Topic
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, the flow parameters: pulsatility, elasticity and non-Newtonian viscoelasticity were considered in detail in a 90 degrees-T-bifurcation of a rigid and elastic model.
68 citations
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68 citations
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TL;DR: In the laboratory, a depulsation model is designed that uses a passive, electronically controlled, pulse-shaping device installed in series with the aorta, energized by the heart, rather than by an extracorporeal pump, and allows the autoregulatory mechanisms to retain their integrity.
Abstract: IT is now generally accepted that blood flow is unaffected by depulsation, 1-4 but there is considerable evidence that tissue function is impaired by nonpulsatile perfusion. 5-7 Although there have been many interesting studies of the effects of depulsation on renal function, their results have been contradictory. Further, because extracorporeal pumping mechanisms have been used to achieve nonpulsatile flow and because of the possible limitations imposed by the preparations used, their applicability to the intact organism is uncertain. In our laboratory, we have designed a depulsation model that uses a passive, electronically controlled, pulse-shaping device installed in series with the aorta. The device is energized by the heart, rather than by an extracorporeal pump, and allows the autoregulatory mechanisms to retain their integrity. In studies 4 of the systemic-physiologic effects of total and regional depulsation, we found a significant rise of 9.6% in mean aortic pressure and peripheral resistance when the
68 citations
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TL;DR: In this article, the authors investigated how the critical Reynolds number is affected by different pulsatile conditions, expressed as the Womersley number and the oscillatory Reynolds number, in a straight, rigid pipe using particle image velocimetry.
Abstract: The transitional regime of a sinusoidal pulsatile flow in a straight, rigid pipe is investigated using particle image velocimetry. The main aim is to investigate how the critical Reynolds number is affected by different pulsatile conditions, expressed as the Womersley number and the oscillatory Reynolds number. The transition occurs in the region of Re?=?2250-3000 and is characterized by an increasing number of isolated turbulence structures. Based on velocity fields and flow visualizations, these structures can be identified as puffs, similar to those observed in steady flow transition. Measurements at different Womersley numbers yield similar transition behavior, indicating that pulsatile effects do not play a role in the regime that is investigated. Variations of the oscillatory Reynolds number also appear to have little effect, so that the transition here seems to be determined only by the mean Reynolds number. For larger mean Reynolds numbers, a second regime is observed: here, the flow remains turbulent throughout the cycle. The turbulence intensity varies during the cycle, but has a phase shift with respect to the mean flow component. This is caused by a growth of kinetic energy during the decelerating part and a decay during the accelerating part of the cycle. Flow visualization experiments reveal that the flow develops localized turbulence at several random axial positions. The structures quickly grow to fill the entire pipe in the decelerating phase and (partially) decay during the accelerating phase.
68 citations
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TL;DR: A 33‐year‐old patient presented with an incapacitating pulsatile tinnitus of 6 months' duration in the left ear and the radiological workup evidenced an aneurysm of the left sigmoid sinus.
Abstract: We report a newly evidenced cause of venous pulsatile tinnitus--the aneurysm of a dural sigmoid sinus. A 33-year-old patient presented with an incapacitating pulsatile tinnitus of 6 months' duration in the left ear. The radiological workup evidenced an aneurysm of the left sigmoid sinus. Selective endovascular coil occlusion of the aneurysm was followed by complete resolution of the tinnitus.
68 citations