A study of wall shear stress in 12 aneurysms with respect to different viscosity models and flow conditions

Evju, Øyvind; Valen‐Sendstad, Kristian; Mardal, Kent‐André

doi:10.1016/j.jbiomech.2013.09.004

Cited by 70 publications

(53 citation statements)

References 34 publications

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“…If a different outlet condition is imposed to build the curves, like a pulsatile pressure waveform, the most important change would be the flow rates at each daughter branch after a main bifurcation. This has been reported by Evju et al (2013), where these two outlet pressure conditions were evaluated and compared. Aneurysms located further downstream a bifurcation will be greatly affected by the new arterial flow rates because flow variation would be more evident, while cases at the bifurcation will not have important changes on the mean WSS (Evju et al, 2013).…”

Section: Usability Of the Curvesmentioning

confidence: 80%

Unraveling the relationship between arterial flow and intra-aneurysmal hemodynamics

Morales

Bonnefous

2015

Journal of Biomechanics

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Section: Usability Of the Curvesmentioning

confidence: 80%

Unraveling the relationship between arterial flow and intra-aneurysmal hemodynamics

Morales

Bonnefous

2015

Journal of Biomechanics

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“…For the present study, the assumption of blood as a Newtonian fluid was considered appropriate since previous research has indicated that the aneurysm morphology has a much more pronounced influence on the flow regime than the non-Newtonian behavior of underlying flow 13 , and the choice of Newtonian description of blood has been demonstrated to be somewhat reasonable under the assumption of laminar flow 11 . Computational models have shown very little effect of the wall deformation on the main flow patterns 55 .…”

Section: Assumptions Limitations and The Continuum Hypothesismentioning

confidence: 99%

Transitional flow in intracranial aneurysms – A space and time refinement study below the Kolmogorov scales using Lattice Boltzmann Method

2016

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Most Computational Fluid Dynamics (CFD) studies of hemodynamics in intracranial aneurysms are based on the assumption of laminar flow due to a relatively low (below 500) parent artery Reynolds number. A few studies have recently demonstrated the occurrence of transitional flow in aneurysms, but these studies employed special finite element schemes tailored to capture transitional nature of flow. In this study we investigate the occurrence of transition using a standard Lattice Boltzmann method (LBM). The LBM is used because of its computational efficiency, which in the present study allowed us to perform simulations at a higher resolution than has been done in the context of aneurysms before. The high space-time resolutions of 8 µm and 0.11 µs resulted in nearly 1 × 10 9 cells and 9 × 10 6 time steps per second and allowed us to quantify the turbulent kinetic energy at resolutions below the Kolmogorov scales. We perform an in-depth space and time refinement study on 2 aneurysms; one was previously reported laminar, while the other was reported transitional. Furthermore, we investigate the critical Reynolds number at which the flow transitions in aneurysms under time constant inflow conditions.

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“…[30]. For blood flow in larger arteries and aneurysms, Newtonian models typically capture the main flow quite accurately, for example maximal WSS, average WSS and area of low WSS correlate strongly (>0.95) between Newtonian and commonly used non-Newtonian models [9], but may overestimate WSS in areas of low shear [47].…”

Section: Modelling Of Blood Flowmentioning

confidence: 99%

“…While this assumption is often adequate [9], its effect on the transition of flow has not been studied. To address this, we employ a Modified Cross viscosity presented in Fig.…”

Section: An Illustrating Example: Transition In a Cerebral Aneurysmmentioning

confidence: 99%

On the Assumption of Laminar Flow in Physiological Flows: Cerebral Aneurysms as an Illustrative Example

Evju

Mardal

2015

MS&A

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In physiological fluid flows, except for in the heart and the aorta, the Reynolds numbers are moderate (below 1000). This is far below the typical point of transition in pipe flow, which occurs around Reynolds number 2300. Because of this, laminar flow is commonly assumed in the modelling of these flows, resulting in computational methods tailored for this flow regime. This chapter presents a critical review of this assumption, and both clinical and numerical evidence of transitional physiological flows are presented. The pulsatility and complex geometries in physiological flow are highlighted as the main reasons for a lower transition point in physiological flows. Furthermore, we discuss the threshold of transition in a particular case of an aneurysm with respect to resolution, Reynolds number and non-Newtonian viscosity modelling.

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A study of wall shear stress in 12 aneurysms with respect to different viscosity models and flow conditions

Cited by 70 publications

References 34 publications

Unraveling the relationship between arterial flow and intra-aneurysmal hemodynamics

Unraveling the relationship between arterial flow and intra-aneurysmal hemodynamics

Transitional flow in intracranial aneurysms – A space and time refinement study below the Kolmogorov scales using Lattice Boltzmann Method

On the Assumption of Laminar Flow in Physiological Flows: Cerebral Aneurysms as an Illustrative Example

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