Theory and computation of directional nematic phase ordering

EZEQUIEL R. SOULÉ; NASSER M. ABUKHDEIR; ALEJANDRO D. REY

PHYSICAL REVIEW E - STATISTICAL PHYSICS, PLASMAS, FLUIDS AND RELATED INTERDISCIPLINARY TOPICS

American Physical Society

Año: 2009 vol. 79 p. 21702 - 21702

1063-651X

A computational study of morphological instabilities of a two-dimensional nematic front under directionalgrowth was performed using a Landau–de Gennes-type quadrupolar tensor order parameter model for thefirst-order isotropic-nematic transition of 5CB pentyl-cyanobiphenyl. A previously derived energy balance,taking anisotropy into account, was utilized to account for latent heat and an imposed morphological gradientin the time-dependent model. Simulations were performed using an initially homeotropic isotropic-nematicinterface. Thermal instabilities in both the linear and nonlinear regimes were observed and compared to pastexperimental and theoretical observations. A sharp-interface model for the study of linear morphologicalinstabilities, taking into account additional complexity resulting from liquid-crystalline order, was derived.Results from the sharp-interface model were compared to those from full two-dimensional simulation identifyingthe specific limitations of simplified sharp-interface models for this liquid-crystal system. In the nonlinearregime, secondary instabilities were observed to result in the formation of defects, interfacial heterogeneities,and bulk texture dynamics.