Abstract/Summary

The terminal velocity vt and preferred orientations of ice particles has been investigated using 3D-printed analogues sedimenting in glycerine solutions at Reynolds numbers typical of natural ice particles falling in air. Twenty two different particle geometries were investigated: these included both simple shapes, such as hexagonal plates, as well as more complex particles, such as bullet rosettes, plate-polycrystals and aggregates. Two widely-used prescriptions for ice particle fall speed were tested against the new experimental data, to determine the accuracy of their predictions. We show that for open particles, such as bullet rosettes and aggregates, one of these prescriptions systematically overestimates vt, by as much as 80%.