Bulletpack: A Fast, Flexible Packing Algorithm for Particulate Media

We introduce a new particle packing code that mimics the process used to fabricate particulate media. It achieves realistic packing fractions, with values well above 40%, and high computational efficiency for nearly arbitrary particle shapes and distributions of geometric and magnetic properties. We perform recording simulations in combination with a modified version of the Magpar micromagnetic code to illustrate the importance of realistic packing. We find for the case of non-oriented platelets that the broadband signal-to-noise ratio drops by 1 dB when the packing fraction is reduced from 43% to 30%; this result is in agreement with scaling models.