Non-Newtonian models for molecular viscosity and wall shear stress in a 3D reconstructed human left coronary artery

Soulis, Johannes V.; Giannoglou, George D.; Chatzizisis, Yiannis S.; Seralidou, Kypriani V.; Parcharidis, George E.; Louridas, George

doi:10.1016/j.medengphy.2007.02.001

Cited by 104 publications

(68 citation statements)

References 26 publications

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“…The effects of nonNewtonian fluid were also more significant in the irregular shaped model. Our simulation results were similar to those of the previous works in steady flowpressure drops and WSS for non-Newtonian flow were greater than those for Newtonian flow [3,4,26,27]. Also, the effects of non-Newtonian viscosity on pressure drop and WSS were more significant in pulsatile flow.…”

Section: Discussionsupporting

confidence: 89%

Effects of surface geometry and non-newtonian viscosity on the flow field in arterial stenoses

Jeong

Rhee

2009

J Mech Sci Technol

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Hemodynamics including flow pattern, shear stress, and blood viscosity characteristics has been believed to affect the development and progression of arterial stenosis, but previous studies lack of realistic physiological considerations such as irregular surface geometry, non-Newtonian viscosity characteristics and flow pulsatility. The effects of surface irregularities and non-Newtonian viscosity on flow fields were explored in this study using the arterial stenosis models with 48% arterial occlusions under physiological flow condition. Computational flow dynamics based on the finite volume method was employed for Newtonian and non-Newtonian fluid. The wall shear stresses (WSS) in the irregular surface model were higher compared to those in the smooth surface models. Also, non-Newtonian viscosity characteristics increase the peak WSS significantly. The dimensionless pressure drop and the time averaged WSS in pulsatile flow were higher than those in steady flow. But pulsatility effects on pressure and WSS were less significant compared to non-Newtonian viscosity effects. Therefore, irregular surface geometry and non-Newtonian viscosity characteristics should be considered in predicting pressure drop and WSS in stenotic arteries.

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Section: Discussionsupporting

confidence: 89%

Effects of surface geometry and non-newtonian viscosity on the flow field in arterial stenoses

Jeong

Rhee

2009

J Mech Sci Technol

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“…The mechanism responsible for this phenomenon is the exponential increase of blood viscosity when shear rate decreases below 100 s À1 , which produces a buffer effect. 30,33 This non-Newtonian fluid behavior, characteristic of human blood, would exponentially increase resting retrograde ESS. Therefore, it is conceivable that retrograde ESS during blood flow restriction 15 and/ or handgrip exercise 16 was not significantly greater than during resting conditions.…”

Section: Discussionmentioning

confidence: 99%

Enhanced external counterpulsation creates acute blood flow patterns responsible for improved flow-mediated dilation in humans

Gurovich

Braith

2012

Hypertens Res

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Enhanced external counterpulsation (EECP) is a FDA-approved treatment for patients with coronary artery disease and unstable angina. Although beneficial effects of EECP have been linked to central/cardiac adaptations, recent findings have shown peripheral/vascular effects. Here, we sought to determine EECP-induced blood flow patterns and their association with vascular function. The present study was designed to investigate endothelium-mediated arterial vasodilation changes after one 45-min session of either EECP or Sham EECP in 18 randomly assigned apparently healthy, young men (25±4 years). Brachial (b) and femoral (f) flow-mediated dilation (FMD) were assessed before and within 10 min after completing EECP or Sham. After 20 min of EECP, peak blood flow velocity (V) and brachial and femoral artery diameters (D) were recorded live for 2 min. In addition, a blood sample was drawn from the earlobe to determine hematocrit and then to calculate blood viscosity (l) and density (q), Reynolds number (Re ¼ V*D*q/l), and endothelial shear stress (ESS ¼ 2l*V/D). EECP increased retrograde shear stress and retrograde-turbulent blood flow in the femoral artery and antegrade-laminar shear stress in the brachial artery. fFMD was increased after EECP compared with Sham and baseline (fFMD ¼ 13.1±3.7 vs. 7.9±4.6% and 7.8±4.5%, respectively, Po0.05) and bFMD was increased after EECP compared with baseline (bFMD ¼ 10.6±4.8 vs. 7.0±3.5%, Po0.05), despite different blood flow patterns. These results provide novel evidence that a single session of EECP-induced blood flow patterns improve endothelial function in peripheral muscular conduit arteries.

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“…Blood was simulated as a Newtonian fluid with a viscosity of 3.5 cp and a nonNewtonian fluid using a Casson model (g 0 = 0.001 Pa s, s y = 0.1 Á (0.625H) 3 , and H = 0.4) [6,37]. For the Casson model, the viscosity was limited to no more than three times the viscosity of the Newtonian fluid to avoid the singularity near the zero-shear rates.…”

Section: Numerical Investigationmentioning

confidence: 99%

Timing and size of flow impingement in a giant intracranial aneurysm at the internal carotid artery

Jou

Mawad

2011

Med Biol Eng Comput

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Flow impingement is regarded as a key factor for aneurysm formation and rupture. Wall shear stress (WSS) is often used to evaluate flow impingement even though WSS and impinging force are in two different directions; therefore, this raises an important question of whether using WSS for evaluation of flow impingement size is appropriate. Flow impinging behavior in a patient-specific model of a giant aneurysm (GA) at the internal carotid artery (ICA) was analyzed by computational fluid dynamics simulations. An Impingement Index (IMI) was used to evaluate the timing and size of flow impingement. In theory, the IMI is related to the WSS gradient, which is known to affect vascular biology of endothelial cells. Effect of non-Newtonian fluid, aneurysm size, and heart rate were also studied. Maximum WSS is found to be proportional to the IMI, but the area of high wall shear is not proportional to the size of impingement. A faster heart rate or larger aneurysm does not produce a larger impinging site, and the Newtonian assumption overestimates the size of impingement. Flow impingement at the dome occurs approximately 0.11 s after the peak of flow waveform is attained. This time delay also increases with aneurysm size and varies with heart rate and waveform.

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Non-Newtonian models for molecular viscosity and wall shear stress in a 3D reconstructed human left coronary artery

Cited by 104 publications

References 26 publications

Effects of surface geometry and non-newtonian viscosity on the flow field in arterial stenoses

Effects of surface geometry and non-newtonian viscosity on the flow field in arterial stenoses

Enhanced external counterpulsation creates acute blood flow patterns responsible for improved flow-mediated dilation in humans

Timing and size of flow impingement in a giant intracranial aneurysm at the internal carotid artery

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