Generation of fine aerosol as a dispersion of unstable fusion film of ablating meteoroid

Girin, A. G.; Kopyt, N.Kh.

doi:10.1016/0021-8502(94)90131-7

Cited by 2 publications

(5 citation statements)

References 2 publications

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“…In this case, droplets that result from disruption of the molten layer have a size corresponding to a thickness of the layer itself. The results obtained in Girin & Kopyt (1994) are thus valid for the case of dominant ablation.…”

Section: Introductionsupporting

confidence: 54%

“…However, the molten remnant can be fragmented afterwards by the mechanism of the Rayleigh − Taylor instability, since the current Weber number value is sufficiently large at that moment, We ∞ ≈ 100, to provide the "claviform" or "multibag" mode of the remnant breakup (Reinecke & Waldman 1975;Zhao et al 2010;Girin 2012Girin , 2014a. Some ending meteor flashes can be explained thus as the delayed bursting of their remnants (Girin 1992;Girin & Kopyt 1994), since the low-Weber modes of breakup consist in a sudden rupture of a vast thin "bag" film into the tiny droplets.…”

Section: Resultsmentioning

confidence: 99%

“…The instability of a thin molten film of a meteoroid was examined in (Girin 1992;Girin & Kopyt 1994) as a mechanism of melt spraying, so that the estimations for the droplet sizes and frequency of their release were obtained. Though, such important characteristics of the meteor phenomenon as transient distributions of the released droplets by sizes, the meteoroid ablation and deceleration laws were not found.…”

Section: Introductionmentioning

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: Introductionsupporting

confidence: 54%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A hydrodynamic mechanism of meteor ablation

Girin

2017

A&A

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“…The removal of droplets from a surface melt layer by ablation arises because of hydrodynamical instabilities caused by the flow of gas across the melt surface and is dependent on the rheological properties of the melt, the gas flow regime, the melt layer depth, and the orientation of the layer to the oncoming gas flow (Girin and Kopyt, 1998). Without gas flow across the surface of the melt layer, hydrodynamical instabilities cannot develop and no droplets can separate.…”

Section: Droplet Separation By Ablationmentioning

confidence: 99%

“…The size of ablation chondrules separated from a melt layer would have depended on the dimensions of the hydrodynamic instabilities that led to droplet separation (Girin and Kopyt, 1998). Because the maximum amplitude of an instability is the depth of the melt layer, it is reasonable to assume that large planetesimals, which could have developed the deepest melt layers, produced the largest droplets.…”

Section: Physical Properties Of Ablation Chondrulesmentioning

confidence: 99%

Chondrule formation by the ablation of small planetesimals

Genge

2000

Meteorit & Planetary Scien

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Abstract-Numerous models have been proposed to explain the formation of chondrules, but none can be reconciled with the highly diverse properties of these objects. Here the formation of chondrules by the surface melting and ablation of small planetesimals in nebula shock waves is investigated using a numerical model. It is shown that bodies between -1 mm and 500 m in diameter would have produced molten droplets by ablation during gas drag in nebula shocks stronger than -2.0 Mach. The properties of chondrules produced by ablation are estimated by comparison with meteorite fusion crusts and through consideration of the environment within the bow shock envelope of ablating planetesimals. It is suggested that most ablation chondrules will have broadly chondritic compositions with depletions in siderophile and chalcophile elements and relatively high volatile contents and textures that are mainly porphyritic. The formation of chondrules by ablation of planetesimals in shock waves was probably most important at a late stage in nebula history and occurred at the same time as chondrules formed by the melting of dust particles. The high abundance of dust particles relative to larger bodies at all stages of accretion implies that only a proportion of chondrules may have been formed by ablation and that genetic groups of chondrules with very different origins may coexist in meteorites.

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Generation of fine aerosol as a dispersion of unstable fusion film of ablating meteoroid

Cited by 2 publications

References 2 publications

A hydrodynamic mechanism of meteor ablation

A hydrodynamic mechanism of meteor ablation

Chondrule formation by the ablation of small planetesimals

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