On the stickiness of CO$_{2}$ and H$_{2}$O ice particles

TL;DR

This study investigates why CO$_{2}$ ice particles are less sticky than H$_{2}$O ice particles, revealing that differences in viscoelastic dissipation, rather than surface energy, explain the disparity in sticking behavior.

Contribution

The paper demonstrates that the difference in ice particle stickiness is primarily due to variations in viscoelastic dissipation, influenced by the viscoelastic relaxation time, using a contact model.

Findings

CO$_{2}$ ice particles' sticking threshold matches elastic sphere predictions.

H$_{2}$O ice particles' sticking threshold exceeds elastic predictions.

Viscoelastic dissipation strength explains the stickiness difference.

Abstract

Laboratory experiments revealed that CO$_{2}$ ice particles stick less efficiently than H$_{2}$O ice particles, and there is an order of magnitude difference in the threshold velocity for sticking. However, the surface energies and elastic moduli of CO$_{2}$ and H$_{2}$O ices are comparable, and the reason why CO$_{2}$ ice particles were poorly sticky compared to H$_{2}$O ice particles was unclear. Here we investigate the effects of viscoelastic dissipation on the threshold velocity for sticking of ice particles using the viscoelastic contact model derived by Krijt et al. We find that the threshold velocity for sticking of CO$_{2}$ ice particles reported in experimental studies is comparable to that predicted for perfectly elastic spheres. In contrast, the threshold velocity for sticking of H$_{2}$O ice particles is an order of magnitude higher than that predicted for perfectly elastic spheres. Therefore, we conclude that the large difference in stickiness between CO$_{2}$ and H$_{2}$O ice particles would mainly originate from the difference in the strength of viscoelastic dissipation, which is controlled by the viscoelastic relaxation time.