Experimental and CFD simulation of slurry flow in the annular flow path using two-fluid model

, Article Journal of Petroleum Science and Engineering ; Volume 198 , 2021 ; 09204105 (ISSN) Movahedi, H ; Jamshidi, S ; Sharif University of Technology

Elsevier B.V 2021

Abstract

The current study is allocated to experimental evaluation of the multiphase flow of fine solid particles (FSPs) as well as comprehensive numerical study in an annular space under static, laminar, and turbulent flow conditions with consideration of the inner pipe eccentricity and rotation. The experimental investigation was carried out using an annular pipe flow loop. The numerical modeling and simulation of the multiphase flow in the annular space have been performed using the Euler-Euler approach. The unsteady-state multiphase model based on the kinetic theory of granular flow (KTGF) is developed to investigate the particulate flow characteristics in the annular space. Moreover, Standard...

New insight into hydrodynamic and cake erosion mechanism during rotating-disk dynamic microfiltration of concentrated bentonite suspensions at different salinity conditions

, Article Separation and Purification Technology ; Volume 300 , 2022 ; 13835866 (ISSN) Movahedi, H ; Jamshidi, S ; Sharif University of Technology

Elsevier B.V 2022

Abstract

The present study investigates the dynamic filtration of concentrated slurry fluids containing colloidal clay particles under different salinity, shear flow, and flux rate conditions. The dynamic filtration study was carried out by the filtration cell equipped with a rotating disk to apply shear stress over the membrane surface. A 3D CFD simulation has been implemented to model the hydrodynamic flows inside the filtration cell to obtain the wall shear stress (WSS) on the membrane surface at different disk rotation speeds. The thickness and surface patterns of fouling were captured utilizing a surface profilometer. First, the cake-filtration model was used to predict the flux rate and fouling...

Assessment of Seismic Retrofit Policies for Buildings

, M.Sc. Thesis Sharif University of Technology Movahedi, Ali (Author) ; Kashani, Hamed (Supervisor)

Abstract

Occurrence of natural disasters such as earthquake could seriously damage most buildings especially those with insufficient resistance located in urban worn-out textures. In order to reduce unpleasant consequences of an earthquake, appropriate policies need to be considered to persuade the beneficiaries to follow retrofitting standards in the process of planning, designing, and construction of buildings. These policies shall be implemented through institutions in arbitrary or obligatory forms, by encouragement or penalty mechanisms. In order to consider these policies, first of all we need to identify the beneficiaries and their particulars. By studying and considering subjects discussed in...

Simulation and Experimental Study of Permeability Reduction in Porous Media Due to Mud Filtrate Invasion Under Dynamic Conditions

, Ph.D. Dissertation Sharif University of Technology Movahedi, Hamed (Author) ; Jamshidi, Saeed (Supervisor)

Abstract

The reduction of the effective permeability of the reservoir rock in the production area due to various factors is called formation damage. Formation damage is always one of the topics discussed in petroleum engineering. Among the primary and important cases that lead to damage to the formation are the filtration of drilling mud into the production area and the deposition of colloidal particles inside the porous rock during the drilling operation. The length of the productive zone in contact with the drilling fluid usually reaches several hundred feet in Iranian formations. In this study, the aim is to more accurately estimate the amount of permeability reduction caused by the penetration of...

Friction Stir Spot Welding via Consumable Pin

, M.Sc. Thesis Sharif University of Technology Baghdadchi, Amir (Author) ; Movahedi, Mojtaba (Supervisor)

Abstract

Friction stir spot welding (FSSW) as a solid-state process is able to tackle some problems of fusion welding. On the contrary, FSSW has some drawbacks such as the low area of connection and weakness in fatigue behavior. In this study, an innovative method called friction stir spot welding via consumable pin (CP-FSSW) was used, which was able to eliminate the exit-hole. In this process, at the first stage, a hole is created in the center of the overlap area of the sheets; such that the hole is complete in the upper sheet and up to the half thickness of the lower sheet. Then, the rotating tool composed of a consumable pin with diameter length as much as the created hole and same type of the...

