Modeling the interaction of convex solidifying interfaces with spherical particles

CARLOS SCHVEZOV; ELIANA MABEL AGALIOTIS; MARIO ROSENBERGER; ALICIA ARES

Beijing

Conferencia; The 16th International Conference on Crystal Growth(ICCG-16); 2010

International Union fort Crystal Growth

The interaction of a foreign particle with a solidifying interface which produces the phenomenon of pushing ismodeling numerically. This phenomenon is known to be affected by fluid flow, thermal field, solute field and thenature 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 interfaceshape 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 fluidfield calculations are made in a decoupled way determining first the shape of the interface, and then the twomain forces acting during pushing; the drag and repulsion forces are modelled. The thermal and fluid flow fieldswere calculated using finite element methods.Both, the drag and repulsion forces are integrated at each step and compared until both are equal and the steadystate of pushing is reached. The pushing force is integrated using the Casimir-Lifshitz-van der Waalsinteraction. It was found that the model predicts the equilibrium distance in a steady state of pushing fordifferent sizes of particles and a convex solidifying interface. It is shown that the separation equilibriumdistance for a convex interface with respect to an ideal planar interface results in a larger solidification velocityfor trapping. The model results were in good agreement with experimental results for the critical velocityreported in the literature.