Influence of porosity on high-velocity mass-asymmetric collisions

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

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Año: 2020 vol. 492 p. 1937 - 1946

0035-8711

Using granular mechanics, we study the influence of porosity on the collisions of spherical granular aggregates with a mass ratio of around 60. At high filling factors, the projectile produces a crater on the target, similar to impacts on a granular bed. However, at low filling factors, the small projectile passes through the large target, strongly fragmenting it. By a consideration of the lateral grain velocities during the collision, we attribute this behaviour to the ´piston effect´, in which the projectile loses momentum mainly to the grains below it. Due to an increase in grain-grain interactions as porosity decreases, the piston effect loses its importance for higher filling factors, φ ≿ 0.2. These results may prove useful in modelling collisions occurring in debris discs.