Numerical Simulation Of Blood Flow In Arterial Stenosis Under Steady And Pulsatile Flow Conditions
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Numerical Simulation Of Blood Flow In Arterial Stenosis Under Steady And Pulsatile Flow Conditions
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Author : Parth Pranavbhai Dave
language : en
Publisher:
Release Date : 2011
Numerical Simulation Of Blood Flow In Arterial Stenosis Under Steady And Pulsatile Flow Conditions written by Parth Pranavbhai Dave and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with Electronic dissertations categories.
Cardiovascular diseases (CVDs) are among the leading causes of death in the world. In this study, an attempt was made to model the flow dynamics of blood in abnormally narrowed artery. Finite volume solver FLUENT was used for the analysis with the aim of understanding the consequences of increasing the degree of stenosis using a two-equation turbulence model. The compliant nature of the artery was neglected, and Newtonian behavior of the blood flow was assumed for the larger arteries. Steady-flow simulations with 75% area reductions were used to establish the validity of the current models by employing the standard and transitional variant of the k -w turbulence models. Subsequently, it was found that transitional k -w model was suitable for the low Reynolds number internal flows associated with the transition to turbulence, although only a minor departure in terms of the turbulence intensity peak was observed. Unsteady blood flow was introduced by employing a sinusoidal pulsatile waveform at the inlet. The pulsatile nature of the blood flow was investigated in the range of the constriction ratio from 60% to 90%, with an inlet-specified pulse. It was hypothesized that the severity of the stenosis played a major role in the initiation of the turbulence, since no major turbulence was reported for the 60% and 75% area reductions, while increasing the constriction ratio of 90% significantly altered the flow dynamics and triggered the transition to turbulence much earlier than anticipated. The outcome of current numerical efforts was expressed in terms of wall shear stress, a hemodynamically relevant parameter.
Numerical Simulation Of Blood Flow In The Stenotic Carotid Artery Bifurcation
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Author : Jennifer Sara Stroud
language : en
Publisher:
Release Date : 2000
Numerical Simulation Of Blood Flow In The Stenotic Carotid Artery Bifurcation written by Jennifer Sara Stroud and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2000 with categories.
Numerical Simulation Of Blood Flow In The Stenotic Carotid Bifurcation
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Author : Vitaliy Lvovich Rayz
language : en
Publisher:
Release Date : 2005
Numerical Simulation Of Blood Flow In The Stenotic Carotid Bifurcation written by Vitaliy Lvovich Rayz and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2005 with categories.
Les Of Pulsatile Flow In The Models Of Arterial Stenosis And Aneurysm
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Author : Md Mamun Molla
language : en
Publisher:
Release Date : 2009
Les Of Pulsatile Flow In The Models Of Arterial Stenosis And Aneurysm written by Md Mamun Molla and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with categories.
The Large Eddy Simulation (LES) technique is used to simulate the different types of Newtonian and non-Newtonian pulsatile blood flow in a constricted as well as in a dilated channel to gain insight of the transition-to-turbulent blood flow due to the arterial stenosis and aneurysm. In the stenosed model, a cosine shape stenosis is placed at the upper wall of a 3D channel which reduces the cross-sectional area, whereas the aneurysm which is also placed at the upper wall dilates the channel cross-sectional area. In LES, a top-hat spatial grid-filter is applied to the Navier-Stokes equations of motion to separate the large scale flows, which carry the majority of the energy, from the small scale known as sub-grid scale (SGS). The large scale flows are resolved fully while the unresolved SGS motions are modelled using two different dynamic models to determine the Smagorinsky constant at each time step. Initially, an additive sinusoidal pulsatile velocity profile is used at the inlet of the model stenosis to generate the unsteady oscillating flow and a comparison is made between the results obtained by the additive and non-additive pulsation. Secondly, the physiological pulsatile flow in the same model stenosis is investigated, where the physiological pulsation is generated at the inlet using the first four harmonics of the Fourier series of pressure pulse. A comparison between the LES and the coarse Direct Numerical Simulation (DNS) results is drawn and the effects of the various harmonics of pressure pulse, length and percentage of the stenosis on the flow field are examined. Transition-to-turbulent physiological flow through the model of a double stenosis and an aneurysm is also investigated. Finally, the physiological pulsatile flow in a model of single stenosis is investigated using the various non-Newtonian blood viscosity models and the results are compared with the Newtonian model. For the additive sinusoidal pulsation case the maximum ratio of the SGS to molecular viscosity is 0.709 and for the non-additive case is 0.78 while Re=2000. The shape of the post-stenotic re-circulation region is totally different between the additive and non-additive case. In the additive case the upper wall pressure drop is larger than the non-additive case. Due to the large amplitude of the oscillation, transition happens earlier and the peak turbulent kinetic energy occurs at the post-lip of the stenosis. The intensity of the turbulent kinetic energy is higher in the additive sinusoidal pulsation case than the physiological pulsation. The maximum contribution of the SGS motion to the large-scale motion is 37.4% for the first harmonic physiological pulsation while 97% contribution from the first four harmonics case for Re=2000. The centre line turbulent kinetic energy is slightly higher in the first harmonic case than the first four harmonics. For the higher area reduction of the stenosis, the stress drop at the upper wall, the maximum shear stress at the lower wall and the turbulent kinetic energy increased. The intensity of the shear stress and the turbulent kinetic energy decreased when the length of the stenosis is increased. The break frequency of the energy spectra found from -5/3 to -10/3 for the velocity fluctuations and from -5/3 to -7/3 for the pressure fluctuations. Due to the presence of the second stenosis, the stress drop, the adverse pressure gradient and the turbulent intensity of the flow enhance significantly. Inside the aneurysm a large re-circulation region exists and the flow is turbulent for a asymmetric aneurysm and maximum turbulent intensity occurs between the centre and the ending segment of the aneurysm. Owing to the effects of the non-Newtonian viscosity, the length of the post-stenotic re-circulation region increased as well as the streamwise velocity and the turbulent kinetic energy decreased.
