Search for: fluid-solid-interaction
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    A parametric study on the effects of surface explosions on buried high pressure gas pipelines

    , Article Engineering Solid Mechanics ; Volume 5, Issue 4 , 2017 , Pages 225-244 ; 22918744 (ISSN) Adibi, O ; Azadi, A ; Farhanieh, B ; Afshin, H ; Sharif University of Technology
    Growing Science  2017
    Underground gas pipelines are one of the vital parts of each country which surface blasts can break down such pipelines, making destructive explosions and threatening the safety of neighborhood structures and people. In this paper, to enhance the safety of these lines, response of a buried 56-inch diameter high pressure natural gas pipeline to a surface blast was numerically investigated. Besides, the effects of: i) explosive mass, ii) pipeline thickness, iii) burial depth and iv) concrete protective layer on pipeline deformation were parametrically studied. To simulate the problem according to actual explosion events, geometries were modeled in real scales, pipeline properties were... 

    Investigation of hydrodynamically dominated membrane rupture, using smoothed particle hydrodynamics–finite element method

    , Article Fluids ; Volume 4, Issue 3 , 2019 ; 23115521 (ISSN) Asadi, H ; Taeibi Rahni, M ; Akbarzadeh, A. M ; Javadi, K ; Ahmadi, G ; Sharif University of Technology
    MDPI AG  2019
    The rupturing process of a membrane, located between two fluids at the center of a three-dimensional channel, is numerically investigated. The smoothed particle hydrodynamics (SPH) and the finite element method (FEM) are used, respectively, for modeling the fluid and solid phases. A range of pressure differences and membrane thicknesses are studied and two different rupturing processes are identified. These processes differ in the time scale of the rupture, the location of the rupture initiation, the level of destruction and the driving mechanism. © 2019 by the authors  

    Numerical modeling of sloshing frequencies in tanks with structure using new presented DQM-BEM technique

    , Article Symmetry ; Volume 12, Issue 4 , 2020 Wei, Z ; Feng, J ; Ghalandari, M ; Maleki, A ; Abdelmalek, Z ; Sharif University of Technology
    MDPI AG  2020
    The sloshing behavior of systems is influenced by different factors related to the liquid level and tank specifications. Different approaches are applicable for the assessment of sloshing behavior in a tank. In this paper, a new numerical model based on the differential quadrature method and boundary element approaches is adopted to investigate the sloshing behavior of a tank with an elastic thin-walled beam. The model is developed based on small slope considerations of the free surface. The main assumption of fluid modeling is homogeneity, isotropy, inviscid, and only limited compressibility of the liquid. Indeed, the formulation is represented based on the reduced-order method and then is... 

    Fluid-solid interaction in electrostatically actuated carbon nanotubes

    , Article Journal of Mechanical Science and Technology ; Vol. 28, issue. 4 , 2014 , p. 1431-1439 Fakhrabadi, M. M. S ; Rastgoo, A ; Ahmadian, M. T ; Sharif University of Technology
    This paper deals with investigation of fluid flow on static and dynamic behaviors of carbon nanotubes under electrostatic actuation. The effects of various fluid parameters including fluid viscosity, velocity, pressure and mass ratio on the deflection and pull-in behaviors of the cantilever and doubly clamped carbon nanotubes are studied. Furthermore, the effects of temperature variation on the static and dynamic pull-in voltages of the doubly clamped carbon nanotubes are reported. The results reveal that altering the fluid parameters significantly changes the mechanical and pull-in behaviors. Hence, the proposed system can be applied properly as a nano fluidic sensor to sense the various... 

    The Study of Flow in Respiratory System with Fluid Structure Interaction Approach

    , M.Sc. Thesis Sharif University of Technology Zendehbad, Mohsen (Author) ; Saeeidi, Mohammad Saeeid (Supervisor)
    In respiratory system of live bodies, different mechanical phenomena such as air suction, diffusion and deposition of particles and transport of species between air and blood take place. Furthermore, the geometry of lung is a complex and multi scale geometry. In order to reduce these complexities, the acinus behavior is transformed to numerical functions which can be used as boundary conditions for simulating upper generations of the lung. Hence, in current study, the air flow suction of the lung is described as a function of the mechanical properties of the lung tissue. This task is fulfilled by modeling the flow for different Elastic moduli and taking fluid structure interaction into... 

