The growth of a free dendrite into a supercooled liquid is simulated through a modified version of the phase-field model, which takes into account the advection flow due to the different densities ρs and ρl of the solid and liquid phases. The intensity of the flow is maximal at the dendrite tip and decays far from the surface of the crystal. At fixed undercooling, as the density ratio ρs/ρl increases, we observe a decrease of the tip velocity, while the tip radius increases. The Peclet number is shifted with respect to the pure diffusive value. The onset of the morphological instability, which is responsible for the origin of the dendrite from a growing circular germ, is slightly anticipated by the flow effects.
Advection flow effects in the growth of a free dendrite
CONTI, Massimo
2004-01-01
Abstract
The growth of a free dendrite into a supercooled liquid is simulated through a modified version of the phase-field model, which takes into account the advection flow due to the different densities ρs and ρl of the solid and liquid phases. The intensity of the flow is maximal at the dendrite tip and decays far from the surface of the crystal. At fixed undercooling, as the density ratio ρs/ρl increases, we observe a decrease of the tip velocity, while the tip radius increases. The Peclet number is shifted with respect to the pure diffusive value. The onset of the morphological instability, which is responsible for the origin of the dendrite from a growing circular germ, is slightly anticipated by the flow effects.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
