Fragmentation and energy dissipation in collisions of polydisperse granular clusters

Context. Dust aggregates consist of polydisperse grains following a power-law size distribution with an exponent of around 2.5, called the Mathis-Rumpl-Nordsieck (MRN) distribution. Aims. We compare the outcome of collisions between polydisperse granular aggregates with those of monodisperse aggregates. Methods. Granular-mechanics simulations were used to study aggregate collisions. Results. Both with respect to the fragmentation threshold and to energy dissipation, MRN aggregates behave as monodisperse aggregates if their size corresponds approximately to the geometric mean of the largest and smallest radius of the MRN distribution. Conclusions. Our results allow the polydisperse aggregates to be substituted with monodisperse aggregates, which are easier to simulate