Ice crystals under terrestrial and microgravity conditions: Experiments versus theory for tip velocity and tip radius

Based on a number of experiments carried out in microgravity and terrestrial conditions, we demonstrate that the shape of ice dendrite tips sufficiently differs from an elliptical paraboloid. To describe the stable growth mode of such crystals, we apply Geometrically Morphological Theory (Acta Mater. 296 (2025), 121232), Boundary Integral Method (Physica A 469 (2017), 420) and Selection Criterion (Phys. Rep. 1085 (2024) 1). This enables us to theoretically obtain the dendrite tip velocity V and tip radius R 1 in the basal plane during the same experiment as the functions of liquid undercooling. Analyzing all available experimental data on the measurements of V and R 1 , we determined the integration limit in the heat balance equation and showed that it is close to 0 . 2 R 1 for the tips of ice crystals grown in undercooled normal and heavy water. We show that our approach corresponds to the solvability theory within the scatter of the experimental data for the selection criterion in the basal plane. In general, the developed approach describes all the experimental data in microgravity and on the ground known to us on the growth of ice crystals, where simultaneous measurements of V and R 1 were performed.