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MM: Fachverband Metall- und Materialphysik

MM 12: Postersitzung I

MM 12.33: Poster

Montag, 14. März 2011, 17:30–19:00, P5

A study of ice crystal growth based on diffuse interface modeling using extended anisotropy formulations — •Marcel Huber, Frank Wendler, and Britta Nestler — Institute of Materials and Processes, Karlsruhe University of Applied Science, Moltkestr. 30, 76133 Karlsruhe, Germany

Though a phenomenon of daily experience, the precise description of ice crystal growth is still lacking. Progress in technical application like ice slurry for cooling, cryodesiccation and freeze casting process in the synthesis of porous ceramics motivate further research. In this work we study equilibrium and off-equilibrium growth of ice crystals in pure water. The solid interfaces evolve due to an interplay of a driving force (pressure change or undercooling) and interface anisotropies with a normal velocity depending on chemical potential, kinetic coefficient and surface stiffness. To define the location of each ice-crystal (of different orientation) and the phase in the computational domain, we introduce non-conserved order parameters, so that the equation for the velocity can implicitly be solved by using a phase-field model of Allen-Cahn type. We pay special attention to the definition of an adequate anisotropy formulation for interface energies and kinetics. We present numerical studies of various formulations including expansions with respect to cubic harmonics and compare the resulting growth shapes under equilibrium conditions to experimental observation. Using these findings, simulations of strongly undercooled dendritic growth of ice are carried out, where the thermal field is also solved in the domain to account for the transport of latent heat.