Sharif Digital Repository

In this research, numerical simulation of the impact of a drop on a flat surface with oblique velocity has been performed, using two-phase model of Lattice Boltzmann Method (conservative phase-field). During impact, it is important to investigate two-dimensional drop dynamics and to evaluate the effectiveness of the numerical method used. The model used here restores conservative phase field and preserves mass both locally and globally. In addition, to calculate the slope of the phase field, it calls the center points without engaging finite difference calculations. This makes it efficient for running parallel computations. A fixed dry and hard surface is considered and the drop impacts it... 

Upscaling is an important step in hydrocarbon reservoir modeling which reduces the number of grid blocks of high detailed geological models to prepare them for flow simulation. This helps to speed up computational process, to keep the simulation (CPU) time within a reasonable range and to make future engineering analysis (history matching, comparison of production scenarios, Monte Carlo simulation and etc.) possible. The accuracy of post processing analysis heavily depends on the robustness and validation of the applied upscaling method. Although numerous methods have been proposed in the literature, overemphasizing the effect of scale on the behavior of complex governing equations has... 

Bimetallic nanoparticles with unique structure, synergistic effect between two metals, and the tunable physical/chemical properties have been used for catalysis. Various methods exist for the staibility, and improvement of the catalytic performance of nanoparticles. In this thesis, different co-catalysts were applied to increase tha staibility, and activity of nanoparticles and metal oxides. In this way, Ni-based bimetallic nanoparticles including CuNi, CoNi, and AgNi, and AgPt with different concentrations were synthesized on the cerium oxide nanorods derived from cerium metal-organic frameworks and magnetic graphene oxide nanosheets, respectively and characterized. The catalytic... 

Multi-Scale finite volume (MSFV) method have been developed and applied for multiphase flow in porous media. The most important advantage of MSFV method is its computational efficiency. In this thesis we apply and implement this method to porous media simulation. Then, computational parameters such as coarsening ratio, effect of threshold on adaptive computation and different boundary conditions for computing basis functions are investigated. The two difficulties of sMSFV method are problems with high permeability contrast and problems with high course grid aspect ratio which are considered. In standard MSFV (sMSFV) method reduced boundary condition is used to determine the basis and... 

Smoothed Particle Hydrodynamics (SPH) is a numerical Lagrangian meshless method which has numerous applications in astrophysics, hydrodynamics, free-surface flows, jets and sprays formation. Atomization of continuum liquid to fine droplets or in other words, liquid breakup processes are emerged in many engineering applications such as fuel sprays inside the combustion chamber of internal combustion engines that sizes of produced sprays significantly influence the engine’s efficiency. This research is accomplished to investigate the one-phase and two-phase flows of liquid jet breakup. For this aim, an open source code called SPHysics which solves the flow field by SPH method is utilized. This... 

In this study various ionic liquids (ILs) and their mixtures were coated on Pt/Al2O3 catalyst and the resulted IL-coated catalyst were used in synchronous hydrogenation of cyclohexene and acetone. The rate constants (k) and seletivities (S) toward C=O hydrogenation were determined for several catalysts in various solvents. The solvatochromic parameters (ETN, normalized polarity parameter; π*, dipolarity/polarizability; β, hydrogen- bond acceptor basicity; α, hydrogen-bond donor acidity) were determined for used ILs and solvents and all obtained selectivities were modeled based on solvatochromic parameters of IL layer and bulk solvent using Multiparameter Linear Regression (MLR) method for... 

Reservoir simulation is a useful tool for efficient reservoir management and protective exploitation of non-renewable hydrocarbon resources as the main supplier of development programs in the country. Due to the nature of underground hydrocarbon reservoirs, the simulation faces several challenges, both in rock and fluid parts. These challenges should be overcome in order to provide reliable results from simulations. One of the major challenges pertaining to rock, is large discontinuous variations accompanied by anisotropy of rock permeability fields which causes numerous problems when governing equations are solved numerically. A viable numerical procedure shall account for complex reservoir... 

Formation and detachment of drops are of fundamental importance in studying two-phase flows, such as ink jet printing, emulsion, and spray. Drops are formed under the effects of surface tension forces. After formation, forces like gravity detach the drop from the rest of the fluid. The flow rate is varied from dripping to jetting regime. In this project, formation and detachment of drops were simulated, using LBM with phase field model, which can simulate flows with high-density ratios and is a robust method for applying wetting condition on the walls. Results were validated using single-phase and two-phase flows. After code validation, the oscillations caused by formation and detachment of... 

In this study, the numerical simulation of cavitating flows with compressibility effects is performed. The algorithm employs the multiphase Euler equations with homogeneous equilibrium model. The baseline differential equations system is similar to the one-phase system of equations and comprised of the mixture density, mixture momentums and mixture energy equations. Thephases considered for cavitating flows is liquid-vapor and liquid-gas fields. The system of governing equations is discretized using a cell-centered finite volume AUSM’s upwind scheme. The computations are presented for steady noncavitating/cavitating flows around 1D/2Dproblems for different conditions. A sensitivity study is... 

In this thesis, a fully coupled numerical model is developed for the modeling of the cohesive crack propagation and hydraulic fracturing in porous media using the extended finite element method in conjunction with the cohesive crack model. The governing equations, which account for the coupling between various physical phenomena, are derived within the framework of the generalized Biot theory. The solid phase displacement, the wetting phase pressure and the capillary pressure are taken as the primary variables of the three-phase formulation. The other variables are incorporated into the model via the experimentally determined functions that specify the relationship between the hydraulic... 

