Sharp-Interface Theory for Transitions Between the Isotropic and Uniaxial Nematic Phases of a Liquid Crystal
Eliot M. Fried
Washington University in St. Louis, Department of Mechanical and Aerospace Engineering
Thursday, May 3, 2007 15:00-16:00,
Building 101, Lecture Room B
Gaithersburg
Thursday, May 3, 2007 13:00-14:00,
Room 4550
Boulder
Abstract:
A sharp-interface theory has been developed to describe material
interfaces between nematic and isotropic fluids. That theory
accounts for flow, director elasticity of the nematic fluid, and
anchoring energy at the interface. In this talk, we describe the
extension of that theory to account for phase transformations
between the isotropic and nematic phases of a liquid crystal. Such
transformations involve the growth of one phase, nematic or
isotropic, at the expense of the other--as described by the
migration of the interface with respect to the underlying fluid. Of
fundamental importance in the theory is a supplemental evolution
equation arising from the notion of configurational momentum balance
and accounting for the microphysics underlying the exchange of
material between the phases. This equation provides an appropriate
generalization of the Gibbs-Thomson relation familiar from theories
for dendritic solidification. As an application, we study the
behavior a spherical isotropic droplet surrounded by a radially
oriented uniaxial nematic phase. Our generalized Gibbs-Thomson
relation then reduces to a nonlinear ordinary differential equation.
In addition to describing many essential features of
isotropic-nematic phase transformations, this equation yields
insight concerning the occurrence and stability of isotropic cores
for hedgehog defects in nematic liquid crystals.
Speaker Bio:
Eliot Fried is a Professor in the Department of Mechanical and Aerospace Engineering
at Washington University in St. Louis.
He received his PhD in Applied Mechanics from California Institute of Technology in 1991.
His research interests include the mechanics of novel polymeric materials, molecular dynamics simulations of granular materials,
and epitaxial growth in phase transitions.
Professor Fried's publications have appeared in the Journal of Fluid Mechanics, Physical Review E,
and the SIAM Journal on Applied Mathematics.
Presentation Slides: PDF
Contact: G. B. McFaddenNote: Visitors from outside NIST must contact
Robin Bickel; (301) 975-3668;
at least 24 hours in advance.
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