Modeling the interaction of convex solidifying interfaces with spherical particles

E. M. AGALIOTIS; M. R. ROSENBERGER; A. E. ARES; C. E. SCHVEZOV

Beijing, China

Conferencia; THE 16th INTERNATIONAL CONFERENCE ON CRYSTAL GROWTH (ICCG-16); 2010

ICCG-16

The interaction of a foreign particle with a solidifying interface which produces the phenomenon of pushing is modeling numerically. This phenomenon is known to be affected by fluid flow, thermal field, solute field and the nature of the particle, the melt and the solid material and affects the distribution of the particles in the melt. Particles with different thermal conductivities than the solid and melt produce a convex or concave interface shape for particles with smaller or larger conductivity than solidifying material, respectively. In the present report the case of particles generating a convex interface is considered. The thermal and fluid field calculations are made in a decoupled way determining first the shape of the interface, and then the two main forces acting during pushing; the drag and repulsion forces are modeled. The thermal and fluid flow fields were calculated using finite element methods. Both, the drag and repulsion forces are integrated at each step and compared until both are equal and the steady state of pushing is reached. The pushing force is integrated using the Casimir-Lifshitz-van der Waals interaction. It was found that the model predicts the equilibrium distance in a steady state of pushing for different sizes of particles and a convex solidifying interface. It is shown that the separation equilibrium distance for a convex interface with respect to an ideal planar interface results in a larger solidification velocity for trapping. The model results were in good agreement with experimental results for the critical velocity reported in the literature.