Wear Behavior of Al-Fe-Cu Composite Produced by Friction Stir Processing

, M.Sc. Thesis Sharif University of Technology Karimi, Mehran (Author) ; Movahedi, Mojtaba (Supervisor)

Abstract

Composite production is an important method for increasing abrasion resistance in materials. Friction stir processing (FSP) is a solid composite production method which has eliminated the problems of liquid composite production. This research used FSP to study the possibility of in situ production of 1050 aluminum composite with a mixture of copper and iron powder with micrometer sizes of 25-14 and 10 μm, respectively, as reinforcing particles. The following weight percentages of reinforcing powder was added to the sample: 75% iron-25% copper, 50% iron-50% copper and 25% iron-75% copper. In addition, 3 and 5 process passes were considered as another variable in this study. Afterward, the...

Upset Resistance Welding of Duplex Stainless Steel to Martensitic Stainless Steel

, M.Sc. Thesis Sharif University of Technology Ozlati, Ashkan (Author) ; Movahedi, Mojtaba (Supervisor)

Abstract

Upset Resistance Welding (URW) is a solid-state joining process which can be used to join a variety of parts and profiles including railways, wheel rims and pipes used in oil and petrochemical industries. This process has three primary parameters, welding current, current passage time and mechanical pressure. Martensitic Stainless Steels (MSSs) due to high strength and wear resistance, good atmospheric corrosion resistance and relatively low price and Duplex Stainless Steels (DSSs) because of higher strength and better corrosion resistance in chlorine environments, are widely used in different industries. Dissimilar MSS/DSS joints are of great importance for piping, specially in oil and...

, M.Sc. Thesis Sharif University of Technology Shirmohammadi, Davood (Author) ; Movahedi, Mojtaba (Supervisor)

Abstract

Martensitic stainless steels with high strength, good corrosion resistance and formability in the annealed condition are good choices for automotive applications, but they suffer from low weldability due to high hardenability and formation of brittle martensite without tempered structure in the weld metal and heat affected zone (HAZ). In other word, martensitic stainless steels have the worst weldability among all kinds of stainless steels. On the other hand, resistance spot welding is the main method for joining sheets in the automotive industry. Therefore, in the present work, microstructure and mechanical properties of the resistance spot welds of AISI 420 martensitic stainless steel in...

Fusion Welding of Dissolvable Magnesium Alloy

, M.Sc. Thesis Sharif University of Technology Salehi, Mohammad (Author) ; Movahedi, Mojtaba (Supervisor)

Abstract

Magnesium alloys as the lightest structural alloys, have a strong potential for improving the energy efficiency of different transportation systems such as automobiles, aerospace and electronics due to their high strength to weight ratio. Welding plays a crucial role as a foundational manufacturing technology. Hence, the extensive utilization of materials is greatly impacted by their ability to be welded.These alloys are highly susceptible to hot cracking such as liquation cracking during the fusion welding processes.Various mechanisms play a role in the occurrence of hot cracking, but the constitutional liquation of the coarse eutectic mg17al12 intermetallic phase is accountable for the...

Effect of Surface Treatment and Tool Rotational Speed in Aluminum to Polymeric Composite Joint Produced Using Friction Stir/Adhesive Hybrid Process

, M.Sc. Thesis Sharif University of Technology Mohsenirad, Mahtab (Author) ; Movahedi, Mojtaba (Supervisor)

Abstract

Today because of increasing use of fuel, environmental problems and problems due to heavy structures in different industries it is important to use structures with high specific strength. Using different materials in structures like polymers accompanying aluminum could be useful. Polymers are light, heat insulating and have a high corrosion resistance. Polypropylene is one of the useful polymers which can have high impact energy and strength via adding Elastomer and Talc powder, relatively. One of the common ways in joining metal to polymer uses adhesive. It has variety of benefits such as low distortion in joining, different materials joints and having joints with complex geometry. Welding...

