Sharif Digital Repository

Problems with the mitral valve can make the heart less efficient at pumping blood around the body. Severe problems can lead to heart failure if the valve is not surgically repaired or replaced. A simple approximation of the heart geometry is used and the valve dimensions are based on reported measurements. The primary objective for this study is to design and simulate the opening and closing behavior of the mitral valve using 2D fluid-structure interaction (FSI) model using ADINA software in order to evaluate and investigate the hemodynamic performance and problems of mitral valve, in which the blood is described as a viscous incompressible fluid, and the mitral valve is described as an... 

Insulin pump treatment is considered the most physiological way to imitate the healthy body's insulin profile in patients with diabetes. They provide a precisely controlled rate of insulin delivery to diabetic patients who would normally need multiple daily injections to regulate blood glucose levels. The firmware allows numerous modifications to the bolus dose and basal rate to enable patients to manage insulin levels in response to events such as eating, sleeping, and exercise.
In this Study, we have first investigated different models of insulin pumps on the market and chose the Spring ZoneTM insulin pump model for our study due to its innovative technology. This pump employs a... 

Vibration is one of the major problems in gas and oil pipelines. Vibrations can cause damage to the pipes, supports, valves and other equipment installed in the system. These vibrations can be caused by equipment installed on pipelines like compressors and pumps or by fluid flow in pipes and fixed equipment like connections and valves. This research investigates the dynamic behavior of fluid flow in pipelines in Karanj and Parsi oil fields located in the southern part of Iran. The pipeline is responsible for injecting gas into the field. Excessive vibrations in the system cause repeatable damage which in turn increases the operating and maintenance cost. First, the vibration of pipelines has... 

Recent decades have seen a growing demand for high-power wind turbines resulting in turbines with larger blades and the advent of high-megawatt wind turbines. The blades of the megawatt-scale turbines experience more complicated flow phenomena compared to those of the smaller-scale wind turbines. Needless to say, the importance of an accurate solution and detailed analysis of all the parameters, including blades aerodynamic and aeroelastic performance as well as fluid-structure interaction, is more significant for the megawatt-scale turbines compared to smaller-scale turbines. The conventional methods of aerodynamic solutions for the blade, including analytical methods, such as BEMT78 and... 

At high speeds, cavitation bubbles form at the sharp edges of the submerged body or in situations where the pressure falls below the fluid vapor pressure. By placing a suitable cavitator in the nose of the body, the cavitation bubbles are cobined by increasing the speed and the whole body is placed inside the cavity. The formation of a supercavity leads to a significant reduction in the drag force of the vehicle. The submersible device is in contact with the fluid at two points, the cavitator and the fins, and due to the location of the cavitator in the nose of the body, the forces acting on it play an important role in the stability and control of the device.The main goal of current... 

In this study, stability as well as linear and nonlinear vibrations of coaxial rotating cylindrical shells conveying annular incompressible fluid medium are investigated. To this aim the inner isotropic and elastic rotating cylindrical shell along with the rigid and stationary outer cylinder are considered. Equations of motion for the inner cylinder are determined according to the Hamilton’s principle and using the Sanders-Koiter theory assumptions. In order to generalize the boundary condition implementation, some translational and rotational springs are attached to the boundaries at the mid-plane. The final system of equations are solved by means of the extended Galerkin method – being an... 

The goal of this thesis is the development and application of the finite volume method (FVM) with a same solution procedure in the fluid and structure domains for the simulation of fluid-structure interaction (FSI) problems in the compressible fluid flow. The unsteady Euler equations written in the arbitrary Lagrangian–Eulerian (ALE) form are considered as the governing equations of the compressible fluid flow and the moderate/large nonlinear deformation of the elastic structure is considered to be governed by the Cauchy equations in the Lagrangian/total Lagrangian forms. Therefore, the nonlinear phenomena in the unsteady compressible fluid flow and the large deformation of the elastic... 

The issue of solid and fluid interaction in horizontal axis wind turbines with diameter of more than 120 meters is one of the most important researching subjects of this type of turbines. This issues needs quick and exact solutions because of the high computational cost of fluid and structural domains.In this research a quick method with acceptable accuracy has been suggested which is based on computational fluid dynamic to examine the aeroelastic behavior of rotor and wind turbine tower. The actuator disc method in two domains of axisymmetric and three-dimensional has been used to compute aerodynamic forces. For this purpose a code has been written in C++ to set down virtual momentum on... 

In the present study, the numerical simulation of the panel flutter in compressible inviscid flow is performed by the compact finite difference method. For this purpose, the 2D compressible Euler equations written in the arbitrary Lagrange-Eulerian form are considered and the resulting system of equations in the generalized curvilinear coordinates is solved by the fourth-order compact finite-difference method. An appropriate nonlinear filter is applied for the shock capturing and for the solution to be stable. The governing equation for the panel is also numerically solved by using the fourth-order compact finite difference method. The time integration in the flow domain is made by the... 

In the current study, nonlinear vibration and stability of conical shells with both separate and concurrent internal and external flows are studied. External and internal flows are in the supersonic and subsonic regimes, respectively. The Krumhar’s aerodynamic piston theory is utilized to model the external loading on the structure as well as the compressible potential flow model to capture the internal fluid dynamics. The so-called compressible fluid model is obtained via simplification of the Navier-Stockes equations after applying the inviscid and irrotational assumptions. The nonlinear structural equations of motion are derived using the Hamiltonian dynamics approach and utilizing the... 

