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Numerical Simulation Of Pulsatile Blood Flow Across A Tilting Disk Mechanical Heart Valve
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Book Synopsis Numerical Simulation of Pulsatile Blood Flow Across a Tilting-disk Mechanical Heart Valve by : Alireza Nejadmalayeri
Download or read book Numerical Simulation of Pulsatile Blood Flow Across a Tilting-disk Mechanical Heart Valve written by Alireza Nejadmalayeri and published by . This book was released on 2007 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Numerical and Experimental Investigations of Pulsatile Blood Flow Through a Dysfunctional Mechanical Heart Valve by : Othman Ahmed Smadi
Download or read book Numerical and Experimental Investigations of Pulsatile Blood Flow Through a Dysfunctional Mechanical Heart Valve written by Othman Ahmed Smadi and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Dynamic Simulation of Tilting-Disc Mechanical Heart Valve in Pulsatile Flow by : 徐子圭
Download or read book Dynamic Simulation of Tilting-Disc Mechanical Heart Valve in Pulsatile Flow written by 徐子圭 and published by . This book was released on 2006 with total page 113 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Numerical Simulation of Fluid-structure Interaction for Tilting-disk Mechanical Heart Valves by : Ardavan Aliabadi
Download or read book Numerical Simulation of Fluid-structure Interaction for Tilting-disk Mechanical Heart Valves written by Ardavan Aliabadi and published by . This book was released on 2013 with total page 81 pages. Available in PDF, EPUB and Kindle. Book excerpt: According to the United States Department of Health and Human Services, 27.1 million non-institutionalized adults were diagnosed with heart disease in 2010. The number of deaths associated with heart disease in 2009 was reported to be 599,413, claiming the lives of 195 out of every 100,000 people, which makes heart disease the number one killer in the U.S. Even though mechanical heart valves (MHVs) have proven to save lives in many of these cases, they are still not perfect, and complications arising from their design have reduced their application. To better understand the important factors and pursue remedies, numerous experimental investigations have been conducted; however, despite impressive improvements, small-scale studies suffer from lower levels of accuracy and sometimes are very costly to conduct. As in many other areas of research, numerical simulations can be helpful in reducing costs and supplementing such experimental work. The computational effort in this thesis focused on the numerical analysis of current tilting-disk MHVs. In this work, an implicit fluid-structure interaction (FSI) simulation of the Bjork-Shiley design was carried out using in-house codes implemented in the commercial code software FLUENT. In-house codes in the form of journal files, schemes, and user-defined functions (UDFs) were integrated to automate the inner iterations and enable communication between the fluid and the moving disk at the interfaces. Based on the investigation of the current simulations, a new design aiming at improving the hemodynamic performance is suggested. The hemodynamics of flow in current tilting-disk valves was compared with the suggested design, and it is concluded that the suggested design has a better hemodynamic performance in terms of shear stress values and residence times.
Book Synopsis Numerical Simulation of the Leaflet Designs to Improve Hemodynamics of Mechanical Heart Valves by : Omid Sirous
Download or read book Numerical Simulation of the Leaflet Designs to Improve Hemodynamics of Mechanical Heart Valves written by Omid Sirous and published by . This book was released on 2017 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mechanical heart valves (MHVs) are widely implanted due to their reliability and long life span. However, patients who receive MHV implants are required and prescribed anticoagulant medication to reduce the high risk of thromboembolic complications. Although MHVs are considered as a long-term devices to save the lives of thousands of patients suffering from severe heart valve diseases, current designs could be improved based on the fundamentals of fluid mechanics in order to overcome some of the serious complications that can threaten the lives of patients, as well as improve the quality of their lives. Non-physiological blood flow and a higher level of mechanical stresses endured by the blood cells are considered as possible elements of those complications. It is believed that due to the non-physiological blood flow field through the MHVs, leaflet(s) motion can induce thromboembolism and also embolic strokes. The influence of higher levels of mechanical shear stresses, exposure time, and static flow zones behind the leaflet(s) cause significant effects to elevate platelet activation and thromboembolism formation. This research is an effort to provide further information regarding the capability of the passive flow management techniques to reduce these complications, and therefore improve the hemodynamic characteristics of blood flow to prevent high shear stress zones and blood cell damage. The objective of the current research activities is an attempt to examine pulsatile blood flow through MHVs with modified designs. In this investigation, we aim to investigate the effect of the valves with porous leaflets and compare the proposed design with the basic leaflet design. A set of steady and transient 3-dimensional models of MHVs with pulsatile, non-Newtonian turbulent blood flow were developed and investigated in order to: (1) numerically analyze the result of passive flow control techniques, (2) improve the hemodynamics of the valve, and (3) reduce the excessive levels of mechanical stresses compared to the basic bileaflet MHV. The computational models show a distinct difference in the flow field in the two designs, both of which demonstrate significant improvements in the hemodynamics of MHV.
