manner based on Computational Fluid Dynamics approach. The simulation results have been validated with the benchmark solutions obtained from the literatures for the corresponding casestudy.Three decision variables have been used whose optimum values are sought inorder to minimize the nonuniformity of the film on the susceptor. Their optimum values have been obtained by the elder-Mead algorithm which is a geometric optimization method which does not require gradient of the objective... 

Brine in crude oil causes many problems that underpin the importance of its separation. In recent years brine in crude oil has been increased with increase of the oil fields lifetime and its separation has been more important. One of the most effective separation methods is electrocoalescence. In this research, the simulation of brine droplets motion and their coalescence under the effect of electric field have been investigated by using the Computational Fluid Dynamics method and the droplets size distribution has been calculated under different values of electric field magnitude. The motion of two single brine droplets in stagnant oil phase and the behavior of many numbers of droplets in... 

Based on progress madein industry, considering the essence of human resource health is an inevitable subject. Ventilation is an important matter which affects the quality and efficiency of production due to its coherence with providing a healthy and suitable workplace. In this regard, there are some settings for industrial ventilation systems which are designed to satisfy related health and hygiene standards.Simulation of ventilation systems based on CFD methods is a great contribution to choose anappropriate ventilation system type. In this study, by modeling the proposed ventilation setting in a 3D environment, we are assured that the system is capable of industrial ventilation in welding... 

Recently, many investigations are done in the field of the modeling of the cardiovascular system. For the purpose of understanding of this system, mainly the location of formation and development of atherosclerosis, these investigations are so vital. The multi-scale modeling is an appropriate method to reduce the cost of calculation and also, this method simplifies the complicated model of cardiovascular system. This research presents a multi-scale 1D-3D modeling of cardiovascular system. In this model, the three dimensional geometry of carotid bifurcation is coupled with a one dimensional full model of cardiovascular system. We used some user defined function in the Fluent software for... 

Among probable hazards in chemical industries: vapor cloud explosion (VCE) is one of the worst and most destructive ones. More than half of the major process inci¬dents, according to the statistics, are VCEs. VCE causes the most serious consequences; therefore, it attracts many attentions to itself. Accordingly, plenty of researches have been done for the purpose of protection against VCE effects. All efforts in this field can be categorized in two different main activities; firstly, prescribing safety distances between groups of hazardous equipment and vulnerable areas, secondly, using facilities which reinforce vulnerable areas against explosion blasts. Regardless to which category is... 

Gas leak explosion is major risks in closed environment in the chemical industry. One of the fundamental principles of safety is control of ignition sources using special protective equipment in areas where possible flammable gases or vapors are there. Computational fluid dynamics is used in this project to evaluate and analyze the risks associated with gas distribution. Ventilation effect has been studied by computational fluid dynamics on gas cloud formed by leakage of flammable in hazardous areas. To demonstrate the accuracy of calculations performed by computational fluid dynamics, the results are validated by experimental data. The simulated results for gas dispersion are found to be in... 

In the present study, performance of a novel fan namely bladeless fan has been evaluated. The aerodynamic and aeroacoustic performances are studied by using 3D simulation of this fan. Mass conservation equation, momentum conservation equations and noise equations of FfowcsWilliams-Hawkings numerically solved to investigate performance of this fan. Firstly, fan cross section profile was designed by Eppler airfoil 473 instead of the prior profile as a modification then effect of different geometrical parameters on the performance is examined. These parameters are height of cross section, angle of output flow with respect to fan axis, thickness of output airflow, hydraulic diameter and aspect... 

The main objective of this research is to experimentally evaluate thermal behavior of commercially available rechargeable Li-ion batteries based on minimum measurements on main battery parameters and then develop experimental based models to investigate their thermal behavior. Li-ion batteries with Graphit anodes and Li(Ni0.8¬Co0.15Al0.05)O2 cathodes will be used for this purpose. Voltage and temperature developments during cycling under various currents at controlled ambient temperatures are measured by battery tester. Measurements show that temperature evolutions demonstrate falls and rises at specific State-of-Charge (SoC) of the battery during cycling and therefore some heat consumers... 

The release of toxic materials causes tragic accidents every year. There are various techniques in order to mitigate the release effect of these materials such as Application of air jets, steam curtains and water curtains. In this study first, previous works are reviewed in order to select the best technique for the mitigation of heavy toxic gas release. Then CFD modeling is used to simulate this technique.
A field situation in which chlorine gas was released upwind of water spray was simulated using the open-source software FDS (Fire Dynamic Simulator), a CFD model. Only mechanical effects of water sprays are considered; hence the effect of absorbtion is neglected. Finally tha...