    Dynamic and Static Instability of Conical Shells Made of FGM and Conveying Hot Flow

    , M.Sc. Thesis Sharif University of Technology Ekhtiari, Mohsen (Author) ; Haddadpour, Hassan (Supervisor) ; Dehghani Firoozabadi, Rouhollah (Supervisor)
    Static and dynamic instability of truncated conical shells made up of functionally graded materials (FGMs) conveying hot fluid is presented in this paper. Temperature-dependent material properties are considered and Material properties of the truncated FGM conical shells are functionally graded in the thickness direction according to a volume fraction power-law distribution. Governing equation of FGM conical shells is written based on First-Order Shear Deformation Theory (FSDT). The treatment is developed within the theory of linear elasticity, when materials are assumed to be isotropic and inhomogeneous through the thickness direction. The two-constituent functionally graded shell consists... 

    Stability of Atherosclerotic Arteries Using Fluid-structure Interaction

    , M.Sc. Thesis Sharif University of Technology Manzoori, Amir Hossein (Author) ; Fallah, Famida (Supervisor)
    Tortuosity is an abnormality that may occur in some arteries, such as carotid. It can reduce the blood flow to distal organs, and even in severe cases, causes ischemia and stroke. Tortuosity can be congenital or occurs due to hypertension and reduced axial pre-stretch of artery, in which case called buckling. Since atherosclerotic plaques disrupt the normal pattern of blood flow, and thus make the artery more susceptible to buckling, in this study, the effect of atherosclerotic plaques on arterial stability has been investigated using computational simulation of fluid-structure interaction under pulsatile flow and large deformation. Ideal geometry of normal and atherosclerotic carotid artery... 

    Stabilization of the Finite element Analysis of the Fluid-Structure Interaction in Micro Systems in Small Time Steps

    , Ph.D. Dissertation Sharif University of Technology Afrasiab, Hamed (Author) ; Movahhedy, Mohammad Reza (Supervisor) ; Assempour, Ahmad (Supervisor)
    Fluid-structure interaction plays an important role in the performance of various Microsystems. In many micro-devices such as micropumps, microvalves and micromixers, the fluid flow is driven by a vibrating solid membrane. Since the fluid also plays a role in resistance to the solid vibration and deformation, the solid vibration and the fluid flow are always coupled and a full fluid-structure interaction (FSI) analysis is required in order to investigate the performance characteristics of these devices. Since the frequency of the solid vibration is normally high in micro-devices, the time step size required for the finite element analysis of the fluid-structure interaction in these devices... 

    Simulation of Heat Transfer in Nanoscale Flow Using Molecular Dynamics

    , M.Sc. Thesis Sharif University of Technology Abbasi, Hossein Reza (Author) ; Darbandi, Masoud (Supervisor)
    We investigate heat transfer between parallel plates separated by liquid argon using three-dimensional molecular dynamics (MD) simulations incorporating with 6-12 Lennard-Jones potential between molecule pairs. We use thermal walls constructed from the oscillating molecules, which are connected to their original positions using linear spring forces. Channel walls are maintained at specific temperatures using a recently developed interactive thermal wall model. This approach is much more effective than the one which uses a fixed lattice wall modeling to simulate the heat transfer between wall and fluid. Heat flux and temperature distribution in nanochannels are calculated for channel height... 

    Effects of Blood Pressure on Venous Tortuosity and Valves

    , M.Sc. Thesis Sharif University of Technology Mazrooei, Mohammad Amin (Author) ; Fallah Rajabzadeh, Famida (Supervisor)
    Blood vessels are subjected to complex mechanical loads, including internal pressure, external pressure, axial stress due to connection to tissues, and the twist caused by movement of the body. The veins and venous valves, which are responsible for returning blood to the heart, become bent and twisted (tortuosity) for various reasons. This venous tortuosity causes valve insufficiency and changes the hemodynamic pattern of blood flow and varicose veins. Studies show that more than a third of old people suffer from varicose veins. These injuries have made it important to study the physical mechanism of venous tortuosity and the function of venous valves.The purpose of this study is to... 

