Sharif Digital Repository

In this study, a fully coupled three-dimensional numerical analysis of two-phase fluid flow and heat transfer through deformable porous media is presented in the context of extended element free Galerkin method. By coupling momentum balance equation for the whole mixture, continuity equations of wetting and non-wetting fluid phases and energy balance equation, the developed numerical algorithm is capable of simulating a wide range of engineering problems such as CO2 sequestration, nuclear waste disposal in deep underground strata, hydraulic fracturing in oil and gas reservoirs and so on.By taking the advantages of partition of unity property of MLS shape functions, weak and strong... 

Recently, there has been a strong interest in the development of a new class of meshfree methods. As an alternative to the finite element method (FEM), mainly due to elimination of high cost mesh generation processes. In addition, the size effect is currently a subject of increasing interest since it is an important parameter in predicting, correctly, the mechanical behavior of materials with microstructure. It was well established that classical linear elastic continua which neglects the higher order terms is not able to describe size effects. In contrast, enhanced continuum theories such as nonlocal or gradient-dependent models do involve an internal length scale. Thorough this length... 

In this dissertation, hybrid meshless method for electromagnetic wave scattering has been presented. The idea of the dissertation is the use of two robust meshless shape functions i.e. MLS and RPIM simultaneously to solve differential and integral equations from 3D scattering equations respectively. Finite element method (FEM) and method of moments (MoM) are used extremely for computing scattering problems. These methods are powerful and their results are accurate enough. One of their disadvantages is the need of mesh generation. Mesh generation in FEM is a time consuming process. Furthermore, in electromagnetic problems that involve geometrical, the use of an underlying mesh creates... 

Hydraulic fracturing is a process during which a viscous fluid under relatively high pressure and flow rate is injected into a wellbore to induce and propagate a system of cracks in the ground.Hydraulic fracturing of underground formations has been widely used in different fields of
engineering, such as petroleum engineering, geotechnical engineering, environmental engineering, mining engineering,and so on.Despite the technological advances in the techniques of in-situ hydraulic fracturing, the industry lacks a realistic and reliable numerical model to design cost - effective and efficient hydraulic fracturing treatment.This is due to the complex interaction and strong coupling between... 

During the past decade, element free methods have achieved great successes. One of these methods is the so called RKPM which has a suitable structure for use in fracture mechanics problems. Despite all characteristic abilities of element free methods; these methods due to their higher order continuous differentiable approximations fail to model discontinuous material properties of the subjected domains. In this study by improving the collocation method in RKPM treatment of such conditions have been achieved. Also in this study performance of a new meshfree method in fracture mechanics problems has been analyzed. GRKPM is one of these methods which its suitable accuracy and convergence has... 

Greenhouse gas emissions into the atmosphere have multiplied with the increase in fossil fuel consumption, which directly affects global warming. Global warming has other undesirable consequences such as rising sea water level and declining snow cover. To reduce greenhouse gases in the atmosphere, researchers have studied various ways, one of which is carbon dioxide injection into underground formations, which has a significant effect on reducing the amount of these gases in the atmosphere. Existence of high volume underground reservoirs with suitable conditions for gas injection to prevent gas escape has made it a widely used and effective method. Despite many advantages of this method, it... 

Land subsidence is one of the consequences of groundwater withdrawal. This phenomenon can cause cracks in the surrounding structures, balance out the foundation of bridge piers, damage to roads, pipelines, etc. The main goal of this study is to provide a coupled flow-deformation model capable of simulation of land subsidence associated with groundwater extraction in unsaturated isotropic and true anisotropic aquifer systems, using the element-free Galerkin (EFG) method. Using this model and based on the geological features of an aquifer, we can easily forecast the hydraulic head change and land subsidence in different places and times during groundwater pumping. According to the current... 

Due to a rapid growth in the consumption of fossil fuels, the emission of greenhouse gases has multiplied in the atmosphere in the past few decades. This issue can directly affect on the rise of global temperature. Because of the intensification of the global warming, international organizations are looking for ways to reduce the greenhouse effect. One of these methods is injecting and trapping greenhouse gases, especially carbon dioxide, resulting from the operation of power plants and other large industries and preventing it from entering the atmosphere. The injection of carbon dioxide in underground salt water reservoirs can have various effects such as mechanical, hydraulic, thermal, and...