Previous abstract
Next abstract
Session Q02 - Mechanisms for Pattern Formation.
Invited session, Friday morning, March 24, 8:00
Ballroom A2, San Jose Convention Center
Since the original linear stability analysis of a crystal-melt interface during directional solidification was performed by Mullins and Sekerka 35, 444 (1964)., many experiments have explored both the initial instability and the planar-cellular-dendritic pattern evolution dynamics, with mixed results. Among the difficulties encountered in comparing experiments and theory are: (1) failure of the system to reach steady state before undergoing a morphological instability, (2) subcritical nature of the initial bifurcation, and (3) failure to identify a selection mechanism for the steady-state dendritic pattern. Recent new theoretical approaches proposed by Warren and Langer 3518 (1990); Phys.\ Rev.\ E 47, 2702 (1993). have opened a new route to analyzing such experiments. We will review recent experimental studies of the initial transient response, the planar-cellular instability, and subsequent evolution of dendritic arrays in plastic crystals containing small concentrations of laser dye. In collaboration with W. Losert, B.Q. Shi, D. Liu, and L.M. Williams. * Supported by DOE Grant DE-FG02-84-ER54132.