    Free Vibrations of Elastic Baffled Tanks Containing Sloshing Liquid

    , M.Sc. Thesis Sharif University of Technology Noorian, Mohammad Ali (Author) ; Haddadpour, Hassan (Supervisor)
    In order to study the interaction of sloshing and structural vibrations of baffled tanks a reduced order model based on modal analysis of structure model and boundary element method for fluids motion is developed. For this purpose the governing equations of elastic structure and incompressible flow used to derive simple models to simulate both fields. Using the modal analysis technique the structural motions are applied to the fluid model and on the other hand by using boundary element method the fluid loads are applied to the structural model. Based on this formulation a code is developed which is applicable to an arbitrary elastic tank with arbitrary arrangement of baffles. Results... 

    Vibration Analysis of Dolid-Fluid Interaction to Improve the Aerodynamic Performance of Airfoils with Deflectable Skins

    , M.Sc. Thesis Sharif University of Technology Alami, Nariman (Author) ; Darbandi, Masoud (Supervisor)
    Progress aerodynamic and structural applications has lead to solid-fluid interaction (SFI) engineering. One major application of SFI is to improve of aerodynamic characteristics of airplanes. One option is to use elastic shells.this field of study is so novel and a challenge for future researches. This what current thesis is focused on We use numerical simulation in both fluid and solid parts.In other word, we employ the finite –element method to solve the solid mechanics governing equation and the finite volume element method to treat the fluid dynamics governing equations. The fluid governing equations are 2D navier- stokes equations and the solid part is the 1D Euler – Bernoulli equations... 

    Nonlinear Modelling of Fluid and Solid Interaction in Shells Conveying Fluid Using Combination of FEM and BEM

    , M.Sc. Thesis Sharif University of Technology Khalil Arjomandi, Bahram (Author) ; Haddadpour, Hassan (Supervisor) ; Kord kheili, Ali (Supervisor) ; Dehghani Firouzabadi, Rohollah (Co-Advisor)
    In this M.Sc. thesis dynamics of a system of 3-D fluid (internal) and solid interaction hase been studied. Structure (shell) filled with dense fluid (liquid) and it is under large amplitude vibrations excitations. Shell is analized using geometrical nonlinear general shells formulations. The nonlinear analysis includes large displacements, large rotations and large strains without considering material nonlinearity. Based on the potential flow assumption the governing equations of fluid are derived. And using boundary elements formulations fluid hydrodynamic pressure in each step is drived. In order to simultaneous and mutual influence of fluid and structure, numerical model of combined... 

    Simulation of Fluid-Solid Mixtures Using SPH Method

    , M.Sc. Thesis Sharif University of Technology Hashemi, Mohammad Reza (Author) ; Taghizadeh Manzari, Mehrdad (Supervisor)
    Taghizadeh Manzari, M. (In this work, a modified Smoothed Particle Hydrodynamics (SPH) method, with a new moving solid boundary treatment approach, is utilized to simulate the particulateflow problems. The renormalized first and second derivative schemes which lead tothe consistency of the method, are also used along with a modification to the continuityequation which prevents the spurious pressure oscillations. The proposed methodis validated by solving benchmark problems of solid body motion in channel flows.There is a good agreement between the obtained results and those reported in theliterature. The convergence of solutions for different domain discretizations is alsoassessed. In order... 

    Developing a Compact Finite Difference Method for Solving Fluid - Solid Interaction in Incompressible Flow

    , M.Sc. Thesis Sharif University of Technology Parseh, Kaveh (Author) ; Hejranfar, Kazem (Supervisor)
    In this study, fluid-solid interaction (FSI) is simulated computationally by using a high-order accurate numerical method. The two-dimensional incompressible viscous flows are considered in the fluid domain. The primary problem with solutions of the incompressible Navier–Stokes equations is the difficulty of coupling changes in the velocity field with changes in the pressure field while satisfying the continuity equation. Herein, the artificial compressibility method is used to overcome this difficulty. Preconditioning is implemented to reduce the stiffness of the system of equations to increase the convergence rate of the solution. Using preconditioning, physical solutions even at low... 

