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hydraulics
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Total 337 records
Impact of Net Stress on Stress State of an Unsaturated Sand
, M.Sc. Thesis Sharif University of Technology ; Khosravi, Ali (Supervisor)
Abstract
Results of an advanced suction controlled triaxial test device in an attempt to define the constitutive relationship between suction stress and matric suction (Suction Stress Characteristic Curve, SSCC) for unsaturated sand was presented. The suction stress is a macroscopic stress that incorporates the effects of capillary van der Waals forces cementation, and electrical double-layer repulsion into the definition of effective stress for unsaturated soils. Results of previous studies on silt and clay indicated that variations in the suction stress, during drying path had a non-linear increasing trend with matric suction with greater values upon wetting. However, due to different material...
Investigating the Propagation of Thermal-hydraulic Noise in PWRs in Two phases
, M.Sc. Thesis Sharif University of Technology ; Vosoughi, Naser (Supervisor)
Abstract
The core behaviour of a nuclear reactor might be fluctuated (deviations from the normal operating conditions) in operating conditions due to various reasons. Control rod vibrations and the alterations of coolant temperature and velocity could be the main reasons for the fluctuations. These fluctuations lead to neutronic flux noise and subsequently power noise. The main objective of the current thesis was to study the thermal-hydraulic noise of the PWRs in two-phase with the emphasis on VVER-1000, which is similar to the Bushehr-1 nuclear reactor. By considering the possibility of existing two-phase flow (maximum allowable quality is about 14%) in hot channel of the PWRs, thermal-hydraulic...
The Passive Design and Development of Digital Microfluidic Dynamic Memor
, M.Sc. Thesis Sharif University of Technology ; Moosavi, Ali (Supervisor)
Abstract
Microfluidics with the ability to control Nano-to-Pico meter volumes have caused the revolution in the systems of analytical biology and chemistry. However, the most Lab-On-Chip technologies (LOCs) depend on external control elements, so a lab is required to operate a chip. Bubble or drop logic through the bubble (drop) can control the flow internally and intrinsically digitally without utilizing of off-chip or moving components. Non-linearity is applied by using mutual drop-drop' effects on reversible linear flow in low Reynolds. for the proper exploitation of microfluidic systems, It is necessary to control droplet generation systems in one chip appropriately. The most crucial part of the...
Design for Fabrication of a Knee Prosthesis Wear Simulator
, M.Sc. Thesis Sharif University of Technology ; Durali, Mohammad (Supervisor)
Abstract
Total knee replacement surgery is the most common joint replacement in the world. Considering the increasing rate of this procedure and costs and difficulties of the repeated operation, many efforts have been made to improve the performance and lifetime of implants. The Polyethylene component of the implant is the most prone component to fail due to wear. To evaluate new knee prosthesis designs, it is necessary to have a wear test simulator. Objective of this project is to detail design a knee prosthesis wear simulator according to ISO 14243 in order to investigate the performance of prosthesises in long term and under in-vivo conditions. During this project, studies have been made to get...
Impact of Stress on Permeability of Packed Hydraulic Fracture
, M.Sc. Thesis Sharif University of Technology ; Shad, Saeed (Supervisor) ; Fatemi, Mobeen ($item.subfieldsMap.e)
Abstract
Given the broad role of oil and gas playing in the world economy, finding the hydrocarbon reservoir that economically is affordable is quite significant. Some of the unconventional oil and gas reservoirs are important from the economic point of view since they produce insufficient hydrocarbon due to either low permeability or damage during drilling and production. Hydraulic fracturing is one of the most significant methods for improving the productivity of wells and reservoirs. Hydraulic fracturing acts by affecting on reservoir rock physic. In the current century, this approach has an essential effect in enhancing the permeability and production of reservoirs by creating, extending and...
Modeling and Design Analysis of an Aircraft Longitudinal Reversible Flight Control System and its Enhancement to Irreversible One
, M.Sc. Thesis Sharif University of Technology ; Pourtakdoust, Hossien (Supervisor) ; Raeesi Charmkani, Kamran (Supervisor)
Abstract
Flight control system (FCS) design, analysis and modeling has an important role in aircraft design and development process. However, FCS analysis and studies are rarely focused at university levels and its know-how and technical issues are almost proprietary to various aircraft industries. One of the key goals of this thesis is to express, introduce and implement the processes that need to be followed for a sample longitudinal reversible FCS design (RFCS), where the modelling aspects are described for an existing aircraft. The latter is achieved using existing drawings, system and aerodynamic data of an existing aircraft utilizing commercial tools such as CATIA for initial design and ADAMS...
Numerical Simulation of Hydraulic Fracturing in Porous Media Considering Two Phase Flow and Thermal Effects Using Mesh-less XEFG Method
, Ph.D. Dissertation Sharif University of Technology ; Pak, Ali (Supervisor)
Abstract
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...
