Sharif Digital Repository

Many of gas condensate reservoirs, including rich gas and lean gas, face with fast well productivity decline. The origin of this problem is condense accumulation around the well bore which known as condensate blockage. There are different condensate blockage mitigation methods, one of which is acid fracturing that is suitable for tight carbonate reservoirs with low KH. Acid fracturing simulation is high difficult and have not been undertaken a study that can adopt with experimental and field test results, so researchers usually use practical method and many developed software in this area use correlation form laboratory data. However, the literature show that experimental results can just... 

Agriculture is one the most water consuming sections in the world and roughly 60% of water demand is dedicated for this purpose. A seawater greenhouse manages to combine fan and pad greenhouse with humidification-dehumidification desalination in order to achieve water production next to agriculture products using moister in air which was used for cooling. The most important aspect of a seawater greenhouse is the amount of produced water. Many research on the condenser type and materials have been conducted in order to achieve a better performance, suggesting the utilization of a low temperature water source for the condenser. In this research, using a thermodynamic correlations to model the... 

This study seeks to evaluate reliability of wind power density over Khouzestan province using WRF simulations. Based on 10 meter wind speed data extracted from eight synoptic stations over Khouzestan province, two different domains were selected in south and south-west of khouzestan as promising regions with strong wind speeds. WRF model were used to simulate atmospheric data during 2016 and over two selected regions with 2 kilometers grid spacing. Simulated data were verified with comparing to in-situ data via three parameters of RMSE, BIAS and correlation. Results indicate that model configuration had acceptable accuracy in simulating wind speed data. In this study, Monte Carlo... 

The objective of this project is numerical simulation of air flow and heat transfer between two horizontal concentric cylinders with rotation of inner cylinder and inertia of outer cylinder grooves on the inner cylinder. In this study, the air, meanwhile rotational motion by the inner cylinder will enter into the annular space between two cylinders with certain flow rate. It can be mentioned to cooling of power plant generators, Electric motors and rotating machines among usages of air flow between two cylinders. In this article the objective is calculation of pressure drop and Nusselt number, temperature distribution on the inner cylinder under conditions of constant temperature of... 

In recent years, due to fires in mines around the world, the need to study the dynamic behavior of fire to understand how it spreads and design an appropriate fire extinguishing system to reduce damage to people and underground facilities has been felt. Mine fires are usually caused by external sources such as cable connections, methane gas explosions, or coal self-ignition due to oxygen uptake and rising temperatures.In this research, using Fire Dynamic Simulator (FDS) software, after drawing the geometry of a coal tunnel corridor in progress and creating a fire model through pyrolysis of PVC, fire extinguishing was performed by nozzles. If the nozzle does not succeed in extinguishing the... 

In the present work, the numerical solution of 2D inviscid compressible Magneto-hydrodynamic flow is performed by using the spectral difference (SD) method on quadrilateral grids. In this numerical method, similar to the discontinuous Galerkin (DG) and spectral volume (SV) methods, the concept of the discontinuous and high-order local representations is used to achieve conservation property and high-order accuracy. In the SD method, the test function or the surface integral is not involved and thus it has a simpler formulation than the DG and SV methods. In this numerical method, two sets of structured points, namely unknown points and flux points, are defined in each cell to support the... 

Nowadays, the attempts to reduce fuel consumption, greenhouse gas emissions and atmospheric pollutants, and economic savings, besides alignment with new rules, have been become the top priorities in the marines industry. In order to satisfy these goals, many efforts have been undertaken, including the vessel's trim and draft optimization which has done both experimentally and numerically and also thrust system simulation, to set a logical link between the effects of trim and draft of the ship and the calculated value of the required thrust from simulation to be able to optimize the fuel consumption. In this method, the ship is considered at the specific draft and the trim in bow and stern... 

Safety against fire and its potential destructions is provided by detection, protection and ventilation methods. Knowledge on fire behavior such as ignition and propagation along with heat and smoke release is essential for implementing these methods. Having such deep information, the fire can be detected at the correct time and be controlled or suppressed, with its heat and smoke removed efficiently, so that rescue services will be enhanced and fatalities and damages will be reduced.Numerical simulation of fire requires deep understanding of multiple phenomena including turbulent flows, conductive, convective and radiative heat transfer, large buoyancy forces, chemical reactions and... 

Stress Absorbing Membrane Interlayer (SAMI) is a slightly thin layer made of bitumen and aggregate placed between a pavement with limited cracking and overlay in order to avoid reflective cracking in overlay. SAMI’s performance depends on many factors such as pavement layer’s materials and thickness and existing pavement’s condition. Numerical simulations are powerful tools to evaluate SAMI’s performance. Previous studies showed that construction of SAMI does not necessarily reduce reflective cracking. This research investigated the effect of different parameters on SAMI’s performance using numerical simulations. The focus of this study was on the performance of SAMIs used between asphalt... 

The emergence and development of E-commerce prompted many companies to reduce their cost by seeking new solutions that improve customer satisfaction level and product distribution. In this research, the coordination of a truck and a motorcycle is considered to utilize both vehicles' benefits. The mobile location of customers is another assumption in this research. Therefore, it is possible for customers to suggest different delivery times and locations. Based on the customer situation, there are three location modes which specify the accessibility. In this study, a mixed-integer linear programming model is presented to minimize service completion time. In addition, two metaheuristic... 