Microstructure and Mechanical Properties Investigation of Al-Fe Transition Joints Produced By Additive Manufacturing

, M.Sc. Thesis Sharif University of Technology Ramezani, Habibollah (Author) ; Movahedi, Mojtaba (Supervisor)

Abstract

Joining metal and alloy is a continuous and inevitable effort in oil and gas and automotive industry, and a considerable number of these joints are dissimilar joints. Steels and aluminum alloys are two of the most utilized engineering material and bi-metallic steel-aluminum parts have a lot of applications due to having the combined properties of both alloys (for example the high tensile strength and wear resistance of steels along with good thermal and electrical conductivity and corrosion resistance of aluminum alloys). However, fusion welding of aluminum to steel possesses great challenges due to the difference in melting point, coefficient of thermal expansion, thermal conductivity and...

Welding metallurgy of martensitic advanced high strength steels during resistance spot welding

, Article Science and Technology of Welding and Joining ; Volume 22, Issue 4 , 2017 , Pages 327-335 ; 13621718 (ISSN) Tamizi, M ; Pouranvari, M ; Movahedi, M ; Sharif University of Technology

2017

Abstract

The paper addresses the process–microstructure–performance relationships in resistance spot welding of a martensitic advanced high strength steel. Significant softening was observed in the heat affected zone (HAZ) due to allotriomorphic ferrite formation in the inter-critical HAZ and tempering of martensite in sub-critical HAZ (SCHAZ), with the latter plays more important role in mechanical properties of the spot welds. The strain concentration associated with the HAZ softening promotes initiation of pullout failure from the soft SCHAZ. While, the peak load in the interfacial failure mode is governed by the fusion zone size, that of the pullout mode is significantly affected by the HAZ...

New insight into the filtration control of drilling fluids using a graphene-based nanocomposite under static and dynamic conditions

, Article ACS Sustainable Chemistry and Engineering ; Volume 9, Issue 38 , 2021 , Pages 12844-12857 ; 21680485 (ISSN) Movahedi, H ; Jamshidi, S ; Hajipour, M ; Sharif University of Technology

American Chemical Society 2021

Abstract

During oil and gas well drilling, the filtration control of bentonite water-based drilling fluids (BT-WBDFs), as an environmentally friendly fluid, is crucial to avoid formation damage and swelling shale problems. One of the most critical problems is undesirable changes in the rheology and filtration properties of the BT-WBDFs because of salt contamination. Herein, the potential of using both graphene oxide (GO) nanosheets and a graphene oxide-polyacrylamide (GO-PAM) nanocomposite is evaluated for controlling the filtration properties, especially in a salty medium. First, GO nanosheets were functionalized, and then the GO-PAM nanocomposite was synthesized using the solution polymerization...

Hydrodynamic Analysis and Cake Erosion Properties of a Modified Water-Based Drilling Fluid by a Polyacrylamide/Silica Nanocomposite during Rotating-Disk Dynamic Filtration

, Article ACS Omega ; Volume 7, Issue 48 , 2022 , Pages 44223-44240 ; 24701343 (ISSN) Movahedi, H ; Jamshidi, S ; Hajipour, M ; Sharif University of Technology

American Chemical Society 2022

Abstract

In this study, the potential of using a polyacrylamide-silica nanocomposite (PAM-S) to control the filtration properties of bentonite water-based drilling muds under different salinity conditions was evaluated. Static filtration tests under low-pressure/low-temperature (LPLT) conditions accompanied by rheological measurements have been carried out to analyze the role of silica nanoparticles (NPs) and nanocomposites (NCs) in the base fluid properties. Moreover, high-pressure/high-temperature (HPHT) static filtration was also investigated to evaluate the thermal stability of PAM-S. Afterward, dynamic filtration has been conducted in a filtration cell equipped with an agitating system with a...

Microstructure and mechanical properties of Al/graphite- zirconium oxide hybrid composite fabricated by friction stir processing

, Article Materials Science and Engineering: A ; Volume 862 , 2023 ; 09215093 (ISSN) Keshavarz, H ; Kokabi, A ; Movahedi, M ; Sharif University of Technology

Elsevier Ltd 2023

Abstract

Aluminum matrix surface composites (AMSCs) reinforced by various content of zirconium dioxide (ZrO2) nanoparticles and graphite (Gr) microparticles were fabricated by four passes of friction stir processing (FSP). Processing of composites reinforced by Gr particles did not lead to the sound and well-mixed composites due to a decline in the maximum experienced temperature during the process resulting from the low friction coefficient of graphite particles. Combination of graphite and zirconia particles resulted in a more homogenous dispersion of particles in the stir zone (SZ) due to a higher frictional heat generation and a lower tendency for agglomeration of nanoparticles as compared to...