Numerical Simulation Of Steady And Pulsatile Flow Through Models Of Vascular And Aortic Valve Stenoses
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Author : Emmanuel Chima Okpara
language : en
Publisher:
Release Date : 2004
Numerical Simulation Of Steady And Pulsatile Flow Through Models Of Vascular And Aortic Valve Stenoses written by Emmanuel Chima Okpara and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2004 with categories.
Numerical Simulation Of Pulsatile Blood Flow Across A Tilting Disk Mechanical Heart Valve
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Author : Alireza Nejadmalayeri
language : en
Publisher:
Release Date : 2007
Numerical Simulation Of Pulsatile Blood Flow Across A Tilting Disk Mechanical Heart Valve written by Alireza Nejadmalayeri and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007 with Electronic dissertations categories.
To overcome several clinical challenges involving mechanical heart valves, accurate numerical simulation of blood flow through these devices has been of interest. Since heart disease is the leading cause of death around the world, the hemodynamic study of the heart is of extraordinary interest in the field of bio fluid dynamics. Recent numerical/experimental investigations have shown that mechanical heart valves inherit the "production of sufficiently large shear and turbulent stresses to cause clinical problems such as hemolysis." Due to several parameters including the non-Newtonian behavior of blood, pulsatile waveform, strong blood and tissue interactions, clinical difficulties, etc., experimental examination of blood flow in the heart and its valves is a very difficult task. Therefore, comprehensive numerical analysis of this complex fluid-structure system is essential. However, precise experimental investigations are still imperative for developing appropriate and accurate turbulence models and for validating numerical techniques.In the current computational effort, the first set of objectives was numerical investigations of vortex shedding behind a two-dimensional tilting-disk mechanical heart valve in a straight channel, which is a simplified representation of the mitral position, using first- and several higher-order finite volume schemes as well as examination of the non-Newtonian viscosity effects on shedding frequency and amplitude.
Haemodynamics Of Arterial Organs
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Author : X. Y. Xu
language : en
Publisher: WIT Press (UK)
Release Date : 1999
Haemodynamics Of Arterial Organs written by X. Y. Xu and has been published by WIT Press (UK) this book supported file pdf, txt, epub, kindle and other format this book has been release on 1999 with Medical categories.
Partial Contents: Haemodynamics of the Reconstruction of Complex Cardiac Malformations; Simulation of Time-Dependent Blood Flow Past Valve Prostheses; Comparisons between Computational Haemodynamics, Photochromic Dye Flow Visualisation and Magnetic Resonance Velocimetry.
Numerical Simulation Of Blood Flow In Arteries
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Author : Thomas Fundi Rutaganira
language : en
Publisher:
Release Date : 1997
Numerical Simulation Of Blood Flow In Arteries written by Thomas Fundi Rutaganira and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1997 with categories.
Numerical Simulation Of Steady And Pulsatile Flow In Stenosed Tapered Artery And Abdominal Aortic Aneurysm Using Model
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Author : Chiragkumar D.. Tala
language : en
Publisher:
Release Date : 2010
Numerical Simulation Of Steady And Pulsatile Flow In Stenosed Tapered Artery And Abdominal Aortic Aneurysm Using Model written by Chiragkumar D.. Tala and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with Electronic dissertations categories.
Numerical Simulations Of Blood Flow Through The Carotid Artery Bifurcation
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Author : Liang-Der Jou
language : en
Publisher:
Release Date : 1995
Numerical Simulations Of Blood Flow Through The Carotid Artery Bifurcation written by Liang-Der Jou and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1995 with categories.