Autonomous Vehicles have received much consideration in different trends in recent two decades. Autonomous Vehicles refer to vehicles that can drive without a driver and perform all driving tasks automatically, so eliminating the driver's role can affect various aspects. In this research, the effects of Autonomous Vehicles on the improvement of the traffic condition is studied. To this end, freeway’s performance parameters including travel time and traffic speed at the time of a traffic accident in mixed traffic conditions have been simulated. Considering that the braking behavior, acceleration, and speed changes of the Autonomous Vehicle are effective on the evaluation parameters, five... 

One technique to reduce variance of output in comparing two or more systems via simulation is random number synchronization. the primary technique for achieving synchronization is to assign an independent seed to each random process and then use the same collection of seeds across all systems . Another way of synchronization in systems with limited customer population is to assign different seed to each customer (transaction) and then use the same collection of seeds across all systems. The main Question to be considered here is which of these methods of synchronization can better reduce variance of output in a queue with finite customer population  

The properties of 3 nm-diameter fluorinated silica nanoparticles with different coverage percent of CF3 groups as water and oil repellents were investigated at the water-rock and decane-rock interface using molecular dynamics simulation. Simulating a pore of rock in presence of water and decane molecules separately, resulted in liquid bridging for both of liquids. The density profiles of liquids in the pore clearly show several highly ordered layers packing of the molecules close to the rock surface. Distribution of liquid molecules around the nanoparticles is much influenced with increasing CF3 groups on the nanoparticle surface. Results show that adsorption of functionalized silica... 

The lubricating oil is commonly used to cool down the moving parts of turbine gas systems. In many applications, this oil is cooled down using a recirculating water circuit. The water is then cooled down using an air-cooled heat exchanger. Any deficiency in aerothermodynamic design of such heat exchanger would result in high temperature of gas turbine moving parts such as bearings. Obviously, this mal-performance has adverse effect on the lifetime of these parts and their maintanence aspects. Since the good performance of air-cooled heat exchanger has numerous advantages for the performance of related gas turbine unit, it is mandatory to design these heat exchangers in minimum sizes and... 

Understanding the flow of liquids and particularly water in nanochannels is important for scientific and technological applications, such as for filtration and drug delivery. In this study, we perform molecular dynamics simulations to investigate the transfer of single-file water molecules across straight or nonstraight single-walled carbon nanotubes (SWCNTs). In contrast with the macroscopic scenario, the nonstraight nanostructure can increase the water permeation. Remarkably, compared with the straight SWCNT, the nonstraight SWCNT with the minimal bending angle of 30° in the simulations can enhance the water transport up to 3.9 times. Also increasing length and diameter of carbon nanotubes... 

Developing new micro and nano devices, help us instruction micro and nano devices in very small scales. Also nano technology improved in recent decades especially in century 21th. These devices contained many important members, such as micro and nano filters, micro channels, sensors, and electrical chipsets. Navier-Stockes equations with slip and no-slip conditions can not used in transition and free molecular regimes. Since most of the MEMS and NEMS devices working in slip and transition regimes, then we must using DSMC for simulation these devices. DSMC is a physically method and working on the physics bases. Also it was derived from Boltzmann equations by Bird. In this study, we want... 

In recent years carbon nanotubes and other carbon nanostructures such as graphene sheets have attracted a lot of attention due to their unique mechanical, thermal and electrical properties. These structures can be used in desalination of sea water, removal of hazardous substances from water tanks, gases separation, and so on. The nano porous single layer graphene membranes are very efficient for desalinating water due to their very low thickness. In this study, the mechanism of passing water and salt ions through nano porous single-layer graphene membrane are simulated using classical molecular dynamics. In the simulation, in order to separate salt ions from the water, the effects of applied... 

The present thesis is devoted to deeply reconsider the anti-vortex film cooling method and its undiscovered features using numerical optimization and advanced turbulence models. In this regards, a modified turbulent heat-flux model was developed to enhance the predictions in complex flow fields with highly anisotropy and non-equilibrium flow/thermal features. Next, the model was introduced to ANSYS FLUENT 16.0 package to prepare a more accurate flow solver. Then, the solver was coupled with an in-house Differential-Evolution (DE) optimization algorithm to find the optimum configurations of anti-vortex holes for several flow and geometric conditions such as flat-plate, convex/concave surfaces... 

Locating wireless transmitters is one of the most important issues. That’s why many researchers have worked in this subject recently. Communication Engineers always want to optimize the productivity of wireless transmitters. They prefer to cover a region completely by minimum cost, so they use analytical tools for solving this kind of problems. This type of optimization is very useful for cellular Networks. There is a different kind of wireless services such as high-speed Internet services; their goal is maximizing the covered demand points by minimum cost not covering all of them. Experts use maximal covering location problem for modeling this kind of problems. At first, an extension of one... 

During the last two decades usage of unstructured grids was very common in the oil reservoir simulators; which is due to free formulation’s structure and independence of the grids to any special boundary lines or surfaces. The use of these types of grids in Computational Fluid Dynamics texts is widely seen in form of Control Volume discretization techniques; and on the other side, Weighted Integral methods known as Galerkin Finite Elements are one of popular methods to approximate displacement differentials quantities. In this study we tried to review application of a new numerical calculation method – which is a combination of Finite Elements and Control Volume methods – in simulation of...