Optimal Vortex Formation as a Unifying Principle in Biological Propulsion

Dabiri, John O.

doi:10.1146/annurev.fluid.010908.165232

Cited by 273 publications

(200 citation statements)

References 61 publications

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“…16,17,34 The concept of vortex formation time (VFT) appeared as a potentially relevant indicator in the assessment of LV functionality, being related to the dynamical properties of the intraventricular flow and valvular motion. 45,48,49 Subsequent studies on VFT evidenced its alteration in patients with diastolic dysfunction as well in those with dyskinetic regions.…”

Section: First Studies On Vortex Formationmentioning

confidence: 99%

Left Ventricular Fluid Mechanics: The Long Way from Theoretical Models to Clinical Applications

Pedrizzetti

Domenichini

2014

Ann Biomed Eng

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Abstract-The flow inside the left ventricle is characterized by the formation of vortices that smoothly accompany blood from the mitral inlet to the aortic outlet. Computational fluid dynamics permitted to shed some light on the fundamental processes involved with vortex motion. More recently, patient-specific numerical simulations are becoming an increasingly feasible tool that can be integrated with the developing imaging technologies. The existing computational methods are reviewed in the perspective of their potential role as a novel aid for advanced clinical analysis. The current results obtained by simulation methods either alone or in combination with medical imaging are summarized. Open problems are highlighted and perspective clinical applications are discussed.

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Section: First Studies On Vortex Formationmentioning

confidence: 99%

Left Ventricular Fluid Mechanics: The Long Way from Theoretical Models to Clinical Applications

Pedrizzetti

Domenichini

2014

Ann Biomed Eng

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“…13,14 This has been the subject of recent and ongoing research because a formation time of T Ϸ 4 has been observed in many vortex generating devices. 13 For example, such a vortex formation time was first observed in piston-cylinder vortex ring generators, 14 but the same T Ϸ 4 was also observed in flow over a cylinder 15 and over flapping wings. 16 Under the current setup, the vortex formation time is defined as…”

Section: -9mentioning

confidence: 99%

The leading-edge vortex and quasisteady vortex shedding on an accelerating plate

2010

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A computational inquiry focuses on leading-edge vortex ͑LEV͒ growth and shedding during acceleration of a two-dimensional flat plate at a fixed 10°-60°angle of attack and low Reynolds number. The plate accelerates from rest with a velocity given by a power of time ranging from 0 to 5. During the initial LEV growth, subtraction of the added mass lift from the computed lift reveals an LEV-induced lift augmentation evident across all powers and angles of attack. For the range of Reynolds numbers considered, a universal time scale exists for the peak when ␣ Ն 30°, with augmentation lasting about four to five chord lengths of translation. This time scale matches well with the half-stroke of a flying insect. An oscillating pattern of leading-and trailing-edge vortex shedding follows the shedding of the initial LEV. The nondimensional frequency of shedding and lift coefficient minima and maxima closely match their values in the absence of acceleration. These observations support a quasisteady theory of vortex shedding, where dynamics are determined primarily by velocity and not acceleration. Finally, the nondimensional vortex formation time is found to be a function of the Reynolds number, but only weakly when the Reynolds number is high.

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“…Earlier studies have described vortex formation in terms of one-directional transmitral flow profiles 7,14 and the movement and rotation of the vortex ring core 13,19 . In a recent review, Dabiri suggested that the volume of the vortex ring is an important property of vortex ring formation, since a large vortex ring can transport a large amount of blood into the LV during diastole efficiently and without forming a turbulent jet 2 . Additionally, the vortex ring may enhance recoil of the atrioventricular plane towards the base of the heart during rapid filling 17 .…”

Section: Introductionmentioning

confidence: 99%

Vortex Ring Formation in the Left Ventricle of the Heart: Analysis by 4D Flow MRI and Lagrangian Coherent Structures

et al. 2012

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Recent studies suggest that vortex ring formation during left ventricular (LV) rapid filling is an optimized mechanism for blood transport, and that the volume of the vortex ring is an important measure. However, due to lack of quantitative methods, the volume of the vortex ring has not previously been studied. Lagrangian Coherent Structures (LCS) is a new flow analysis method, which enables in vivo quantification of vortex ring volume. Therefore, we aimed to investigate if vortex ring volume in the human LV can be reliably quantified using LCS and magnetic resonance velocity mapping (4D PC-MR). Flow velocities were measured using 4D PC-MR in nine healthy volunteers and four patients with dilated ischemic cardiomyopathy. LV LCS were computed from flow velocities and manually delineated in all subjects. Vortex volume in the healthy volunteers was 51 ± 6% of the left ventricular volume, and 21 ± 5% in the patients. Interobserver variability was -1 ± 13% and interstudy variability was -2 ± 12%. Compared to idealized flow experiments, the vortex rings showed additional complexity and asymmetry, related to endocardial trabeculation and papillary muscles. In conclusion, LCS and 4D PC-MR enables measurement of vortex ring volume during rapid filling of the LV.

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Optimal Vortex Formation as a Unifying Principle in Biological Propulsion

Cited by 273 publications

References 61 publications

Left Ventricular Fluid Mechanics: The Long Way from Theoretical Models to Clinical Applications

Left Ventricular Fluid Mechanics: The Long Way from Theoretical Models to Clinical Applications

The leading-edge vortex and quasisteady vortex shedding on an accelerating plate

Vortex Ring Formation in the Left Ventricle of the Heart: Analysis by 4D Flow MRI and Lagrangian Coherent Structures

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