Biological Computer Modeling / Biological Computer Simulation
Mahdie Roghani Yazdi; Nadia Naghavi; Faride Sadat Hosseini
Volume 9, Issue 2 , July 2015, , Pages 143-161
Abstract
A tumor cannot grow more than a few millimeters without a blood supply (avascular tumor), and for further growth it must initiate angiogenesis process. A vascularized tumor, which is permeated with blood vessels, rapidly increases in mass because of the new source of oxygen. In this study, a discrete ...
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A tumor cannot grow more than a few millimeters without a blood supply (avascular tumor), and for further growth it must initiate angiogenesis process. A vascularized tumor, which is permeated with blood vessels, rapidly increases in mass because of the new source of oxygen. In this study, a discrete mathematical model of angiogenesis process with considering the penetration of blood flow through the vessels in the two-dimensional network is presented. This structure is coupled with an adaptive model of sprouts spacing along the parent blood vessel at the beginning of the angiogenesis process. Then, progression of these sprouts in the extracellular matrix and their penetration into the tumor as well as penetration of blood flow through the capillary structure is presented. This model incorporates three steps of adaptive sprout spacing along the parent blood vessel, sprout progression, and blood flow and network remodeling. Then, based on the simulated vasculature network, oxygentransmission and other vital chemicals needed for continuous tumor growth are simulated. In this model we assumed that the growth of the tumor is driven by cell division. The tumor growth and angiogenesis are coupled by the changes of micro environment including oxygen, tumor growth factor, and the extracellular matrix concentration. Also, we have tried to create space and time adaptations in parameters of the model.
Cardiovascular Biomechanics
Mehdi Molaei; Mohammad Saeid Saeidi; Bahar Firoozabadi
Volume 5, Issue 4 , June 2011, , Pages 279-288
Abstract
Study of Physiological Parameters of the Cardiovascular System by One Dimensional and Numerical Simulation. Owning to important role of the cardiovascular system in the human body and increase of cardiovascular diseases from day to day, in this study, we try to simulate a system of arteries by using ...
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Study of Physiological Parameters of the Cardiovascular System by One Dimensional and Numerical Simulation. Owning to important role of the cardiovascular system in the human body and increase of cardiovascular diseases from day to day, in this study, we try to simulate a system of arteries by using one dimensional numerical modeling. For the first time in the one dimensional simulation, we use the finite volume method for discretization of Navier-Stocks equations coupled with the state equation. In order to develop the outflow boundary condition, we use a kind of lumped model called arteriole structure tree. Results of this study are verified by results of other one dimensional modeling such as the characteristic method and are showed that finite volume method is able to demonstrate characteristic of blood flow in arteries. Normal pressure and flow profiles in main systemic arteries are determined, and it is founded that the pressure profile becomes steeper with distance from the heart, which is in agreement with physiological patterns. Furthermore, we can show that when elasticity of arteries is increased in arterioscleroses disease, systolic pressure increases, yet diastolic pressure decreases. Finally, according to available results, it is clear that the finite volume method is useful to simulate numerically and one dimensionally the cardiovascular system.
Cardiovascular Biomechanics
Ahmad Ramezani Saadatabadi; Majid Ahmadlouy Darab; Farzan Ghalichi; Ataollah Kamyabi
Volume 4, Issue 1 , June 2010, , Pages 65-72
Abstract
This study aimed to simulate three dimensional pulsatile Newtonian blood flow in End-to-Side anastomosis of Aorta-coronary bypass using ascending aorta velocity flow wave as graft inlet and left anterior descending coronary artery (LAD) velocity flow wave as coronary inlet for 50% symmetric stenosis. ...
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This study aimed to simulate three dimensional pulsatile Newtonian blood flow in End-to-Side anastomosis of Aorta-coronary bypass using ascending aorta velocity flow wave as graft inlet and left anterior descending coronary artery (LAD) velocity flow wave as coronary inlet for 50% symmetric stenosis. We have supposed that LAD walls were rigid and had no spatial mobility due to heart beats. In order to investigate the graft angles effects on blood flow, especially on the wall shear stress magnitudes, 20, 30 and 40 degrees graft angles were used. Using ascending aorta and LAD pulses simultaneously as boundary conditions for the first time is one of the important features of this study because already these boundary conditions have not been used simultaneously. We considered prograde flow effects. Appearance of recirculation flows in various degrees of grafting angles, existence of secondary flows and increased in their effects specially in pulses deceleration phase, existence of double core helical flows and increase in their intensify specially at the systole peak and the rise in the spatial wall shear stress gradient by increasing in the graft angle are some of important results of this study. Finally, according to our assumptions we suggest 20 to 30 degrees as desired angles for grafting.
Fluid-Structure Interaction in Biological Media / FSI
Afsane Mojra; Mohammad Tafazzoli Shadpour; Ehsan Yakhshi Tafti
Volume 2, Issue 1 , June 2008, , Pages 9-20
Abstract
Arterial stenosis and the consequent cardiovascular diseases such as atherosclerosis remain the major cause of mortality in the world. In this study, blood flow was analyzed in a three-dimensional model of stenosed carotid artery with asymmetric stenosis utilizing fluid-structure interaction method. ...
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Arterial stenosis and the consequent cardiovascular diseases such as atherosclerosis remain the major cause of mortality in the world. In this study, blood flow was analyzed in a three-dimensional model of stenosed carotid artery with asymmetric stenosis utilizing fluid-structure interaction method. The modeling was performed by ANSYS finite element software. To overcome the software inconsistency in FSI mode, a new code was designed in ANSYS multi-physics environment for coupling of solid and fluid domains via incremental boundary iteration method. The results indicated a considerable variation of local blood pressure, velocity and shear stress in stenosed artery, high pressure drop along stenosis, compressive stress and larger flow separation zone in the post-stenotic region as the result of increased eccentricity of stenosis. The results might be applied in evaluation of plaque severity, progression of disease, plaque growth and vulnerable regions of plaque to fracture.
Fluid-Structure Interaction in Biological Media / FSI
Farzan Ghalichi; Majid Ahmadlouy Darab; Ahmad Ramezani Saadatabadi
Volume 1, Issue 2 , June 2007, , Pages 111-117
Abstract
In order to compare the aorta-coronary and coronary-coronary bypasses blood flow fields in the Endto-Side Anastomosis, we carried out numerical simulation of three dimensional pulsatile blood flow for 50% stenosis by using FLUENT 5.2.3 software. In this study, the blood was assumed to be as the Newtonian, ...
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In order to compare the aorta-coronary and coronary-coronary bypasses blood flow fields in the Endto-Side Anastomosis, we carried out numerical simulation of three dimensional pulsatile blood flow for 50% stenosis by using FLUENT 5.2.3 software. In this study, the blood was assumed to be as the Newtonian, incompressible and homogeneous fluid. The arterial wall was also considered to be rigid. Non-existence of the secondary flows in the coronary-coronary bypass blood flow fields for various degrees of bypass grafting angles against the aorta-coronary-coronary bypass, return of total blood flow toward upstream in the coronary-coronary bypass three times over a heart cycle, high temporary oscillation in the wall shear stress magnitudes for the aorta-coronary bypass and low wall shear stress magnitudes for the coronary-coronary bypass were of the important results.