    Study the Effect of Considering two Layered wall for Carotid Artery Bifurcation on Distribution of Hemodynamic and Non-Hemodynamic Parameters using a Fluid-Structure Interaction Method

    , M.Sc. Thesis Sharif University of Technology Nikparto, Ali (Author) ; Dehghan Firoozabadi, Bahar (Supervisor) ; Saidi, Mohammad Said (Supervisor)
    It is known today that arterial diseases are among the leading cause of death in modern societies. More than 50% of deaths in western countries are mainly occurred as results of these diseases, namely atherosclerosis. In order to study risk factors and to understand the full process of how arterial diseases initiate and progress, many research topics have been introduced and studied. Researchers believe that mechanical factors such as Wall Shear Stress (WSS), Pressure distribution, Cyclic strain, Back flow zones and many other factors are responsible for initiation of atherosclerosis. Different patterns of Wall Shear Stress and Strain are seen in arteries. Among other factors outlined in... 

    Two-Dimensional Computational Simulation of Fluid-Solid Interaction in Tearing of a Membrane between two liquids with Different Molecular Properties and Pressures, Using SPH Method

    , M.Sc. Thesis Sharif University of Technology Asadi, Hossein (Author) ; Taeibi Rahni, Mohammad (Supervisor) ; Javadi, Khodayar (Supervisor)
    Smoothed particle hydrodynamics (SPH) is a meshfree method, based on Lagrangian formulation of Navier-Stokes equations, in which fluid is discretized to particles. This method is suitable and gives much better results for problems in which other methods have severe difficulties, (e.g., tracking of particles, moving boundaries, and problems with large deformations and, physical discontinuity). No need to follow a regular geometric structure in solution process and simple adaptation and coupling with methods such as finite element, are the positive characteristics of this numerical method. In this work, a systematic study of the processes, which are part of a membrane failure in a... 

    Simulation of the Blood Flow in a Stenotic Left Coronary Bifurcation to Study the Effects on the Endothelial Cells

    , M.Sc. Thesis Sharif University of Technology Jahromi, Reza (Author) ; Saeedi, Mohammad Saeed (Supervisor)
    Morphology and alignment of endothelial cells (ECs) have great influence on plaque formation. These alignments are based on the cyclic strains and wall shear stress (WSS) on the arterial wall. In the present study, cyclic strains and WSS are investigated to predict the secondary plaque locations downstream of the primary stenosis. Therefore, left coronary artery (LCA) with its branches to left anterior descending (LAD) and left circumflex (LCX) are 3D located on a virtual sphere to consider the cardiac motion. Stenoses are placed at the beginning of the bifurcation with varying degrees from 40% to 70% based on diameter reduction. Healthy coronary is also constructed to compare with those of... 

    Numerical Study of Margination and Adhesion of Micro- and Nano-particles in Coronary Circulation

    , M.Sc. Thesis Sharif University of Technology Forouzandehmehr, Mohammad Amin (Author) ; Shamloo, Amir (Supervisor)
    Obstruction of Left Anterior Descending artery (LAD) due to thrombosis or atherosclerotic plaques is the leading cause of death world–wide. Targeted delivery of drugs through micro- Nano-particles holds noteworthy promise which can make clot busting or the restenosis treatment with minimal toxicity possible. In this work, Fluid-Structure Interaction (FSI) simulations of blood flow through a patient-specific reconstructed geometry of LAD artery have been conducted using a non-Newtonian hematocrit (HCT) dependent model for blood. Based on physiological facts, 25, 45 and 65 percentages of HCT were assumed as acceptable representations of anemic, healthy and diabetic blood conditions,... 

    Modeling and Experimental Study of Gas Reservoir Formation Damage Caused by Solid-based Drilling Fluids

    , M.Sc. Thesis Sharif University of Technology Vasheghani Farahani, Mehrdad (Author) ; Jamshidi, Saeed (Supervisor)
    Nowadays, one of the most challenges in drilling and production engineering, is the formation damage caused by fluid filtration while drilling and completion operations. This damage would cause serious problems in pay zone and besides influencing the well performance during its life time – due to permeability reduction in near wellbore area- and cause economic expenses such as workover and stimulation operation. Therefore, considering the aspects of formation damage minimization during drilling and completion operations, the fluid selection for these purposes would be crucial. It requires the knowledge of interactions between these fluids and the reservoir rock. In this thesis, using the...