Flow-induced changes of the morphological stability in directional solidification: Localized morphologies

L. Bühler*, S. H. Davis

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

Steady, two-dimensional cellular convection is impressed upon a solid-liquid interface undergoing directional solidification. When the wavelength 2π/α of the convection is very long compared to that, 2π/β, of the morphological instability, the interface is sheared by "parallel" remote flow periodic in the flow direction. When the shear is taken to be constant instead of spatially periodic, a new formulation shows how a whole family of shear flows can be analyzed in a common way and how the physical mechanisms can be understood. When the shear is spatially periodic, two new modes of response are identified. For α/β small and for small flow speed the morphological instability becomes localized near converging stagnation points. At threshold the instability is steady and a localized wave packet contains many morphological cells. For α/β not so small or for larger flow magnitudes, the morphological instability becomes localized near mid-points between stagnation points and the unstable interface pattern is travelling within a stationary envelope.

Original languageEnglish (US)
Pages (from-to)629-647
Number of pages19
JournalJournal of Crystal Growth
Volume186
Issue number4
DOIs
StatePublished - Mar 7 1998

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Inorganic Chemistry
  • Materials Chemistry

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