Microscopic particles and droplets tend to arrange themselves into regular patterns when suspended in a nematic liquid crystalline matrix. Using numerical simulations, we are investigating the interaction between such particles and the anisotropic matrix, especially through the nucleation of orientational defects. Dynamic simulations have shown the formation of lines resembling experimental observations (see graphics below). Our ongoing work focuses on achieving multi-dimensional patterns, and the possibility of using the self-assembly as a method for making photonic crystals with tunable bandgaps.
In addition, we have studied how the macroscopic flow field affects the defect configuration in return. In dynamic simulations of drop motion in a Leslie-Ericksen nematic, we predicted that on a translating drop, a Saturn ring defect will be "convected" downstream. If the drop velocity is sufficiently high, the ring will be ejected from the drop into the wake and turn into a hedgehog point defect. This has since been confirmed by experimental observations. The images below illustrates the transformation process.