Sharif Digital Repository

Reduced-order modeling (ROM) is a novel approach in all realms of computational science including reservoir simulation. Among various ROM methods, Trajectory Piecewise Linearization (TPWL) is on its evolution for reservoir applications. Previous investigations reflect promising future for incorporating TPWL into the next generations of enhanced reservoir simulators. In this work, we employ TPWL to investigate the claimed efficiency, robustness and accuracy of this method as a surrogate simulator for a developed reservoir simulator. The self construction of the used simulator gives us the opportunity to explore this method and to examine previous assertions on the subject. The efficiency of... 

This thesis is about modeling of liquid-vapor two phase flows through nozzle. Liquid-vapor two phase flow is very applicable in industries such as boilers, expansion valves, refrigeration and sudden failures in pipelines. Two models are used for modeling of fluid flow through nozzle, transient and steady state. In Both model the solution field is considered as saturated liquid and vapor and the mass, momentum and energy equations as well as equation of state is used for describing of fluid flow properties. Homogeneous equilibrium model is used and for complete modeling of fluid flow heat transfer and friction force is also considered.
Numerical solutions are used for solving of the... 

To have a deeper understanding of Hydraulic fracturing operation, in this study four important parts in this field was developed and simulated. In the first part, continuity and momentum equations for a single phase flow in a propagating penny-shaped fracture inside an impermeable matrix was revisited based on a fixed coordinate system. Its correctness was validated against experimental data and its features were compared with the well-known lubrication theory in analytical form. The new derived continuity equation caused the fracture tip to have a positive and finite pressure while, the conventional model predicted negative infinity for that. In the second part, Finite Volume method was... 

The concurrent flow of oil and water is a common occurrence in the field of multiphase flow in different fields including petroleum industry. In oil and gas, production engineers often face a situation in which more than one phase is flowing through the producers. In such conditions an accurate assessment of pressure loss inside the well plays a vital role in efficient and effective production planning. Changes in well orientation, wellbore diameter, reservoir and fluid properties as well as fluid flow rates are among parameters in which will affect the flow patterns that can occur inside a well during its life time. These flow patterns are created as a result of a competition between... 

Flows in porous media exist in many practical and research fields including water flow in soil, transport of pollution in soil, oil recovery engineering, and etc. Studying the multi-phase flows seems being too complex due to the interactions between fluids or between fluid and media in the porous media, wetting tendency of fluids, intrinsic permeability of the porous media, tortuosity of the flow’s path and etc. Hence, the field and laboratory studies of multi-phase flows is difficult, if not impossible. While numerical methods can handle many of these complexities, many of them are unable to simulate the micro-scale flows. On contrary, Lattice Boltzmann has no such shortcomings and even is... 

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... 

Due to the wide application of plate-fin heat exchangers in various industries such as the petrochemical industry, aerospace industry, air conditioning systems, separation and liquefaction of gases, especially natural gas, boiling, condensation, and transportation industries, proper design of these heat exchangers is necessary. Most of the previous researches in the field of heat exchanger modeling has been done in single-phase mode. The two-phase modeling has been performed, often thermodynamically, and the effects of turbulence and surface tension have been ignored. Thus, in the present study, numerical modeling of the two-phase plate-fin heat exchanger is presented. In this project,... 

In this thesis, the separation process for used and relatively new catalysts of residue fluid catalytic cracking unit by applying an electric field was evaluated. The main purpose of this dissertation is to simulate and design a separation system for separating used and relatively new catalysts of the FCC process in the electrostatic fields. In this regard, various separators were studied, and most of them were simulated under different circumstances. Finally, after examining and analyzing the particle behavior in each of the scenarios, the proposed system was introduced as more effective and efficient than the other separators in order to achieve the ideal separation of the used and... 

The use of stepped weirs dates back at least 3500 years. In this research, the hydrodynamics of gabion stepped weirs have been investigated as a three-dimensional simulation of two-phase flow air-water using Flow3D software and the method of computational fluid dynamics (CFD) analysis. In order to solve the Reynolds-Averaged Navier-Stokes (RANS) equations, the RNG turbulence model (k-ε) was used and the free surface elevation of fluid was determined by the volume of fluid (VOF) method. The experimental results of Wutrish and Chanson (2014) over gabion stepped weirs are used to validate the numerical model simulations. Gabion stepped weirs with steps of 3, 7.5, and 10 cm in height, as well as... 

In nuclear power plants, the fission reaction takes place inside the fuel rods, and the heat generated inside the fuel rods is transferred through the clad wall to the cooling fluid, which is single-phase, subcooled and in the turbulence zone. In the hot channel of the reactor core, where the axial and radial heat flux reaches its maximum state, the fluid leaves the single-phase state and some steam is formed in the area close to the clad wall.Therefore, in some cases, in the hot channel, the steam near the clad wall may reach a point that reduces the heat transfer coefficient, rapidly increases the wall temperature and thus destroys or melts the sheath surface. If this happens, it means... 

Industrial centrifuge fans operate in various industries, specifically heavy industries such as pelletizing plants, steel mills, and cement plants. These fans transfer process gas in the production cycle. In some cases, due to their off-design working conditions, asymmetrical wear and failure happen on one side of the impeller's blades more than the other side. The most important reason is the heterogeneity of the entrance fluid's properties. One of the many critical parameters in this issue is the asymmetric distribution of particles between the two entrances of the fan. This research investigates the asymmetric erosion problem of a specific centrifugal fan with a double-suction side... 

The use of superhydrophobic surfaces is one the most promising methods for reducing the friction and increasing the flow rate in fluid transfer systems. Since in such systems the surface structure plays a key role, in the first part of this study, the performance of the hierarchical nanostructures is explored. These nanostructures are inspired by the superhydrophobic surface of the lotus leaf. The flow is considered between two walls with hierarchical nanostructures and simulate the system via the molecular dynamics (MD) method. The size of the nanostructures and the distance between them have been studied to find whether a design with maximum flow rate exists. The nanostructures have two...