A NUMERICAL STUDY ON THE HEMODYNAMIC AND SHEAR STRESS OF DOUBLE ANEURYSM THROUGH S-SHAPED VESSEL

2015 ◽  
Vol 27 (04) ◽  
pp. 1550033 ◽  
Author(s):  
Mahdi Halabian ◽  
Alireza Karimi ◽  
Borhan Beigzadeh ◽  
Mahdi Navidbakhsh
Keyword(s):  
Blood Flow ◽  
Mechanical Behavior ◽  
Numerical Study ◽  
Flow Characteristics ◽  
Flow Simulation ◽  
The Body ◽  
Sweep Angle ◽  
Abdominal Aortic ◽  
Hemodynamic Characteristics ◽  
Refined Meshes

Abdominal aortic aneurysm (AAA) is a degenerative disease defined as the abnormal ballooning of the abdominal aorta (AA) wall which is usually caused by atherosclerosis. The aneurysm grows larger and eventually ruptures if it is not diagnosed and treated. Aneurysms occur mostly in the aorta, the main artery of the chest and abdomen. The aorta carries blood flow from the heart to all parts of the body, including the vital organs, the legs, and feet. The objective of the present study is to investigate the combined effects of aneurysm and curvature on flow characteristics in S-shaped bends with sweep angle of 90° at Reynolds number of 900. The fluid mechanics of blood flow in a curved artery with abnormal aortic is studied through a mathematical analysis and employing Cosmos flow simulation. Blood is modeled as an incompressible non-Newtonian fluid and the flow is assumed to be steady and laminar. Hemodynamic characteristics are analyzed. Grid independence is tested on three successively refined meshes. It is observed that the abrupt expansion induced by AAA results in an immensely disturbed regime. The results may have implications not only for understanding the mechanical behavior of the blood flow inside an aneurysm artery but also for investigating the mechanical behavior of the blood flow in different arterial diseases, such as atherosclerosis.

EFFECT OF PROGRESSIVE DEGREES OF SIDE-BRANCH BIFURCATION ANGLES ON FLOW IN ARTERY USING NUMERICAL SIMULATION

2016 ◽  
Vol 16 (04) ◽  
pp. 1650043
Author(s):  
HUIRONG WANG ◽  
XIAORAN WANG ◽  
YILUN JIN ◽  
GUIYING LIU ◽  
XINYUE LI ◽  
...  
Keyword(s):  
Blood Flow ◽  
Numerical Models ◽  
Human Life ◽  
Flow Characteristics ◽  
Side Branch ◽  
Computational Framework ◽  
Abdominal Aortic ◽  
Invasive Method ◽  
Serious Disease ◽  
Major Factors

Malfunction of the cardiovascular system is a serious disease affecting human life around the world that is caused by several factors. One of the major factors is atherosclerosis that is a disease of the artery. Atherosclerosis is a serious vascular condition, which always occurs in branch vessels such as the abdominal aortic bifurcation and the carotid artery bifurcation. Wall shear stress (WSS) and wall pressure gradient (WPG) pertaining to these vessels will dramatically change when the geometry of these vessels is varied. Computational hemodynamics, as an invasive method, can be employed to understand the blood flow characteristics. In this paper, blood flow through arteries with variable side branches is presented using a computational framework. Numerical models pertaining to the different side-branch bifurcation angles are simulated to verify this. The side-branch bifurcation angle correlates positively to the maximum WSS experienced by the artery and this has an effect on atherogenesis. The low WPG regions are found to decrease with increased values of the angles, while the high WPG regions concentrate in the same region with larger values. Such hemodynamics information can be used to understand the effect of arterial geometrical variation on hemodynamics and the causes of atherosclerosis.

scholarly journals A Numerical Study on the Attitudes and Aerodynamics of Freely Falling Hexagonal Ice Plates

2015 ◽  
Vol 72 (9) ◽  
pp. 3685-3698 ◽  
Author(s):  
Kai-Yuan Cheng ◽  
Pao K. Wang ◽  
Tempei Hashino
Keyword(s):  
Degrees Of Freedom ◽  
Numerical Study ◽  
Steady Motion ◽  
Flow Characteristics ◽  
Flow Fields ◽  
The Body ◽  
Navier Stokes ◽  
Empirical Formulas ◽  
Navier Stokes Equation ◽  
Hexagonal Ice

