59. Numerical modelling of the interaction of spherical particles with an advancing convex solidifying front

AGALIOTIS, E. M.; MARIO ROBERTO ROSENBERGER; SCHVEZOV, C. E.; ARES, A.E.

Rio de Janeiro

Conferencia; ICAM 2009; 2009

MRS

A moving solidifying front interacts with a steady solid particle in the melt producing what is normally called as pushing. When the particle has a different thermal conductivity than the solid and melt the interface could adopt a convex or concave shape if the particle has a smaller or larger conductivity, respectively. In the present report the case of particles generating a convex interface is considered. The two main forces acting during pushing are the drag and the pushing forces. The calculations are made in a decoupled way determining first the shape of the interface then the drag force and also the pushing force. The thermal and fluid flow fields were calculated using the finite element methods assuming the system is axis-symmetric. Both, the drag and pushing 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.  The steady state of pushing is characterized by a separation distance between particle and interface which decreases with the solidifying velocity. The results are compared with those obtained for the case of planar interfaces which is obtained for systems with the same thermal conductivity. As a result it is shown the reduction of equilibrium separation distance for a convex interface with respect to a planar interface which results in a larger solidification velocity for trapping. The magnitude of the effect of the different parameters in the phenomenon is presented and discussed.