In this thesis, the dynamic behavior of a pinned-pinned fractional viscoelastic pipe conveying fluid is examined in the external cross flow. The Galerkin method is employed to discretize the nonlinear coupled equations of motion for viscoelastic pipe conveying fluid in the external cross flow. Consequently, four modes of system are obtained. In addition, direct perturbation method of multiple scale is used to solve the governing nonlinear coupled equations of motion for the fractional viscoelastic pipe conveying pulsating fluid in the external cross flow. Moreover, time response diagrams are drawn in order to investigate under effects of the internal fluid velocity, external fluid reduced... 

Human body is subjected to body accelerations or vibrations in several circumstances. During gravitational changes, the hydrostatic pressure gradient along the body axis changes, and then body fluids are redistributed. Prolonged exposure to high level external acceleration may lead to serious or even fatal situations on account of disturbances in blood flow. Due to physiological importance of body acceleration many theoretical investigations have been carried out for the flow of blood under the influence of body acceleration. In this study, the mechanical loads that pilots experience during flight are considered. The aim of the present study is to investigate the effects of mechanical... 

The fluid structure interaction (FSI) problems are widely encountered in many industrial applications in mechanical, aerospace, biomedical, marine, and wind engineering. The main contributions of this research are focused on simulating flow with moving or deforming boundaries including FSI problems with large movement or deformations. In this regard, a hybrid finite-element-volume (FEV) method was used in an arbitrary Lagrangian-Eulerian (ALE) framework. In this research, a new layer-by-layer mesh movement strategy was developed to perform the unstructured grid movement more robustly. This strategy converts the complex data structure of an unstructured grid to a simple quasi-structured data... 

In the present project an analytical model is proposed for the instability of spinning composite cylindrical shells partially filled with fluid. For this purpose, using the linearized Navier-Stokes equation for the incompressible flow, a 2-D model is developed for fluid motion at each section of the cylinder. The resultant pressure exerted on the cylinder wall as the result of the fluid motion, are calculated in terms of elastic displacements of the cylinder. Applying the Hamilton principle, the governing equations of motion of the cylinder are derived and then combined with the equations describing the fluid pressure to obtain the coupled-field equations of the structural-fluid motion.... 

This M.Sc thesis aims at studding system of fluid and solid interaction. Based on the potential flow assumption along with using the perturbation technique, the governing kinematic and dynamic boundary conditions of the first- and second-order velocity potential are derived. Then, a boundary element model is developed for the sloshing dynamics which is formulated in terms of the velocity potential of the liquid free-surface. The boundary element model is used to determine the natural mode shapes of sloshing and their corresponding frequencies. Using the modal analysis technique, a nonlinear model is represented for calculation of the first- and second-order potential which can be used to... 

This thesis deals with developing and applying reduced order modeling techniques for fluid and structure interaction problems. First, the basis and formulations of reduced order modeling technique in the function space are reviewed. Then the governing equations of structural dynamics as well as incompressible flow are reviewed and some simplifications are applied. Based on the modal analysis technique along with the finite element model of the structure and the boundary element model for flow field, some reduced order models are represented. The represented models are developed for liquid sloshing in moving and elastic tanks, fluid structure interaction in flexible shells conveying flow,... 

The objective of this research is to investigate the use of passive control system to reduce the seismic response of fixed-roof, above-ground, cylindrical steel tanks as well as to decrease the damage caused to these structures in the event of an earthquake. The most crucial step for a safe design in this case is determining the lateral forces due to earthquake with sufficient accuracy; These forces are eventually resisted by the storage tank walls and the supports. Determining analiytical solution to the problem is not possible due to the interaction of the liquid with the structure. Therefore, numerical approach was adopted to determine the response of the tank using ANSYS program. Two... 

The importance of the liquid storage tanks in this era is as much as their contained liquid that we use in our daily lives. Many studies have been carried out on these influential structures considering various aspects. The major damages inflicted to the liquid storage tanks in Loma Prieta, Lozan, Hokaido, Arzinkan, Northridge, Kobe, Izmit & Haiti Earthquakes, has led the researchers to perform various experimental and analytical studies on this regard in the last few decades. The most important part of a safe design of a storage tank is the accurate estimation of the seismically induced lateral forces that should be transferred to its base through the tank shell and its support. Moreover,... 

The circular flexible cylindrical liquid tanks are usually made of steel or aluminum and in majority of cases are built on grade due to its economic advantages. The most important part of a safe design of storage tanks is the accurate estimation of the seismically induced lateral forces that should be transformed to its base through the tank shell and its support . seismic behavior of the liquid storage tank is quite different from regular buildings industrial structures due to its nonlinear behavior caused by complex distribution of hydrodynamic pressure, buckling of its wall, etc.. moreover, the effect of rocking motion caused by under laying soft soil, on its response parameter could be... 

The circular flexible cylindrical liquid tanks usually are made of steel or aluminum and in majority of cases are built on grade due to its economic advantages. The most important part of a safe design of a storage tanks is the accurate estimation of the seismically induced lateral forces that should be transferred to its base through the tank shell and its support. Seismic behavior of liquid storage tanks is quite different from regular buildings and industrial structures due to its nonlinear behavior caused by complex distribution of hydrodynamic pressure, buckling of its walls, etc.. Moreover, the effect of rocking motion caused by the under laying soft soil, on its response parameters...