A novel periodic boundary condition for computational hemodynamics studies

Bahramian, Fereshteh; Mohammadi, Hadi

doi:10.1177/0954411914542170

Cited by 4 publications

(2 citation statements)

References 16 publications

(27 reference statements)

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“…It should be noted that in normal physiological conditions, a fully developed turbulent profile does not form in vivo. This study examines both pressure- and velocity-based BCs at the inlet and outlet, 19,20 to create the most realistic flow regime around the valve leaflets. The flow around the bileaflet MHV (SJM model) is pulsatile and encompasses the three regimes of laminar, transient, and turbulent.…”

Section: Introductionmentioning

confidence: 99%

A novel computational model for the hemodynamics of bileaflet mechanical valves in the opening phase

Jahandardoost

Fradet

Mohammadi

2015

Proc Inst Mech Eng H

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A powerful alternative means to study the hemodynamics of bileaflet mechanical heart valves is the computational fluid dynamics method. It is well recognized that computational fluid dynamics allows reliable physiological blood flow simulation and measurements of flow parameters. To date, in almost all of the modeling studies on the hemodynamics of bileaflet mechanical heart valves, a velocity (mass flow)-based boundary condition and an axisymmetric geometry for the aortic root have been assigned, which, to some extent, are erroneous. Also, there have been contradictory reports of the profile of velocity in downstream of leaflets, that is, in some studies, it is suggested that the maximum blood velocity occurs in the lateral orifice, and in some other studies, it is postulated that the maximum velocities in the main and lateral orifices are identical. The reported values for the peak velocities range from 1 to 3 m/s, which highly depend on the model assumptions. The objective of this study is to demonstrate the importance of the exact anatomical model of the aortic root and the realistic boundary conditions in the hemodynamics of the bileaflet mechanical heart valves. The model considered in this study is based on the St Jude Medical valve in a novel modeling platform. Through a more realistic geometrical model for the aortic root and the St Jude Medical valve, we have developed a new set of boundary conditions in order to be used for the assessment of the hemodynamics of aortic bileaflet mechanical heart valves. The results of this study are significant for the design improvement of conventional bileaflet mechanical heart valves and for the design of the next generation of prosthetic valves.

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Section: Introductionmentioning

confidence: 99%

A novel computational model for the hemodynamics of bileaflet mechanical valves in the opening phase

Jahandardoost

Fradet

Mohammadi

2015

Proc Inst Mech Eng H

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“…Blood is assumed incompressible and Newtonian with dynamic viscosity of 0.0035 Pa s and density of 1060 kg/m 3 . 12,13 The last term in equation (2) ( ρ u ′ i u ′ j true¯ ) represents the Reynolds stress tensor with six new unknowns. This model is known as Reynolds-averaged Navier–Stokes (RANS).…”

Section: Methodsmentioning

confidence: 99%

Effect of heart rate on the hemodynamics of bileaflet mechanical heart valves’ prostheses (St. Jude Medical) in the aortic position and in the opening phase: A computational study

Jahandardoost

Fradet

Mohammadi

2016

Proc Inst Mech Eng H

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To date, to the best of the authors' knowledge, in almost all of the studies performed around the hemodynamics of bileaflet mechanical heart valves, a heart rate of 70-72 beats/min has been considered. In fact, the heart rate of ~72 beats/min does not represent the entire normal physiological conditions under which the aortic or prosthetic valves function. The heart rates of 120 or 50 beats/min may lead to hemodynamic complications, such as plaque formation and/or thromboembolism in patients. In this study, the hemodynamic performance of the bileaflet mechanical heart valves in a wide range of normal and physiological heart rates, that is, 60-150 beats/min, was studied in the opening phase. The model considered in this study was a St. Jude Medical bileaflet mechanical heart valve with the inner diameter of 27 mm in the aortic position. The hemodynamics of the native valve and the St. Jude Medical valve were studied in a variety of heart rates in the opening phase and the results were carefully compared. The results indicate that peak values of the velocity profile downstream of the valve increase as heart rate increases, as well as the location of the maximum velocity changes with heart rate in the St. Jude Medical valve model. Also, the maximum values of shear stress and wall shear stresses downstream of the valve are proportional to heart rate in both models. Interestingly, the maximum shear stress and wall shear stress values in both models are in the same range when heart rate is <90 beats/min; however, these values significantly increase in the St. Jude Medical valve model when heart rate is >90 beats/min (up to ~40% growth compared to that of the native valve). The findings of this study may be of importance in the hemodynamic performance of bileaflet mechanical heart valves. They may also play an important role in design improvement of conventional prosthetic heart valves and the design of the next generation of prosthetic valves, such as percutaneous valves.

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Effects of Porosity in a Seepage Model on Hemodynamics

Liu

Gao

2017

J. Mech. Med. Biol.

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In this paper, we numerically investigate the effects of porosity on hemodynamics using a seepage outlet boundary condition. The results with the porosities [Formula: see text] and [Formula: see text] are compared. The comparison of the results shows that there are identical pressure, velocity and wall shear stress distributions in the artery zone; however, the velocities and wall shear stresses in the microcirculation zone with [Formula: see text] are almost as twice as those with [Formula: see text]. This work suggests that the porosity changes do not provoke variations in the artery zone, but they lead to the differences of the velocities and wall shear stresses in the microcirculation zone. The results may be the explanation of syndrome X.

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A novel periodic boundary condition for computational hemodynamics studies

Cited by 4 publications

References 16 publications

A novel computational model for the hemodynamics of bileaflet mechanical valves in the opening phase

A novel computational model for the hemodynamics of bileaflet mechanical valves in the opening phase

Effect of heart rate on the hemodynamics of bileaflet mechanical heart valves’ prostheses (St. Jude Medical) in the aortic position and in the opening phase: A computational study

Effects of Porosity in a Seepage Model on Hemodynamics

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