Impact of an ice particle onto a rigid substrate: Statistical analysis of the fragment size distribution

In the present work, the distribution of fragments that result from a normal impact of a temperature-controlled ice particle onto a dry, heated and rigid wall is investigated. For the first time, both particle and wall temperature are varied systematically, extending fundamentally the understanding of their role on the fragmentation outcome. Ice particle impact is examined for varying impact velocity, particle diameter, and particle and target temperature, and the impact and fragmentation process is captured using a high-speed video system. Individual fragment volumes are estimated using an in-house Kalman-filter algorithm. A maximum-likelihood estimation for a double-truncated power-law fit of the fragment volume distribution yields a characteristic value for the power-law exponent Ψ. A statistical method based on Monte Carlo simulations is carried out to determine the optimal truncation points. An analysis of variance allows the conclusion that for the range of studied parameters, only the effect of the impact velocity on the fragment distribution exponent Ψ is significant. Accordingly, the particle diameter, its temperature and the temperature of the target have been found to be without an effect on Ψ. In addition to the quantitative analysis, the present work contributes to a better understanding of the mechanisms controlling ice crystal icing also based on phenomenological observations of the impact process.