Numerical Modeling of Fluid Flow and Proppant Transport in Hydraulic Fracture Using Extended Finite Element Method
, Ph.D. Dissertation Sharif University of Technology ; Khoei, Amir Reza (Supervisor) ; Shad, Saeed (Co-Supervisor)
Abstract
Transport phenomena in porous media play important role in many areas of subsurface hydrology, geo-physics, environment, energy and petroleum. The work in the field of numerical modeling of fractured porous media is yet an open area of research. The classic finite element method (FEM) has some limitations in modeling of discontinuities like fracture. FEM mesh should conform with the geometry of the fracture. Presence of fracture imposes discontinuity in pressure field of fluid phases and displacement field of solid phase (rock). To represent the fractures, the extended finite element method (X-FEM) can be used in which the standard finite element approximation of the field variables is...
Modeling and Laboratory Evaluation of Rheological Properties of Water based Mud for Horizontal Extended Reach Well
, M.Sc. Thesis Sharif University of Technology ; Taghikhani, Vahid (Supervisor) ; Ghazanfari, Mohammad Hossein (Supervisor) ; Tahmasbi Nowtarki, Koroush (Co-Supervisor) ; Kalhor, Mojtaba (Co-Supervisor)
Abstract
One of the most important challenges in drilling horizontal and directional wells is the optimization of hydraulics and hole cleaning and ECD management. In these wells, poor hole cleaning can lead to formation of cutting bed on the low side of the annulus and cause problems such as stuck pipe or increase in torque and drag. Also poor hydraulic design can lead to decrease in rate of penetration and thus, increase in costs. Mud weight should be placed inside the range of mud window (more than pore pressure and less than formation fracture pressure) in order to prevent kick of reservoir fluid or mud loss.In this thesis, the main goal is to optimize hydraulics and hole cleaning and manage ECD...
Study of the Effects of Geo-mechanical and Hydro-mechanical Parameters on Hydraulic Fracturing Characteristics in Oil Reservoirs by Numerical Modeling
, M.Sc. Thesis Sharif University of Technology ; Pak, Ali (Supervisor)
Abstract
Increasing the permeability of hydrocarbon reservoirs by creating artificial cracks that are induced by injection of fluids under high pressures is called Hydraulic Fracturing operation. This method is widely used in petroleum reservoir engineering. For design of Hydraulic Fracture operations, a number of methods have been developed. KGD and PKN are the first and most used methods in this area and despite the development of advanced softwares in recent years, these methods are still popular and are used in a number of softwares. KGD is commonly used for induced fractures where the height of fracture is greater than its length, and PKN is normally used where the length of the fracture is...
Effect of DEM Resolution on Hydraulic Modeling of Flood Inundation Area: Case Study of Gorganrood River, Northeast of Iran
, M.Sc. Thesis Sharif University of Technology ; Ataie Ashtiani, Behzad (Supervisor)
Abstract
Digital Elevation Models (DEM) is a crucial element of hydraulic models, including floods. Due to the lack of high-precision topographic data, including ground-based mapping hydraulic modeling is challenging. In recent years, remote sensing data, extensively used by many researchers in hydraulic modeling due to global coverage and free access. One of the most critical questions in hydraulic modeling is the efficiency of these DEMs in flood simulation. This research focused on using remote-sensing-based DEMs, such as SRTM-30m and 90m, ASTER-30m, and ALOS-12.5m DEMs, on the performance of the HEC-RAS-2D model in the Gorganrood river.The results showed that ALOS and SRTM-30m DEMs' accuracy and...
Laboratory Investigation of the Effects of Sodium Chloride Concentration on Soil Water Retention Curve and Volumetric behavior Using an Unsaturated Automatic Oedometer
, M.Sc. Thesis Sharif University of Technology ; Sadeghi, Hamed (Supervisor)
Abstract
Laboratory studies to investigate the effects of different saline concentrations (such as sodium chloride or calcium chloride) on the soil water retention behavior of clayey soils and their volumetric changes have received much attention recently. However, many previous studies have investigated these effects in only one path of the SWRC (wetting or drying path) and the effects of saline concentration on hydraulic hysteresis have not been considered. In addition, researchers have frequently studied these effects on SWRC on clay samples, and little research has been done on collapsible soils. Therefore, the most important purpose of this study is to investigate the effects of increasing...
Development of a New Analytical Model based on Soil-water Retention Curve Microstructure Considering the Effects of Osmotic Potential
, M.Sc. Thesis Sharif University of Technology ; Sadeghi, Hamed (Supervisor)
Abstract
The soil-water retention curves (SWRC) is an unsaturated soil mechanics hydro chemical state surface, which expresses the relationship between the soil suction and water content. The soil-water retention curve could describe the water adsorption and desorption process that happened in soils. The difference between the desorption or drying retention curve and the adsorption or wetting retention curves in a specific soil specimen indicates the hydraulic hysteresis phenomenon. Generally, the amount of water remaining in the drying process is greater than the amount of water adsorbed in the wetting process at a certain amount of suction. Suction due to the combined effects of capillary and...
