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Pulsatile flow

About: Pulsatile flow is a research topic. Over the lifetime, 6278 publications have been published within this topic receiving 149638 citations.


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TL;DR: In this paper, a 3D-PTV-based, non-intrusive measuring method is used to analyze the aortic flow velocities and the turbulent fluctuations.
Abstract: A three-dimensional, pulsatile flow in a realistic phantom of a human ascending aorta with compliant walls is investigated in vitro. Three-Dimensional Particle Tracking Velocimetry (3D-PTV), an image-based, non-intrusive measuring method is used to analyze the aortic flow. The flow velocities and the turbulent fluctuations are determined. The velocity profile at the inlet of the ascending aorta is relatively flat with a skewed profile toward the inner aortic wall in the early systole. In the diastolic phase, a bidirectional flow is observed with a pronounced retrograde flow developing along the inner aortic wall, whereas the antegrade flow migrates toward the outer wall of the aorta. The spatial and temporal evolution of the vorticity field shows that the vortices begin developing along the inner wall during the deceleration phase and attenuate in the diastolic phase. The change in the cross-sectional area is more distinct distal to the inlet cross section. The mean kinetic energy is maximal in the peak systole, whereas the turbulent kinetic energy increases in the deceleration phase and reaches a maximum in the beginning of the diastolic phase. Finally, in a Lagrangian analysis, the temporal evolution of particle dispersion was studied. It shows that the dispersion is higher in the deceleration phase and in the beginning of the diastole, whereas in systole, it is smaller but non-negligible.

72 citations

Journal ArticleDOI
TL;DR: Pulsatile flow through a one-sided diffuser and static divergent vocal-fold models is investigated to ascertain the relevance of viscous-driven flow asymmetries in the larynx, and conclusions are made regarding the impact of the Coanda effect on the sound source contribution in speech.
Abstract: Pulsatile flow through a one-sided diffuser and static divergent vocal-fold models is investigated to ascertain the relevance of viscous-driven flow asymmetries in the larynx. The models were 7.5 times real size, and the flow was scaled to match Reynolds and Strouhal numbers, as well as the translaryngeal pressure drop. The Reynolds number varied from 0–2000, for flow oscillation frequencies corresponding to 100 and 150Hz life-size. Of particular interest was the development of glottal flow skewing by attachment to the bounding walls, or Coanda effect, in a pulsatile flow field, and its impact on speech. The vocal folds form a divergent passage during phases of the phonation cycle when viscous effects such as flow separation are important. It was found that for divergence angles of less than 20degrees, the attachment of the flow to the vocal-fold walls occurred when the acceleration of the forcing function was zero, and the flow had reached maximum velocity. For a divergence angle of 40degrees, the fully ...

71 citations

Journal Article
TL;DR: The use of information obtained by measuring FLOW and renal resistance while kidneys are undergoing pulsatile perfusion offers quantitative data to determine suitability of an organ for transplant, which may be more accurate than the combination of demographic variables with past and current medical information that has been traditionally used to evaluate donor suitability.
Abstract: Pulsatile preservation of cadaveric kidney allografts allows effective organ preservation and the opportunity to obtain information about the quality of the organ during storage. The use of information obtained by measuring FLOW (ml/min) and renal resistance (mean perfusion pressure/FLOW (ml/min)) while kidneys are undergoing pulsatile perfusion offers quantitative data to determine suitability of an organ for transplant. This may be more accurate than the combination of demographic variables with past and current medical information that has been traditionally used to evaluate donor suitability. We have evaluated 82 kidneys that received a period of pulsatile preservation at our institution. Kidneys were from consecutive donors age > or = 42 years and were stratified into three high risk groups: donor age > or = 60 (48%), the presence of hypertension (52%), and IMPORT kidney (48%). All IMPORT kidneys were obtained through UNOS after the local center considered them unacceptable for transplant and none were 6-antigen match organs. Kidneys were discarded if they failed to have a FLOW > or = 70 ml/min or RR or = 60 (p = 0.002). The average FLOW and RR of transplanted kidneys was 103 ml/min and 0.3283 respectively. Six of 69 (8.6%) transplanted organs required dialysis (ATN). No pump parameters predicted the development of ATN although 5 of 6 kidneys were IMPORTs. Recipient outcome data, including 72-hour urine output and day 10 serum Cr, were affected by organ risk group, but these did not impact on patient care.(ABSTRACT TRUNCATED AT 250 WORDS)

71 citations

Journal ArticleDOI
TL;DR: It was concluded that local haemodynamics, practically described by velocity, pressure drop, wall shear stress (WSS) and flow rates, may be strongly influenced by the local geometry, especially at the anastomotic sites.

71 citations

Journal ArticleDOI
TL;DR: The temporal distribution of hemodynamic stresses in pulsatile flow and their physical implications in AAA rupture are discussed in Part II of this paper.
Abstract: Numerical predictions of blood flow patterns and hemodynamic stresses in Abdominal Aortic Aneurysms (AAAs) are performed in a two-aneurysm, axisymmetric, rigid wall model using the spectral element method. Homogeneous, Newtonian blood flow is simulated under steady conditions for the range of Reynolds numbers 10 < or =Re < or =2265. Flow hemodynamics are quantified by calculating the distributions of wall pressure (p(w)), wall shear stress (tau(w)), Wall Shear Stress Gradient (WSSG). A correlation between maximum values of hemodynamic stresses and Reynolds number is established, and the spatial distribution of WSSG is considered as a hemodynamic force that may cause damage to the arterial wall at an intermediate stage of AAA growth. The temporal distribution of hemodynamic stresses in pulsatile flow and their physical implications in AAA rupture are discussed in Part II of this paper.

71 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023274
2022641
2021170
2020181
2019171
2018189