Title: Flow-Induced Morphology
Speaker: Dr. Yi-Ju Chen
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Abstract:
During the directional solidification of a binary mixture, the planar solid-liquid interface becomes unstable when the pulling speed is greater than a critical value. This instability is modified by a cellular convective field in the liquid phase that redistributes solute concentration. The resulting system is a Floquet problem with multi-degrees of freedom in space. When the flow is weak the induced morphology is incommensurate with the flow periodicity, but as the flow gets stronger, the instability becomes localized and confined in narrow envelopes arrayed on the crystal plane. The stability boundaries are computed numerically for various flow patterns. Their asymptotics are delivered through WKB-type analyses.Date: Friday, September 24, 1999