Transient dynamics of a cellular front instability during directional solidification

Abstract

We report the first systematic transient dynamics measurements of a cellular instability during directional solidification on a nematic-isotropic interface of the liquid crystal 8cB. The time evolution of the most unstable spatial mode of the interface is well described by a third-order Landau-amplitude equation, as anticipated theoretically. Instability growth rates and nonlinear cubic coefficients are measured as a function of pulling velocity and temperature gradient. The results are compared with theories of directional solidification.