校级学术报告(偏微分方程讨论班)
Title:Defect Dynamics near Bubbles and Drops Rising in a Liquid Crystalline Medium
Speaker: James J. Feng
Department of Mathematics and
Department of Chemical and Biological Engineering
University of British Columbia, Canada
时间：2007年4月27日（周五）下午3：30-4：30
地点：理科大楼A510
Abstract
Owing to their molecular orientation, nematic liquid crystals exhibit complex rheological behavior. In particular, their tendency to anchor on interfaces at a fixed angle leads to unusual interfacial dynamics for drops and bubbles. In this talk, I describe numerical simulations of rising drops in a quiescent nematic medium with a vertical far-field orientation. The moving interface is
computed in a diffuse-interface framework, and the anisotropic rheology of the liquid crystal is represented by the Leslie-Ericksen theory, regularized to permit topological defects. Results reveal interesting coupling between the flow field and the orientational field surrounding the drop, especially the defect configuration. The flow sweeps a point or ring defect downstream, and may transform the ring defect into a point defect. The nematic orientation affects the flow field in return, and modifies the rise velocity and drag on the drop. The drop takes on unusual shapes when the anchoring energy is high enough to compete with the interfacial tension.
