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Total 102 records
Red Tide Development Modelling by MIKE Software (in Persian Gulf)
, M.Sc. Thesis Sharif University of Technology ; Abasspour, Majid (Supervisor)
Abstract
Land sourced marine pollution, overexploitation of living marine resources, destruction of habitat and introduction of harmful aquatic organisms and pathogens to new environment had been identified as the four greatest threats to the world’s oceans. Since invasive species can not be cleaned or absorbed in the ocean so, their effects on the environment are irreversible. Red tide is one of the invasive spieces and is a colloquial term used to refer to one of a variety of natural phenomena known as algal bloom. This phenomenon occur in estuarine, marine, or fresh water and algae accumulate rapidly in the water column and resulting in coloration of the surface water, varying in colour normally...
Simulation of Advection and Diffusion of Hazardous Noxious Substances (HNS) in Sea, Case Study: Oil Derivations in Caspian Sea
, M.Sc. Thesis Sharif University of Technology ; Raie, Mohammad (Supervisor)
Abstract
Hazardous Noxious Substances (HNS) are chemicals. Due to population increase and as a result, increased demand, HNS transportation by sea has been raised. Gasoline and diesel are two kinds of HNS which have the largest transported amount via northern ports of Iran especially Anzali port. So, HNS spill from tankers is an imminent event and threat for environment of Caspian Sea. Organizations that are concern about the health of coasts and seas water always try to use the softwares to simulate the currents and waves to define the hydrocarbon slick transport. Therfore in this study, a 2D hydrodynamic/oil spill model has been developed to predict the transportation of diesel and gasoline slick...
The Effect of Sea Current on an Artificial Island
, M.Sc. Thesis Sharif University of Technology ; Abbaspour Tehrani Fard, Majid (Supervisor)
Abstract
With regards to rapid growth of world population, coastlines have limited natural resources and capacity for human settlement. To tackle the problem the idea of constructing artificial islands could be a solution. Since the artificial islands are semi-enclosed body of water designed to attract not only tourists but also settlements, the flow current pattern and residence time of water should be studied in detail in order to ensure adequate water quality in the surrounding area. In this study, an artificial island is planned to be constructed around Kish Island in Persia Gulf. In this article the effects of different geometries on circulation and residence time of water are investigated...
Extension of the Macroscopic Traffic Flow Model
, Ph.D. Dissertation Sharif University of Technology ; Nassiri, Habibollah (Supervisor)
Abstract
Traffic flow modeling on different levels was always the topic of many studies. In this regard, many researchers have tried to eliminate traffic problems by developing precise models. Therefore, in this study and in its two major parts, we developed two models: one macroscopic and one microscopic. Like previous studies, the main purpose here was the development of traffic flow models that have better precision and give more information about the mechanism behind the traffic phenomena. Our focus was on the free spaces in front of drivers which were considered in a macroscopic traffic flow model and resulting microscopic traffic flow model.First part, addresses the first-order extension of the...
Introducing of Arc-Shaped Wall-Jet in Boundary Layer Flow Control Application in Film Cooling-Numerical Simulations
, M.Sc. Thesis Sharif University of Technology ; Javadi, Khodayar (Supervisor)
Abstract
In this research special type of jets those calls Arc-Shape Jets are studied. The meaning of this research is an effort to introduce this types of jets as a new method to film-cooling approach. In the primary section, the fitness of this scheme on a flat plate is studied. After this section, according to the results, this method is implemented on a turbine blade surface. According to the results, this method of film-cooling has suitable effectiveness in lateral direction, this has a reason of radially injection of the coolant jet. The main feature of this concept is operating by mass flow rate of much lower than other schemes. So that in a regular injection of a 45 degrees of actuator arc,...
