An experimental study of transitional pulsatile pipe flow

Trip, Renzo; Kuik, Dirk Jan; Westerweel, J.; Poelma, Christian

doi:10.1063/1.3673611

Cited by 74 publications

(62 citation statements)

References 41 publications

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“…In pulsatile flow, these structures are usually observed during or just after the decelerating phase of the cardiac cycle [26,27]. If the flow does not (fully) relaminarize during the cardiac cycle, a continuous modulation in the intensity of turbulent flow can be observed [26]. Apart from the natural transition of the flow to turbulence (i.e.…”

Section: Transitional Flowmentioning

confidence: 99%

Transitional flow in aneurysms and the computation of haemodynamic parameters

Poelma

Watton

Ventikos

2015

J. R. Soc. Interface.

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Haemodynamic forces appear to play an influential role in the evolution of aneurysms. This has led to numerous studies, usually based on computational fluid dynamics. Their focus is predominantly on the wall shear stress (WSS) and associated derived parameters, attempting to find correlations between particular patterns of haemodynamic indices and regions subjected to disease formation and progression. The indices are generally determined by integration of flow properties over a single cardiac cycle. In this study, we illustrate that in some cases the transitional flow in aneurysms can lead to significantly different WSS distributions in consecutive cardiac cycles. Accurate determination of time-averaged haemodynamic indices may thus require simulation of a large number of cycles, which contrasts with the common approach to determine parameters using data from a single cycle. To demonstrate the role of transitional flow, two exemplary cases are considered: flow in an abdominal aortic aneurysm and in an intracranial aneurysm. The key differences that are observed between these cases are explained in terms of the integral timescale of the transitional flows in comparison with the cardiac cycle duration: for relatively small geometries, transients will decay before the next cardiac cycle. In larger geometries, transients are still present when the systolic phase produces new instabilities. These residual fluctuations serve as random initial conditions and thus seed different flow patterns in each cycle. To judge whether statistics are converged, the derived indices from at least two successive cardiac cycles should be compared.

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Section: Transitional Flowmentioning

confidence: 99%

Transitional flow in aneurysms and the computation of haemodynamic parameters

Poelma

Watton

Ventikos

2015

J. R. Soc. Interface.

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“…Some assumed the blood flow in coronary arteries to be laminar (7)(8)(9)(10)(11)(12)(13)(14) and behave as Newtonian fluid (8,(15)(16)(17) and some studied turbulence transition and non-Newtonian effects considering idealized straight arterial model with single model stenosis obstruction (11,15,(17)(18)(19)(20)(21). Several experimental investigations have been carried out on flow disturbances in the downstream region of idealized modeled stenosis (18,22,23). Ahmed and Giddens (24) examined the development of flow disturbances downstream of smooth 25%, 50% and 75% area reductions in an idealized geometry and observed a substantial increase in the disturbance level above 50% stenosis.…”

Section: Introductionmentioning

confidence: 99%

Numerical analysis of the effect of turbulence transition on the hemodynamic parameters in human coronary arteries

Mahalingam¹,

Gawandalkar²,

Kini³

et al. 2016

Cardiovasc. Diagn. Ther.

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Background: Local hemodynamics plays an important role in atherogenesis and the progression of coronary atherosclerosis disease (CAD). The primary biological effect due to blood turbulence is the change in wall shear stress (WSS) on the endothelial cell membrane, while the local oscillatory nature of the blood flow affects the physiological changes in the coronary artery. In coronary arteries, the blood flow Reynolds number ranges from few tens to several hundreds and hence it is generally assumed to be laminar while calculating the WSS calculations. However, the pulsatile blood flow through coronary arteries under stenotic condition could result in transition from laminar to turbulent flow condition.Methods: In the present work, the onset of turbulent transition during pulsatile flow through coronary arteries for varying degree of stenosis (i.e., 0%, 30%, 50% and 70%) is quantitatively analyzed by calculating the turbulent parameters distal to the stenosis. Also, the effect of turbulence transition on hemodynamic parameters such as WSS and oscillatory shear index (OSI) for varying degree of stenosis is quantified. The validated transitional shear stress transport (SST) k-ω model used in the present investigation is the best suited Reynolds averaged Navier-Stokes turbulence model to capture the turbulent transition. The arterial wall is assumed to be rigid and the dynamic curvature effect due to myocardial contraction on the blood flow has been neglected.Results: Our observations shows that for stenosis 50% and above, the WSS avg , WSS max and OSI calculated using turbulence model deviates from laminar by more than 10% and the flow disturbances seems to significantly increase only after 70% stenosis. Our model shows reliability and completely validated.Conclusions: Blood flow through stenosed coronary arteries seems to be turbulent in nature for area stenosis above 70% and the transition to turbulent flow begins from 50% stenosis.

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“…DISA 55M10 was used as the CTA bridge, the voltage signal was recorded by measuring card NI SCC-68. The method of PIV (Particle Image Velocimetry) can be also use for the identification of the point of transition to turbulence [22]. In that case, it is very important to set the PIV system parameters correctly, as well as to use a correct size of a seeding particles [23].…”

Section: Methodsmentioning

confidence: 99%

The influence of flow parameters on the transition to turbulence in pulsatile flow

Schmirler

Matěcha

Netřebská

et al. 2014

EPJ Web of Conferences

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Abstract. The paper is focused on the experimental investigation of the flow parameters influence (stationary component of flow, frequency, amplitude) on the transition to turbulence in pulsatile flow in a straight square channel. The measurements were performed in water. The wall shear stress (WSS) was measured with the help of Constant Temperature Anemometry (CTA) method using a hot-film flush mounted probe. At the same time the pressure drop was measured using the pressure sensors. The pulsatile flow was generated by superposition of the stationary and oscillatory flow components.

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An experimental study of transitional pulsatile pipe flow

Cited by 74 publications

References 41 publications

Transitional flow in aneurysms and the computation of haemodynamic parameters

Transitional flow in aneurysms and the computation of haemodynamic parameters

Numerical analysis of the effect of turbulence transition on the hemodynamic parameters in human coronary arteries

The influence of flow parameters on the transition to turbulence in pulsatile flow

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