Fragmentation and energy dissipation in collisions of polydisperse granular clusters

Umstätter, Philipp; Urbassek, Herbert M.

doi:10.1051/0004-6361/201936527

“…The collisional behavior of dust aggregates has been reported in a large number of studies based on both laboratory experiments (e.g., Blum & Wurm 2008;Güttler et al 2010;Shimaki & Arakawa 2012;Brisset et al 2016Brisset et al , 2017Schräpler et al 2018Schräpler et al , 2022Fritscher & Teiser 2021) and numerical simulations (e.g., Wada et al 2007Wada et al , 2008Wada et al , 2009Wada et al , 2013Paszun & Dominik 2009;Seizinger et al 2013;Sirono & Ueno 2017;Umstätter & Urbassek 2020, 2021aHasegawa et al 2021;Sirono & Kudo 2021). It is known that the threshold collision velocity for the fragmentation of dust aggregates, v fra , depends on material properties of constituent particles.…”

Section: Introductionmentioning

confidence: 99%

Impacts of Viscous Dissipation on Collisional Growth and Fragmentation of Dust Aggregates

Arakawa

¹

,

Tanaka

²

,

Kokubo

³

2022

ApJ

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Understanding the collisional behavior of dust aggregates consisting of submicron-sized grains is essential to unveiling how planetesimals formed in protoplanetary disks. It is known that the collisional behavior of individual dust particles strongly depends on the strength of viscous dissipation force; however, impacts of viscous dissipation on the collisional behavior of dust aggregates have not been studied in detail, especially for the cases of oblique collisions. Here we investigated the impacts of viscous dissipation on the collisional behavior of dust aggregates. We performed numerical simulations of collisions between two equal-mass dust aggregates with various collision velocities and impact parameters. We also changed the strength of viscous dissipation force systematically. We found that the threshold collision velocity for the fragmentation of dust aggregates barely depends on the strength of viscous dissipation force when we consider oblique collisions. In contrast, the size distribution of fragments changes significantly when the viscous dissipation force is considered. We obtained the empirical fitting formulae for the size distribution of fragments for the case of strong dissipation, which would be useful to study the evolution of size and spatial distributions of dust aggregates in protoplanetary disks.

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“…Even in the absence of chondrules, dust aggregates in space are not monodisperse, but obey a powerlaw distribution (Mathis et al 1977). Simulation studies have pointed out that the collisional behavior of such aggregates can be approximated by monodisperse aggregates with a suitably chosen radius (Ormel et al 2009;Umstätter & Urbassek 2020). Our present study goes beyond these comparisons by showing that the chondrule content in large aggregates affects the aggregate stability in collisions and the sizes of fragments that are created.…”

Section: Discussionmentioning

confidence: 65%

“…In simulation studies, aggregates are often assumed to consist of spherical grains of a single size (Wada et al 2008(Wada et al , 2011Ringl et al 2012a). In protoplanetary disks, grain size distributions differ significantly from such a monodisperse distribution and are expected to follow a power law (Mathis et al 1977) -see also Zubko et al (1996) -but the effects on aggregate collisions appear to be minor as long as they are compared to a monodisperse distribution with a suitably defined size (Umstätter & Urbassek 2020).…”

Section: Introductionmentioning

confidence: 99%

Granular mechanics simulations of collisions between chondritic aggregates

Umstätter

¹

,

Urbassek

²

2021

A&A

Self Cite

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Context. Collisions of dust aggregates are relevant for the evolution of protoplanetary disks. Aims. While in the past interest focused on aggregates composed of monodisperse grains, here we study the collision of chondritic aggregates, in which – besides a majority of dust grains – larger chondrules are embedded. Methods. We use granular-mechanics simulations to study collisions of chondritic aggregates. Results. Low-velocity collisions lead to pancake-shaped deformations of the fused cluster accompanied by a compaction of the dust grains. Higher collision velocities fragment the aggregates. While some chondrules are almost laid bare after the collision, we find that the largest fragments typically contain chondrules; large fragments thus capture chondrules. Grain compaction is accompanied by an increase in grain – chondrule contacts and is maximum for intermediate velocities, just before aggregates start fragmenting. Conclusions. The presence of chondrules considerably influences the fragmentation behavior of dust aggregates.

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“…The collisional behavior of dust aggregates has been reported in a large number of studies based on both laboratory experiments (e.g., Blum & Wurm 2008;Güttler et al 2010;Shimaki & Arakawa 2012;Brisset et al 2016Brisset et al , 2017Schräpler et al 2018Schräpler et al , 2022Fritscher & Teiser 2021) and numerical simulations (e.g., Wada et al 2007Wada et al , 2008Wada et al , 2009Wada et al , 2013Paszun & Dominik 2009;Seizinger et al 2013;Sirono & Ueno 2017;Umstätter & Urbassek 2020, 2021aHasegawa et al 2021;Sirono & Kudo 2021). It is known that the threshold collision velocity for the fragmentation of dust aggregates, v fra , depends on material properties of constituent particles.…”

Section: Introductionmentioning

confidence: 99%

Impacts of viscous dissipation on collisional growth and fragmentation of dust aggregates

Arakawa,

Tanaka,

Kokubo

2022

Preprint

0

View full text Add to dashboard Cite

Understanding the collisional behavior of dust aggregates consisting of submicron-sized grains is essential to unveiling how planetesimals formed in protoplanetary disks. It is known that the collisional behavior of individual dust particles strongly depends on the strength of viscous dissipation force; however, impacts of viscous dissipation on the collisional behavior of dust aggregates have not been studied in detail, especially for the cases of oblique collisions. Here we investigated the impacts of viscous dissipation on the collisional behavior of dust aggregates. We performed numerical simulations of collisions between two equal-mass dust aggregates with various collision velocities and impact parameters. We also changed the strength of viscous dissipation force systematically. We found that the threshold collision velocity for the fragmentation of dust aggregates barely depends on the strength of viscous dissipation force when we consider oblique collisions. In contrast, the size distribution of fragments changes significantly when the viscous dissipation force is considered. We obtained the empirical fitting formulae for the size distribution of fragments for the case of strong dissipation, which would be useful to study the evolution of size and spatial distributions of dust aggregates in protoplanetary disks.

show abstract

Fragmentation and energy dissipation in collisions of polydisperse granular clusters

Cited by 9 publications

References 28 publications

Impacts of Viscous Dissipation on Collisional Growth and Fragmentation of Dust Aggregates

Impacts of Viscous Dissipation on Collisional Growth and Fragmentation of Dust Aggregates

Granular mechanics simulations of collisions between chondritic aggregates

Impacts of viscous dissipation on collisional growth and fragmentation of dust aggregates

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