Investigating the Microstructure and Physical and Mechanical Properties of Composite Lead-Free Solder Containing Ferromagnetic Particles

, M.Sc. Thesis Sharif University of Technology Nourmohammadi, Amir Hossein (Author) ; Movahedi, Mojtaba (Supervisor)

Abstract

The use of tin-lead solder alloys (Pb-Sn) has been limited due to environmental problems in recent years, and several types of research are being carried out on lead-free solder alloys. However, these solders have weaker physical and thermal properties than Pb-Sn solders. In recent years, researchers have been trying to improve these solders' physical and mechanical properties by adding reinforcing particles to the solder and using a magnetic field during melting and solidifying the solder. On the other hand, with the growth path of miniaturization and, simultaneously, compaction and integration of electronic equipment, electronic circuits should have higher current density, better...

Friction Stir Sot Welding of Aluminum to Steel Using Consumable Pin

, M.Sc. Thesis Sharif University of Technology Rafiei, Hamid Reza (Author) ; Movahedi, Mojtaba (Supervisor)

Abstract

Friction Stir Spot Welding as a solid state process is able to solve some of the disadvantages of fusion welding processes. On the other hand, this welding method has disadvantages such as low connection surface due to the hole left by the pin and poor resistance to fatigue loading. In this study, a method called friction stir spot welding via consumable pin was used so that the hole caused by the pin no longer remains at the welding site. The process is done in such a way that first a hole is made in the center of the overlap of the sheets. The rotating tool, in which the consumable pin is made of 6061 aluminum alloy with a diameter equal to the diameter of the hole is lowered at a...

Fabrication of Micron Resolution Polymer Structures with Electrohydrodynamic Printing

, M.Sc. Thesis Sharif University of Technology Shahverdi, Mohammad (Author) ; Movahedi, Mohammad Reza (Supervisor)

Abstract

In recent years, additive manufacturing has been widely used in prototyping and production of industrial-commercial pieces. Additive manufacturing or three-dimensional (3D) printing is able to easily produce any piece for initial prototyping, no matter how complex it is. The fused deposition modeling (FDM) is a type of additive manufacturing process that produces the piece with the mechanism of feeding the PLA filament, then the molten polymer extrusion and depositing the fluid layer by layer with a high viscosity. Since the thickness of the layers is directly proportional to the diameter of the nozzle and the diameter of the used nozzles cannot be in the micron range (lower than 100...

Modeling and Analysis of the Powder Deposition Mechanisms of Selective Laser Sintering Process

, M.Sc. Thesis Sharif University of Technology Shakiba, Abdorreza (Author) ; Movahedi, Mohamad Reza (Supervisor)

Abstract

Selective laser sintering is a technique which uses a laser as the power source to sintering some selected points at a bed of powder in order to create a solid structure. In this research the SLS mechanisms of powder deposition is simulated and surface smoothness and layer density created by each mechanism is computed. For this purpose roller, blade and hopper mechanisms are simulated. For this simulation, polyamide 12 (PA2200) which is a common material is used. In this simulation at first powder specifications are extracted according to the references and for particle shape instead of using the spherical particle shape we use a certain shape that is more close to reality which created by...

Microstructure and Mechanical Properties of Upset Resistance Welds of Al-Mg-Si Alloy Rods

, M.Sc. Thesis Sharif University of Technology Jafari Kandovani, Ali (Author) ; Movahedi, Mojtaba (Supervisor)

Abstract

Alloy 6061 is derived from a combination of aluminum with elements such as magnesium and silicon. Due to its high corrosion resistance, excellent machinability, and high strength, this alloy is widely used in various industries, including aerospace, automotive, and the manufacturing of mechanical parts for airplanes. Butt resistance welding is one type of resistance welding employed for joining various components, such as train rails, construction rebar, automobile rims, as well as in aerospace, petrochemical, and marine industries. Butt resistance welding is a process that can be either fusion-based or solid-state. In this process, similar or dissimilar metals are joined by bringing them to...