Book Synopsis Numerical Simulation of Steady and Pulsatile Flow Through Models of Vascular and Aortic Valve Stenoses by : Emmanuel Chima Okpara
Download or read book Numerical Simulation of Steady and Pulsatile Flow Through Models of Vascular and Aortic Valve Stenoses written by Emmanuel Chima Okpara and published by . This book was released on 2004 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Modelling of Blood Flow Through Mechanical Heart Valves Using Large Eddy Simulation [microform] by : Masroor Mansoor Chaudhri
Download or read book Modelling of Blood Flow Through Mechanical Heart Valves Using Large Eddy Simulation [microform] written by Masroor Mansoor Chaudhri and published by Library and Archives Canada = Bibliothèque et Archives Canada. This book was released on 2004 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt: A majority of heart valve replacement procedures use bi-leaflet mechanical heart valves (MHV). Although these valves function adequately, they require constant anticoagulant therapy to prevent thrombus (clot) formation. Thrombus formation is primarily due to platelet activation, which is caused by nonphysiological flow conditions through MHVs. Blood flow in MHVs can be turbulent, and thus there is a need to better understand both laminar and turbulent flow through MHVs. In this work, a code for the solution of the two-dimensional Navier-Stokes equations has been extended to include the Streamline Upwind/Petrov Galerkin (SUPG) method and Large Eddy Simulation (LES) for modelling turbulent flows using the constant co-efficient Smagorinsky model. Different numerical tests have been performed to evaluate the validity of the numerical code. Results from the unsteady turbulent simulation agree qualitatively with computational and experimental studies, indicating that turbulence affects the flow field in the vicinity of the heart valve and should be addressed when modelling blood flow in MHVs.
Book Synopsis Numerical Simulation of Flow Through an Artificial Heart by :
Download or read book Numerical Simulation of Flow Through an Artificial Heart written by and published by . This book was released on 1989 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Analysis and Simulation of Blood Flow Through a Mechanical Heart Valve by : Min Zhou (M.S.)
Download or read book Analysis and Simulation of Blood Flow Through a Mechanical Heart Valve written by Min Zhou (M.S.) and published by . This book was released on 2005 with total page 340 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Numerical Modeling of Blood Flow in Prosthetic Heart Valves and Cardiovascular Pathologies by : Yared Alemu
Download or read book Numerical Modeling of Blood Flow in Prosthetic Heart Valves and Cardiovascular Pathologies written by Yared Alemu and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Blood Flow Dynamics Through a Defective Mechanical Heart Valve by : Othman Smadi
Download or read book Blood Flow Dynamics Through a Defective Mechanical Heart Valve written by Othman Smadi and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Image-Based Computational Modeling of the Human Circulatory and Pulmonary Systems by : Krishnan B. Chandran
Download or read book Image-Based Computational Modeling of the Human Circulatory and Pulmonary Systems written by Krishnan B. Chandran and published by Springer Science & Business Media. This book was released on 2010-11-18 with total page 474 pages. Available in PDF, EPUB and Kindle. Book excerpt: Image-Based Computational Modeling of the Human Circulatory and Pulmonary Systems provides an overview of the current modeling methods and applications enhancing interventional treatments and computer-aided surgery. A detailed description of the techniques behind image acquisition, processing and three-dimensional reconstruction are included. Techniques for the computational simulation of solid and fluid mechanics and structure interaction are also discussed, in addition to various cardiovascular and pulmonary applications. Engineers and researchers involved with image processing and computational modeling of human organ systems will find this a valuable reference.
