Incorporating Surface Diffusion into a Cellular Automata Model of Ice Growth from Water Vapor

We describe a numerical model of faceted crystal growth using a cellular automata method that incorporates admolecule diffusion on faceted surfaces in addition to bulk diffusion in the medium surrounding the crystal. The model was developed for investigating the diffusion-limited growth of ice crystals in air from water vapor, where the combination of bulk diffusion and strongly anisotropic molecular attachment kinetics yields complex faceted structures. We restricted the present model to cylindrically symmetric crystal growth with relatively simple growth morphologies, as this was sufficient for making quantitative comparisons between theoretical models and ice growth experiments. Overall this numerical model reproduces ice growth behavior with reasonable fidelity over a wide range of conditions, albeit with some limitations. The model could easily be adapted for other material systems, and the cellular automata technique appears well suited for investigating crystal growth dynamics when strongly anisotropic surface attachment kinetics cause faceted growth morphologies.