Thermal-Hydraulic Simulation and Analysis of Two-Phase Thermal Shock in Pressurized Light Water Power Plants
, Ph.D. Dissertation Sharif University of Technology ; Ghofrani, Mohammad Bagher (Supervisor)
Abstract
As a result of fission reaction in a nuclear reactor, the produced high neutron flux would affect the material of Reactor Pressure Vessel (RPV). This neutron radiation has a detrimental impact on the mechanical properties of the RPV material such as hardening (or embrittlement) while neutrons are absorbed by the material. A major concern in embrittled RPVs is propagation of critical flaw causing through-wall cracks. Some transients leading to overcooling of RPV intensify the propagation of theses cracks and result in thermal load on RPV, known as Pressurized Thermal Shock (PTS). Such situation could be created in case of Emergency Core Cooling System (ECCS) actuation which leads to injection...
Numerical Modeling of Film Condensation in the Plate-Fin Heat Exchanger Used in the CO2 Capturing and Storage Process
, M.Sc. Thesis Sharif University of Technology ; Saeedi, Mohammad Hassan (Supervisor)
Abstract
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,...
Investigating Engineering Solutions to Preserve Goragan Bay:Dreding Ashouradeh Channel
, M.Sc. Thesis Sharif University of Technology ; Raie, Mohammad (Supervisor)
Abstract
Gorgan Bay, registered as a biosphere reserve, has environmental value in the country and the world. The bay is separated from the Caspian Sea by sedimentation in the sandy spit of Miankaleh. Due to the declining water level of the Caspian Sea and the possibility of hydraulic connection disruption and closure of its openings, this water body may face many problems in the future. Main problems are the increase in water retention time and, consequently, the decrease in water quality and the problem of local access during the seasons when the water level drops. In this study, engineering solutions have been studied in proportional with the current conditions of the Gorgan Gulf, which include...
Investigating Sediment Transport in Deep Reservoirs Using the 3D Numerical Model MIKE3
, M.Sc. Thesis Sharif University of Technology ; Shamsai, Abolfazl (Supervisor) ; Ghaemial, Mohsen (Supervisor)
Abstract
Nowadays, in the world and our country, Iran, sediment transport and the phenomenon of sedimentation are of great importance. The entry of water flow with suspended sediments into the dam reservoir by floods with different return periods during the initial period of dam construction causes a considerable part of the helpful volume of the reservoir to be filled with sediments. As a result, the discharge of these sediments and the methods that exist in this field should be studied so that a large volume of reservoir water is not wasted during the discharge of these sediments. In this research, the opening time and extent of the bottom outlets of Qeshlaq Dam when the flood enters the reservoir...
Gorgan Bay Water Salinity Modeling under the Scenario of Water Transfer from Caspian Sea by Pipeline
, M.Sc. Thesis Sharif University of Technology ; Raie, Mohamad (Supervisor)
Abstract
Gorgan Bay and Miankaleh Wetland have been exposed to various environmental risks in the past years due to the decrease in the Caspian water level and the subsequent decrease in the water level of these water bodies. 2 channels, Chapgoli and Ashuradeh, are the only ways connecting the Gulf with the Caspian Sea. If the water level of the Caspian Sea and the Gulf continue to decrease, these 2 channels will be completely blocked and the connection between the Gulf and the sea will be completely closed. Due to the low depth of the bay and high evaporation on this water body, the blockage of these 2 channels will eventually lead to drying up of the bay or changing the flora and fauna of the area....
Mechanistic Investigation of Enhanced Oil Recovery by Engineered Water Using Computational Fluid Dynamics at Pore Scale
, Ph.D. Dissertation Sharif University of Technology ; Ayatollahi, Shahaboddin (Supervisor) ; Mahani, Hassan (Supervisor)
Abstract
Despite the proven advantage of the engineered water flooding technique, a coherent and mechanistic understanding of the fundamental phenomena occurring at pore scale is lacking. Most of the available simulation models have a phenomenological approach and have limited predictive capability. One of the key questions is how to justify and relate large (Darcy) scale observations to effects and phenomena that essentially occur at much smaller scales (i.e. pore and molecular level). Furthermore, two-phase flow dynamics and the effect of complex interplay between wettability, capillary number, and ions dispersion in a heterogeneous porous medium on the trapping and mobilization of oil at pore...