Book Synopsis Numerical Simulations of the Micro Flow Field in the Hinge Region of Bileaflet Mechanical Heart Valves by : Helene Anne Simon
Download or read book Numerical Simulations of the Micro Flow Field in the Hinge Region of Bileaflet Mechanical Heart Valves written by Helene Anne Simon and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Native heart valves with limited functionality are commonly replaced by a bileaflet mechanical heart valve (BMHV). However, despite their widespread use, BMHVs still cause major complications, including hemolysis, platelet activation, and thromboembolic events. These complications are believed to be due to the non-physiologic hemodynamic stresses imposed on blood elements by the hinge flows. Three-dimensional characterization of the hinge flows is therefore crucial to ultimately design BMHVs with lower complication rates. This study aims at simulating the pulsatile 3D hinge flows of various BMHVs placed and estimating the thromboembolic potential associated with each hinge. The hinge and leaflet geometries of clinical BMHVs are reconstructed from micro-computed tomography scans. Simulations are conducted using a Cartesian sharp-interface immersed-boundary methodology combined with a second-order accurate fractional-step method. Physiologic flow boundary conditions and leaflet motion are extracted from the Fluid-Structure-Interaction simulations of the BMHV bulk flow. The accuracy of the solver is assessed by comparing the results with experimental data. The numerical results are analyzed using a particle tracking approach coupled with existing blood damage models to relate the flow structures to the risk for blood damage.
Book Synopsis Numerical Simulation of Blood Flow in the Stenotic Carotid Bifurcation by : Vitaliy Lvovich Rayz
Download or read book Numerical Simulation of Blood Flow in the Stenotic Carotid Bifurcation written by Vitaliy Lvovich Rayz and published by . This book was released on 2005 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Direct Numerical Simulations of Flow Inside a Bileaflet Mechanical Heart Valve by : Antonio Cristallo
Download or read book Direct Numerical Simulations of Flow Inside a Bileaflet Mechanical Heart Valve written by Antonio Cristallo and published by . This book was released on 2006 with total page 105 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis A Simulation Model of Pulsatile Blood Flow in Elastic and Viscoelastic Arteries by : Warriner Renee K.
Download or read book A Simulation Model of Pulsatile Blood Flow in Elastic and Viscoelastic Arteries written by Warriner Renee K. and published by . This book was released on 2006 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: A simulation model of pulsatile blood flow within rigid, elastic, and viscoelastic arteries was developed. The simulation system was based upon the analytical solution proposed by Womersley (1957) and validated through comparison with an extensive set of published in vivo and numerical simulation data of the human common carotid artery. The model takes as input, a pressure, pressure gradient, or volumetric flow rate waveform of a single cardiac cycle. System outputs include the pressure, pressure gradient, radial and longitudinal fluid velocities, radial and longitudinal arterial wall displacements, volumetric flow rate, average longitudinal velocity, and shear stress. It was concluded that longitudinal wall displacement is significant and should be considered when quantifying wall movement. Both the elastic and viscoelastic arterial wall models are consistent with results obtained in the literature. However, the viscoelastic model is preferred as it can account for observed phase delays between the pressure and radial wall displacement.
Book Synopsis Numerical Simulation of Blood Flow in Arterial Stenosis Under Steady and Pulsatile Flow Conditions by : Parth Pranavbhai Dave
Download or read book Numerical Simulation of Blood Flow in Arterial Stenosis Under Steady and Pulsatile Flow Conditions written by Parth Pranavbhai Dave and published by . This book was released on 2011 with total page 105 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
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