Hydrodynamic instability and regimes of fragmentation of drops

Girin, A. G.

doi:10.1007/bf01840722

Cited by 11 publications

(11 citation statements)

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“…The flow near the liquid − gas interface depends on the media properties. The effect of the velocity profile peculiarities on the liquid − gas interface instability was studied in (Girin 1985). It was established that variations of the media inertial and viscous properties modify the profile, transforming the flow within the conjugated liquid -gas boundary layers.…”

Section: The Instability Of a Gradient Flow Near Liquid-gas Interfacementioning

confidence: 99%

“…(1). The instability investigation (Girin 1985) mentioned above resulted in the algebraic dispersion relation of the fourth power with respect to the frequency ω of the disturbance of the form E = E 0 exp(ihx − iωt). In the case of liquid − gas systems (i.e.…”

Section: The Instability Of a Gradient Flow Near Liquid-gas Interfacementioning

confidence: 99%

“…The unstable root of Eq. (1) defines a different type of periodical instability, called the gradient instability (Girin 1985;, the mechanism of which is generated within the liquid boundary layer by the huge velocity gradient, ∂V m x /∂y ≈ V s /δ m , which ranges up to (10 4 −10 5 )s −1 for liquid drops as well as for meteoroids. This will be demonstrated later with Eqs.…”

Section: The Instability Of a Gradient Flow Near Liquid-gas Interfacementioning

confidence: 99%

“…(1), it appears that the fastest wave parameters only depend on the surface Weber number, We s . The dimensionless wavenumber ∆ f = 2πδ m /λ f and growth rate factor Im(Ω f ) were calculated in (Girin 1985) and are given in Fig. 5 as functions of We s .…”

Section: The Mechanics Of Particle Releasementioning

confidence: 99%

“…The inequality We ∞ Re −0.5 ∞ 0.3 was first found empirically by Rabin et al (1960) as a condition for the stripping mode of a liquid drop breakup. For the standard air conditions, α = 1.3 × 10 −3 , it was revealed and grounded theoretically in (Girin 1985) as the criterion for the gradient instability existence at a drop surface. While Eq.…”

Section: The Mechanics Of Particle Releasementioning

confidence: 99%

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A hydrodynamic mechanism of meteor ablation

Girin

2017

A&A

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Context. Hydrodynamic conditions are similar in a molten meteoroid and a liquid drop in a high-speed airflow. Despite the fact that the latter is well-studied, both experimentally and theoretically, hydrodynamic instability theory has not been applied to study the fragmentation of molten meteoroids. Aims. We aim to treat quasi-continuous spraying of meteoroid melt due to hydrodynamic instability as a possible mechanism of ablation. Our objectives are to calculate the time development of particle release, the released particle sizes and their distribution by sizes, as well as the meteoroid mass loss law. Methods. We have applied gradient instability theory to model the behaviour of the meteoroid melt layer and its interaction with the atmosphere. We have assumed a spherical meteoroid and that the meteoroid has a shallow entry angle, such that the density of the air stream interacting with the meteoroid is nearly constant. Results. High-frequency spraying of the molten meteoroid is numerically simulated. The intermediate and final size distributions of released particles are calculated, as well as the meteoroid mass loss law. Fast and slow meteoroids of iron and stone compositions are modelled, resulting in significant differences in the size distribution of melt particles sprayed from each meteoroid. Less viscous iron melt produces finer particles and a denser aerosol wake than a stony one does. Conclusions. Analysis of the critical conditions for the gradient instability mechanism shows that the dynamic pressure of the airstream at heights up to 100 km is sufficient to overcome surface tension forces and pull out liquid particles from the meteoroid melt by means of unstable disturbances. Hence, the proposed melt-spraying model is able to explain quasi-continuous mode of meteoroid fragmentation at large heights and low dynamic pressures. A closed-form solution of the meteoroid ablation problem is obtained due to the melt-spraying model usage, at the meteoroid composition, initial radius and velocity being given.

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Section: The Instability Of a Gradient Flow Near Liquid-gas Interfacementioning

confidence: 99%

Section: The Instability Of a Gradient Flow Near Liquid-gas Interfacementioning

confidence: 99%

Section: The Instability Of a Gradient Flow Near Liquid-gas Interfacementioning

confidence: 99%

Section: The Mechanics Of Particle Releasementioning

confidence: 99%

Section: The Mechanics Of Particle Releasementioning

confidence: 99%

See 3 more Smart Citations