Modeling of Brine Water Discharge into the Sea from Desalination Plants and Its Impacts on Sea Environment
, M.Sc. Thesis Sharif University of Technology ; Abbaspour Tehrani, Madjid (Supervisor) ; Mehdigholi, Hamid (Supervisor)
Abstract
Recent studies have shown that almost 40% of the world's population faces a water crisis, and this amount will reach about 60% by 2025. Due to limited freshwater resources and the increasing world population, we have to use seawater desalination systems to supply water to this growing population. One of the outputs of desalination plants in addition to freshwater is saline effluent or brine water, which is the most important environmental impact of these plants. In this study, an attempt has been made to investigate the various factors affecting the discharge and release of saline effluent from desalination plants and observe its impact on the ecosystem and marine environment. In this...
Numerical Simulation of Oil Spill in Gheshm Channel
, M.Sc. Thesis Sharif University of Technology ; Raie, Mohammad (Supervisor) ; Ataie Ashtiani, Behzad (Supervisor)
Abstract
To meet the growing energy demand worldwide, oil and gas exploration and production activities have increased rapidly both in onshore and offshore areas. The produced oil from the ocean bed is transported onshore either by ship or pipeline. This has increased the risk of oil spill in the coastal areas. In order to prepare an emergency preparedness plan and to assess the magnitude of risk involved in transporting and offloading oil, oil spill simulation studies play an important role. This research describes a simulation of oil spill in coastal area of Persian Gulf, near Hormoz Strait which is called Gheshm Channel (Khouran Strait), using MIKE 21 model. The Gheshm Channel contains huge...
Traffic State Prediction via Macroscopic Fundamental Diagram in an Urban Network
, M.Sc. Thesis Sharif University of Technology ; Nassiri, Habibollah (Supervisor)
Abstract
The road authorities of a city have the responsibility of constantly assessing how well their city performs when traffic conditions are taken into account. In many metropolises around the world, if not taken preventive measures, there will be observed a density above the network capacity and a noticeable decrease in the level of service, especially in the morning and evening peak hours. Also, the dynamic congestion pricing of certain areas based on the traffic condition has always been considered significant by urban planning officials. Since this is not possible except by constantly assessing the current traffic state, a variety of methods have been used to predict the future traffic...
Investigation of obstacle effect to improve conjugate heat transfer in backward facing step channel using fast simulation of incompressible flow
, Article Heat and Mass Transfer/Waerme- und Stoffuebertragung ; Volume 54, Issue 1 , 2018 , Pages 135-150 ; 09477411 (ISSN) ; Moazezi, A ; Sharif University of Technology
Springer Verlag
2018
Abstract
The current study investigates the conjugate heat transfer characteristics for laminar flow in backward facing step channel. All of the channel walls are insulated except the lower thick wall under a constant temperature. The upper wall includes a insulated obstacle perpendicular to flow direction. The effect of obstacle height and location on the fluid flow and heat transfer are numerically explored for the Reynolds number in the range of 10 ≤ Re ≤ 300. Incompressible Navier-Stokes and thermal energy equations are solved simultaneously in fluid region by the upwind compact finite difference scheme based on flux-difference splitting in conjunction with artificial compressibility method. In...
Experimental and modelling study of gravity drainage in a three-block system
, Article Transport in Porous Media ; Volume 136, Issue 2 , 2021 , Pages 471-494 ; 01693913 (ISSN) ; Karimi Malekabadi, A ; Ghazanfari, M. H ; Rostami, B ; Sharif University of Technology
Springer Science and Business Media B.V
2021
Abstract
Gravity drainage is known as the controlling mechanism of oil recovery in naturally fractured reservoirs. The efficiency of this mechanism is controlled by block-to-block interactions through capillary continuity and/or reinfiltration processes. In this study, at first, several free-fall gravity drainage experiments were conducted on a well-designed three-block apparatus and the role of tilt angle, spacers’ permeability, wettability and effective contact area (representing a different status of the block-to-block interactions between matrix blocks) on the recovery efficiency were investigated. Then, an experimental-based numerical model of free-fall gravity drainage process was developed,...
