Dust-aggregate impact into granular matter: A systematic study of the influence of projectile velocity and size on crater formation and grain ejection

PLANES, M. B.; MILLAN, E. N.; URBASSEK, H. M.; BRINGA, E. M.

ASTRONOMY AND ASTROPHYSICS

EDP SCIENCES S A

Año: 2017

0004-6361

Context. Dust impact into granular materials leads to crater formation and material ejection.Aims. The impact of dust aggregates, composed of a number N p of grains, into a granular bed consisting of the samegrains is studied as a function of impact velocity v and projectile size Np. No gravitational effects are included.Methods. Granular-mechanics simulations are used to study the outcome of dust-aggregate impacts. The granular bedand the aggregates are composed of silica grains and have filling factor 0.36.Results. Both the crater volume and the ejection yield increase sublinearly with total impact energy. No crater rimsare formed. Crater shapes change from hemispheric to elongated when increasing either projectile size or velocity. Thecrater walls are compacted by the impact within a zone of a size comparable to the crater radius.Ejecta are produced at the edges of the impact; only a small fraction of the ejecta stem from the projectile. The energy2distribution of the ejecta follows at high energies a 1/E decay reminiscent of sputtering from atomic targets. Themaximum of the distribution is shifted to higher energies for larger projectiles; this is caused by the increasing depthfrom which ejected grains originate.Conclusions. Due to the dissipative nature of intergranular collisions and the porosity of the target, crater morphologyand ejecta yield deviate characteristically from impacts into atomic materials.