Transportation of cuttings and efficiency of the hole cleaning has been one of the major concerns of stake holders in the oil and gas industry.This is because a successful drilling program is a key to a productive and profitable oil and gas business. A successful drilling program is as a result of an efficiently cleaned hole. On the other hand, a poor or inefficient hole cleaning implies accumulation of cuttings or formation of cuttings bed in the well. This often leads to decreased rate of penetration, increased cost of drilling, fractured formation, increased plastic viscosity of mud as a result of grinding of cuttings and stuck pipe. Hole cleaning is effected primarily with a drilling... 

Drop formation is an interesting field of research due to its wide-range of applications, such as drug delivery, biomedical studies, pharmaceutical industry, Lab-On-Chip (LOC) devices, etc. In recent years, researchers have used numerical studies to better understand how the process of forming and carefully examining the factors that affect quality improvement. One of the most effective methods in controlling the size and the process of drop formation is use of external force in microfluidic devices. Among the external force in this study, an electric field with oscillating current was used. Rapid methods for creating, deforming, and breaking up of drops in microfluidic applications are... 

Surface Jet Pump (ejector) is one of the most widely used equipment in the industry, which can be used in the oil and gas industry, propulsion and refrigeration systems. One of the uses of surface jet pumps in the oil and gas industry is the use of high-pressure wells to transfar low-pressure wells. The purpose of this research is to measure the transmission feasibility of low-pressure wells using surface jet pumps and optimize surface jet pump geometry. The purpose of optimizing the geometry of the surface jet pump is to maximize the ratio of the discharge rate from the low-pressure well to the high-pressure flow (entranment ratio). One of the most common methods for optimizing the... 

Resin Transfer Molding (RTM) which is one of the categories of Liquid Composite Molding (LCM) process, is considered as one of the most important process in polymer composite manufacturing. To improve this manufacturing method and reaching higher qualities, numerous modified methods has been developed. One of these modified methods is Vaccum Assisted Resin Trasnfer Molding with Flexible Tooling which is considerably applicable in manufacturing parts with high quality, large and complex geometry. Although, this manufacturing method has variety of advantages, there are some problems such as void formation making production difficult and dependent to experimental trial and error. So numerical... 

Most of the time there are three different materials in oil wells; Oil, water and gas. Measuring volume percentage and flow of the individual materials (phases) is an important issue, due to their critical role in extraction process control. Measuring tool should be able to measure flow and percentage of each phase in a case that they are separated (in deviated wells due to gravity). In addition, the measurement should be carried on in a high temperature and high pressure environment and in presence of corrosive substances. Most of previous researches on Multi-Phase Flow Meter (or MPFM) led to mechanical methods to measure flow and they usually use electrical impedance or permittivity for... 

Flow measurement in both types of single phase and multiphase has a crucial place in a wide variety of industries, specially petroleum industry. for single phase flowmeters, improving their precision using different types of mechanical, mathematical and analytical techniques will be considered as an important step. Using multiphase flow meters will cause no need of volume catching and costly separators and also make us capable of taking well-timed decisions in production management. for making flow meters weather multiphase or single phase, there is a crucial need of a multiphase flow loop. To achieve that, an 8-meter-long flow loop using transparent Plexiglas pipes with inside diameter of... 

In this thesis an SPH method is used for simulating multiphase two- and three-dimensional Newtonian fluid flows. The weakly compressible algorithm consists of two steps of prediction and correction. In the prediction step, the velocity field is integrated forward in time without enforcing incompressibility. The correction step consists of enforcing incompressibility by solving the pressure Poisson equation which creates a trade-off between the pressure and density variations. The surface tension force is applied in the linear momentum conservation equation by the divergence of the surface stress tensor. Advanced techniques are applied to achieve better convergence and reduce pressure-related... 

In a single chemical plant, the operation of each unit operation is not independent of each other. In the other hand, the main operations are performed in reactors following by several separation steps including distillation and purification units. The total energy requirements are sullied by the heat exchanger networks. The performance of these systems is improved by integration and intensification of the reactor and distillation column in a single unit. The main objective of the present work is to provide an effective design approach to intensify the reactor and distillation column. In a reactive distillation column, the reaction and separation is done in a single unit. Increasing... 

This study is aimed at simulation of double emulsion formation in a microfluidic double flow focusing device which consists of two cross-junctions connected serially. The water in oil (w/o) emulsions are produced in the first junction. In the second junction, water in oil emulsions are encapsulated by an outer aqueous phase to generate water in oil in water (w/o/w) double emulsions. Water in oil emulsions are formed in hydrophobic channels and water in oil in water double emulsions are formed in hydrophilic channels. A three phase numerical model, based on the VOF-CSF method, is developed for simulating the process of double emulsion formation. An adaptive mesh refinement technique is... 

Smoothed Particle Hydrodynamics (SPH) is a Lagrangian method for simulation of fluid flow. Movable particles are used to interpolate fluid properties instead of fixed Eulerian grids in this method. By essence, the aforesaid particles are movable points which carry the fluid properties such as temperature, enthalpy, density, etc. these variables can also be the stress, strain or the rheological properties of the fluid. Thus, this method needs no grids and the fluid properties are calculated using an interpolation mechanism which classifies this method as meshless. A computational code is designed using SPH for the simulation of multiphase flows. Usage of the Lagrangian formulation has made it...