Theoretical comparative assessment of single- and two-phase models for natural convection heat transfer of Fe3O4/ethylene glycol nanofluid in the presence of electric field
, Article Journal of Thermal Analysis and Calorimetry ; Volume 146, Issue 2 , 2021 , Pages 981-992 ; 13886150 (ISSN) ; Tavakoli, S ; Pishvaie, M. R ; Sharif University of Technology
Springer Science and Business Media B.V
2021
Abstract
Natural convective heat transfer of Fe3O4/ethylene glycol nanofluids around the platinum wire as a heater in the absence and presence of the high electric field was investigated, numerically. The control volume finite element method was employed for the numerical simulation. Effects of the flow model, the volume fraction of nanoparticles, Rayleigh number, and the electric field intensity on the natural heat transfer coefficient (NHTC) of nanofluid were studied. Simulation results of single-phase and two-phase flow models showed that the two-phase model could better predict experimental data than the single-phase model due to take into account the velocity of each phase in the mixture. The...
Modeling fluid flow in fractured porous media with the interfacial conditions between porous medium and fracture
, Article Transport in Porous Media ; Volume 139, Issue 1 , 2021 , Pages 109-129 ; 01693913 (ISSN) ; Khoei, A. R ; Sharif University of Technology
Springer Science and Business Media B.V
2021
Abstract
One of the most popular models that has been applied to predict the fluid velocity inside the fracture with impermeable walls is the cubic law. It highlights that the mean flux along the fracture is proportional to the cubic of fracture aperture. However, for a fractured porous medium, the normal and tangential interface conditions between the fracture and porous matrix can change the velocity profile inside the fracture. In this paper, a correction factor is introduced for flow equation along the fracture by imposing the continuity of normal and tangential components of velocity at the interface between the fracture and porous matrix. As a result, the mean velocity inside the fracture...
Effect of DEM resolution in flood modeling: a case study of Gorganrood River, Northeastern Iran
, Article Natural Hazards ; Volume 112, Issue 3 , 2022 , Pages 2673-2693 ; 0921030X (ISSN) ; Ataie Ashtiani, B ; Hosseini, S. M ; Sharif University of Technology
Springer Science and Business Media B.V
2022
Abstract
This study evaluated the efficiency of different Digital Elevation Models (DEMs), including ALOS-12.5 m, SRTM-30 m, SRTM-90 m, and ASTER-30 m v3 when being applied for the hydraulic simulation of flood inundation areas. HEC-RAS-2D model was employed to simulate inundation extent of a 400-year flood (Mar 17, 2019, with peak discharge ~ 547.92 m3/s) along 70 km reach of low-gradient Gorganrood River, northeastern Iran. Fit percentage indicator (FI) and BIAS percentage indicator (BI) were used to evaluate the results in comparison with the remotely sensed inundated area data. The results revealed that the accuracy and capability of the ALOS and SRTM-30 m were higher in simulation of flood...
Theoretical comparative assessment of single- and two-phase models for natural convection heat transfer of Fe3O4/ethylene glycol nanofluid in the presence of electric field
, Article Journal of Thermal Analysis and Calorimetry ; 2020 ; Tavakoli, S ; Pishvaie, M. R ; Sharif University of Technology
Springer Netherlands
2020
Abstract
Natural convective heat transfer of Fe3O4/ethylene glycol nanofluids around the platinum wire as a heater in the absence and presence of the high electric field was investigated, numerically. The control volume finite element method was employed for the numerical simulation. Effects of the flow model, the volume fraction of nanoparticles, Rayleigh number, and the electric field intensity on the natural heat transfer coefficient (NHTC) of nanofluid were studied. Simulation results of single-phase and two-phase flow models showed that the two-phase model could better predict experimental data than the single-phase model due to take into account the velocity of each phase in the mixture. The...