Collisions between ice-covered silica grains: An atomistic study

Nietiadi, Maureen L.; Rosandi, Yudi; Urbassek, Herbert M.

doi:10.1016/j.icarus.2020.113996

Cited by 14 publications

(19 citation statements)

References 53 publications

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“…The factor of 1/2 enters since velocities in our study correspond to single-particle velocities, while the JKR formula is usually used for relative velocities. (Our previous papers [19][20][21][22]35,50,51 contain an erroneous factor of 2 in the the bouncing velocity, since the velocity in the simulation referred to the single-particle velocity, while the analysis used relative velocities. Thus the bouncing velocities are higher by a factor of 2 than reported in the papers.)…”

Section: Normal and Tangential Restitution Coefficientsmentioning

confidence: 99%

“…In the lowest size regime, molecular dynamics (MD) simulation has shown as a promising venue to deliver information on collisions of NPs with sizes of a few ten nm. Here, NPs of a variety of materials have been studied, among them silica 19 , water ice 20 , and also core-shell structures 21,22 . Interesting results that have been achieved include the dependence of the bouncing velocity -that is the velocity discriminating the low-velocity sticking from the high-velocity bouncing outcomes of a collision -on material characteristics and NP size.…”

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confidence: 99%

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Bouncing and spinning of amorphous Lennard-Jones nanoparticles under oblique collisions

Nietiadi

Urbassek

2022

Sci Rep

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Collisions of Lennard-Jones nanoparticles (NPs) may be used to study the generic collision behavior of NPs. We study the collision dynamics of amorphous NPs for oblique collisions using molecular dynamics simulation as a function of collision velocity and impact parameter. In order to allow for NP bouncing, the attraction between atoms originating from differing NPs is reduced. For near-central collisions, a finite region of velocities – a ‘bouncing window’ – exists where the 2 NPs bounce from each other. At smaller velocities, energy dissipation and – at larger velocities – also NP deformation do not allow the NPs to surpass the attractive forces such that they stick to each other. Oblique collisions of non-rotating NPs convert angular momentum into NP spin. For low velocities, the NP spin is well described by assuming the NPs to come momentarily to a complete stop at the contact point (‘grip’), such that orbital and spin angular momentum share the pre-collision angular momentum in a ratio of 5:2. The normal coefficient of restitution increases with impact parameter for small velocities, but changes sign for larger velocities where the 2 NPs do not repel but their motion direction persists. The tangential coefficient of restitution is fixed in the ‘grip’ regime to a value of 5/7, but increases towards 1 for high-velocity collisions at not too small impact parameters, where the 2 NPs slide along each other.

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Section: Normal and Tangential Restitution Coefficientsmentioning

confidence: 99%

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confidence: 99%

Bouncing and spinning of amorphous Lennard-Jones nanoparticles under oblique collisions

Nietiadi

Urbassek

2022

Sci Rep

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“…The stickiness of dust particles has also been investigated in a huge number of studies (e.g., Poppe et al 2000;Güttler et al 2012;Tanaka et al 2012;Krijt et al 2013;Gundlach & Blum 2015;Nietiadi et al 2017Nietiadi et al , 2020Nietiadi et al , 2022Quadery et al 2017;Arakawa & Krijt 2021;Tsukanov & Brilliantov 2022). These studies found that the threshold velocity for the sticking in a head-on collision of individual dust particles is several times higher than that predicted for perfectly elastic spheres.…”

Section: Introductionmentioning

confidence: 99%

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

Arakawa

Tanaka

Kokubo

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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“…We acknowledge that plastic deformation, melting, and fragmentation of constituent particles are not considered in this study. These effects might be important for high-speed collisions as shown in molecular dynamics simulations (e.g., Nietiadi et al 2020Nietiadi et al , 2022. The angular velocity dependence of the strength of tangential frictions is also ignored in our simulations.…”

Section: Discussionmentioning

confidence: 98%

Collisional Growth Efficiency of Dust Aggregates and Its Independence of the Strength of Interparticle Rolling Friction

Arakawa

Tanaka

Kokubo

2022

ApJ

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The pairwise collisional growth of dust aggregates consisting of submicron-sized grains is the first step of planet formation, and understanding the collisional behavior of dust aggregates is therefore essential. It is known that the main energy dissipation mechanisms are the tangential frictions between particles in contact, namely, rolling, sliding, and twisting. However, there is great uncertainty for the strength of rolling friction, and the dependence of the collisional growth condition on the strength of rolling friction was poorly understood. Here we performed numerical simulations of collisions between two equal-mass porous aggregates with various collision velocities and impact parameters, and we also changed the strength of rolling friction systematically. We found that the threshold of the collision velocity for the fragmentation of dust aggregates is nearly independent of the strength of rolling friction. This is because the total amount of the energy dissipation by the tangential frictions is nearly constant even though the strength of rolling friction is varied.

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Collisions between ice-covered silica grains: An atomistic study

Cited by 14 publications

References 53 publications

Bouncing and spinning of amorphous Lennard-Jones nanoparticles under oblique collisions

Bouncing and spinning of amorphous Lennard-Jones nanoparticles under oblique collisions

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

Collisional Growth Efficiency of Dust Aggregates and Its Independence of the Strength of Interparticle Rolling Friction

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