Extrema of the kinetic energy and its dissipation rate in vortex flows

Chefranov, Artem S.; Chefranov, S. G.

doi:10.1134/1.1639440

Cited by 12 publications

(11 citation statements)

References 3 publications

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“…Such flows can be observed in both intense tornado-like atmospheric vortices [1][2][3] and components of the cardiovascular system [4][5][6]. In [1], in particular, it was shown that for swirled, uniformly helical vortex flow regimes it is possible to generalize the Helmholtz-Rayleigh theorem concerning a kinetic energy dissipation minimum, which corresponds to an energetically optimal mode of realization of the corresponding fluid flows in natural and artificial transport systems.…”

mentioning

confidence: 97%

On Self-Oscillations during the Outflow of a Swirled Jet

Blazhko¹,

Chefranov²

2005

Fluid Dyn

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It is shown that the core of a swirled helical flow can be described using a novel exact nonstationary solution of the hydrodynamic equations for a viscous incompressible fluid, which generalizes the rigid-body asymptotics for the Burgers and Sullivan vortices in the form of rigid-body rotation with a finite helicity. An estimate of the pressure fluctuations corresponding to this nonstationary vortex regime, which is proportional to the frequency of the swirled-jet core rotation as a rigid body and also depends on the parameters of the initial velocity field structure, is obtained. It is noted that this frequency may correspond to the frequency observed in the pressure fluctuation spectrum, which is almost proportional to the swirled flow rate in vortex acoustic emitters.

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confidence: 97%

On Self-Oscillations during the Outflow of a Swirled Jet

Blazhko¹,

Chefranov²

2005

Fluid Dyn

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“…It follows from the instability conditions obtained above that the realization of instability significantly depends on the value of the Dyakov parameter (6), which characterizes the compressibility of the medium on the shock adiabat. In this case, according to (17) and (21), the value of the exponential instability index is large precisely at relatively small modulo values of this parameter. Let us consider the representations for the Dyakov parameter and determine the physical meaning of the conditions under which such values are possible.…”

Section: Discussion and Comparison With Known Datamentioning

confidence: 84%

Dissipative instability of converging cylindrical shock wave

Chefranov

2020

Physics of Fluids

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The conditions of linear instability for a converging cylindrical shock wave in an arbitrary inviscid medium are obtained. The initial continuous cylindrical symmetry of the shock wave front is exchanged on a discrete symmetry which is determined by the most unstable small azimuthal dimensionless wave numbers 1 0    th k k of corrugation perturbations. Due to the long azimuthal wavelengths (R -the radius of the shock wave) of perturbations the shape of the resulting shock wave front is not change significantly, but the corresponding restriction of the internal energy cumulation can be caused by intensification of the rotation of the medium behind the front. The correspondence of present theory to the experimental and simulation data on underwater electrical explosion is considered.

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“…In [1] it was obtained the next generalizations of well known hydrodynamic Kelvin's theorem on flow kinetic energy T minimum and Helmholtz's theorem on minimum of the kinetic energy dissipation rate (see below ) .…”

Section: Extremes Of Kinetic Energy and Rate Of Its Dissipation In Hymentioning

confidence: 99%

Hydro-mechanical foundation for blood swirling vortex flows formation in the cardio-vascular system and the problem of artificial heart creation

Chefranov¹,

Chefranov

Chefranov³

2013

Cardiometry

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Leonardo da Vinci perhaps was the first who paid attention to the energetic efficiency of existence of vortices emerging near sines of Valsalva and defining normal functioning (opening) of aortal valve. However up to now a fundamental problem of defining of mechanisms of mysterious energetic efficiency of functioning of cardio-vascular system (CVS) of blood feeding of the organism is still remaining significantly not solved and this is, for example, one of the main restriction for the creation of artificial heart and corresponding valve systems. In the present paper, results witnessing possible important role of the very hydro-mechanical mechanism in the realization of the noted energetic efficiency of CVS due to formation in the CVS of spiral structural organization of the arterial blood flow observed by methods of MRT and color Doppler-measuring in the left ventricular of the heart and in aorta (A.Yu.Gorodkov,et.al.).

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Extrema of the kinetic energy and its dissipation rate in vortex flows

Cited by 12 publications

References 3 publications

On Self-Oscillations during the Outflow of a Swirled Jet

On Self-Oscillations during the Outflow of a Swirled Jet

Dissipative instability of converging cylindrical shock wave

Hydro-mechanical foundation for blood swirling vortex flows formation in the cardio-vascular system and the problem of artificial heart creation

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