Performance Analysis and Design of Spectral Noise Logging Tool
, M.Sc. Thesis Sharif University of Technology ; Movahedian, Hamid (Supervisor)
Abstract
Today, one of the most important concerns of oil and gas wells is to increase the efficiency of wells. To increase efficiency, well integrity must be monitored. One of the factors that destroy the integrity of the well is the creation of hydraulic fractures inside the oil and gas wells, which is one of the main factors that reduce the efficiency of the well. Hydraulic fractures cause water, gas and other materials to leak into the well or oil and gas to leak out of the fracture, which in both cases reduces the efficiency of the well. One of the most important technologies for identifying hydraulic fractures is the use of SNL tools from oil and gas wells. The oil and gas well SNL tool listens...
Development of a High-precision Unsaturated Permeameter for Characterizing Two-phase Flow Through Deformable Porous Media
, M.Sc. Thesis Sharif University of Technology ; Sadeghi, Hamed (Supervisor)
Abstract
Given that highly deformable natural deposits such as collapsible and swelling soils make up more than one-fifth of the land surface and are generally in unsaturated conditions, behavioral measurement of this type of soil including accurate measurement of its hydraulic properties is important. The challenges of designing and implementing construction infrastructure, along with the most reported financial losses due to the presence of these soils, double the importance of studying the behavior of these soils. The large volume changes of these soils in contact with water (equivalent to a volumetric strain of more than 5%) has been a major challenge for researchers in predicting the...
Effects of Microstructure and Salinity Concentration on Hydraulic Conductivity of Silty Clay Soils
, M.Sc. Thesis Sharif University of Technology ; Sadeghi, Hamed (Supervisor)
Abstract
Various contaminants and their leachate, when they penetrate into the soil, cause changes in soil microstructure, this change in microstructure leads to changes in soil permeability and volume. In this study, first, the effects of soil microstructure change on the hydraulic conductivity of saturated soil were investigated using the change in initial saturation degree during compaction for compacted samples and the change in sample construction in reconstituted samples. Also, the simultaneous effect of changing the initial microstructure and salt solution on the hydraulic conductivity of saturated silty clay soils using a three-axial permeability device with the ability to measure volume...
The Study of the Effect of Geomechanical Parameters on Hydraulic Fracturing Characteristics in Hydrocarbon Reservoirs by Numerical Modeling
, M.Sc. Thesis Sharif University of Technology ; Pak, Ali (Supervisor)
Abstract
The exploitation of oil and gas were changed dramatically with the advent of hydraulic fracturing. By using enhanced oil recovery methods in unconventional reservoirs, USA could raise the rate of production in comparison with the rate of consumption. Hydraulic fracturing is one of the enhanced oil recovery methods.The purpose of this research is the study of the effects of geomechanical parameters in the characteristics of the cracks induced by hydraulic fracturing in unconventional oil reservoirs. The minimum in-situ stress and tensile stress of rock can be overcome by injecting fluid and thus the rock will be cracked. Changes in geomechanical parameters such as modulus of elasticity,...
Numerical Modeling of Solid Transport in a Transparent Fracture
, M.Sc. Thesis Sharif University of Technology ; Shad, Saeed (Supervisor) ; Zivar, Davood (Co-Supervisor)
Abstract
Hydraulic fracturing, as an industry-leading technology, has proven to be very efficient in increasing the productivity of oil and gas wells. Therefore, this technology has been taken into attention in recent years and the number of hydraulic fracturing operations has been increasing. In order to enhance the efficiency of this technology, the final transmissibility of the fracture needs to be at the maximum possible value. To do so, proppant injection is the most common way to maintain a fracture open. To achieve a successful hydraulic fracture operation, detailed knowledge of the particle's transport and distribution inside the fracture is needed.In this study, a static fracture geometry...
Probabilistic Assessment of Flood Risk Using Data-Driven Flood Depth Modeling: A Case Study of Poldokhtar City
, M.Sc. Thesis Sharif University of Technology ; Safaie Nematollahi, Ammar (Supervisor)
Abstract
The present study aims to evaluate the flood risk of Poldokhtar city probabilistically using Monte Carlo Simulations (MCS). Two-dimensional (2D) models, which are highly accurate, have been used widely for flood modeling. However, they are not suitable for applications such as MCSs that need to be repeated many times or real-time flood forecasting applications, which require that flood inundation maps quickly be produced. In the current study, we developed a data-driven surrogate model based on the Least Squares Support Vector Machine (LS-SVM), a supervised machine learning method, to predict flood depth in order to simulate similar results to 2D hydraulic modeling. HEC-RAS was used for 2D...
Impacts of Water Level Rise and Fall of a Hypersaline Lake on Seawater Intrusion: Case of Lake Urmia, Iran
, M.Sc. Thesis Sharif University of Technology ; Ataie Ashtiani, Behzad (Supervisor)
Abstract
Lake Urmia located in the NW of Iran, has lost 96 percent of its volume in 20 years and become a national crisis. During this shrinkage, the lake level has fallen by 8 m, and its concentration has increased up to 380 g/l. Regarding the vast area Lake Urmia basin is covered, the hydrological characteristics of the basin varies a lot, which affects the aquifers response to the seawater intrusion. In order to study the seawater intrusion in the lake’s aquifer, 18 cases with different hydraulic gradients, hydraulic conductivities and bathymetries were defined. All of these cases were run under three different scenarios in sequence. First, steady state scenario is preformed, then the lake level...