Collisions between micro-sized aggregates: role of porosity, mass ratio, and impact velocity

PLANES, MARÍA BELÉN; MILLÁN, EMMANUEL N; URBASSEK, HERBERT M; BRINGA, EDUARDO M

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Año: 2021 vol. 503 p. 1717 - 1733

0035-8711

Dust aggregate collisions usually occur between mass-asymmetric collision partners. Granular-mechanics simulations are usedto study the influence of filling factor,φ, and impact velocity in collisions of spherical granular aggregates with different values oftheir mass ratio, but the same filling factor. Three possible outcomes are observed: (i) sticking, which might include penetrationof the smaller aggregate into the larger aggregate; (ii) fragmentation of the largest aggregate into two large fragments, particularlydue to the so-called piston effect for low filling factors; and (iii) total destruction of the aggregates. Most of the impact energyis spent by friction, with some fraction leading to compaction of the porous material. The erosion efficiency varies significantlywith impact velocity, mass ratio, and porosity, but the accretion efficiency does not show such strong variations. For highlyasymmetric collisions with high impact velocities (100 m s−1), grain accretion (growth) can occur for a ?window? in the fillingfactor (0.20<φ<0.35). This window becomes wider as the impact velocity decreases. As the mass ratio of the aggregatesdecreases, the impact velocities that enable growth can also decrease. The mass distribution of the fragments follows a power-lawdistribution that is almost independent of the mass ratio, filling factor, and velocity