Abstract The fall attitudes and the flow fields of falling hexagonal ice plates are studied by numerically solving the transient incompressible Navier–Stokes equation for flow past ice plates and the body dynamics equations representing the 6-degrees-of-freedom motion that determine the position and orientation of the ice plates in response to the hydrodynamic force of the flow fields. The ice plates investigated are from 1 to 10 mm in diameter, and the corresponding Reynolds number ranges from 46 to 974. The results indicate that the 1-mm plate generates a steady flow field and exhibits a steady motion, whereas the rest of the ice plates generate unsteady flow fields and exhibit unsteady motions, including horizontal translation, rotation, and axial oscillation. The horizontal translation is primarily determined by the inclination due to oscillation. The pressure distributions around the falling plates are examined and discussed in association with the oscillation. The vortex structure in the wake of the plate is examined. Empirical formulas for fall speed, oscillation frequency, and drag coefficient are given. Potential impacts of the fall attitudes and flow characteristics on the microphysics of ice plates are discussed.

scholarly journals BLOOD FLOW ANALYSIS OF POLYURETHANE HEART VALVES AT PEAK SYSTOLE

2006 ◽  
Vol 18 (01) ◽  
pp. 13-18
Author(s):  
CHEUNG-HWA HSU
Keyword(s):  
Blood Flow ◽  
Heart Valves ◽  
Stokes Equations ◽  
Flow Analysis ◽  
Anticoagulation Therapy ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Maximum Flow ◽  
Navier Stokes ◽  
Hemodynamic Characteristics

Polyurethane (PU) heart valves provide central flow at peak systole and the associated hemodynamic characteristics are superior to that of mechanical valves with almost no anticoagulation therapy for patients. Durability performances, on the other hand, are also superior to those of biological valves. This paper analyzes blood flow characteristics of the PU heart valves at fully open position with computational fluid dynamics. These data provide information for the improvement of leaflets and leaflet support geometry to minimize the scale of recirculation zone of the flow field. To simulate the hemodynamic characteristics of the blood flow, CFX-4.3 software with the finite volume method is utilized to analyze the three-dimensional Reynolds-averaged Navier-Stokes equations. By modifying the geometry of leaflets along with the supports, the scale of vortex flow and blood velocity are reduced obviously. Maximum flow velocity reduces 33% compared to that of original model at peak systole.

scholarly journals Implementation of Portable Automatic Tourniquet with High-Elasticity Biocompatible Strap

2021 ◽  
Vol 11 (10) ◽  
pp. 4653
Author(s):  
Seong-Tak Woo ◽  
Cheol-Woo Park ◽  
Ji-Hyun Sung ◽  
Cheol-Min Park
Keyword(s):  
Blood Flow ◽  
Flow Characteristics ◽  
The Body ◽  
Ultrasound Measurement ◽  
Blood Collection ◽  
Physical Damage ◽  
Body Dimensions ◽  
Support Tools ◽  
High Elasticity ◽  
Improper Use

The most common screening techniques to diagnose a patient’s illness are blood collection and intravenous procedures. To find a collection or injection site, conventional blood collection support tools, such as latex tubing and buckle-type tourniquets, are generally used to compress the patient’s blood vessels. This conventional passive method has significant problems such as latex allergy, vulnerability to site contamination and potential bloodstream infection, and physical damage due to improper use. To overcome the disadvantages of conventional blood collection support tools, an automatic tourniquet with a high-elasticity biocompatible strap was constructed. The automatic tourniquet is designed to automatically adjust the strap length using a motor to control the pressure according to the body dimensions of patients. In order to evaluate the performance of the automatic tourniquet, blood flow characteristics were analyzed using an ultrasound measurement system. The results demonstrated that the automatic tourniquet showed better performance compared with those of other blood collection support tools.

scholarly journals Мальформации как нарушение фрактальной структуры кровеносной системы организма

2020 ◽  
Vol 90 (9) ◽  
pp. 1506
Author(s):  
В. Антонов ◽  
П. Ефремов
Keyword(s):  
Heat Transfer ◽  
Blood Flow ◽  
Life Support ◽  
Vascular System ◽  
Circulatory System ◽  
Flow Simulation ◽  
Simulation Software ◽  
Heat Fluxes ◽  
The Body ◽  
Model Base

The article contains a description of mathematical models, the bases of which is the representation of the body circulatory system as a multifractal object. As examples, we consider the solution of two problems. The first issue is related to the normal state of the body’s life support system, namely, heat transfer in human skin. The model base is the equations of hydrodynamics and heat transfer. Quantitative results of calculating heat fluxes in three layers of the dermis are presented. The second issue deals with a violation of fractality due to the presence of arteriovenous malformation in the brain vascular system. The SolidWorks 2017 Flow Simulation software product serves as the basis for the implementation of a blood flow model in the presence of malformation. As a result of the simulation, data on the velocities and blood flow in the vessels were obtained for various cases of malformations.

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