Abstract
Internally driven, or active materials are a special class of non-equilibrium system that inspire scientists across various disciplines. In condensed matter physics, this class of problems are a natural extension to equilibrium statistical mechanics; In biophysics, active matter is a testing ground for unifying theories of the mechanics of life; In material science and engineering, active matter presents new opportunities to design novel self-animating materials. Active nematics, or self driven nematic liquid crystals, are a widely studied instance of active matter, due to their spectacularly rich phenomenology and potential for practical applications. In the past, research on active nematics had been restricted to 2D. A full 3D treatment of active nematics presents several challenges. Over the past five years, we have made significant progress in addressing these challenges with extended collaboration between theory, experiment, and numerical simulations. This thesis documents some of these developments.
Results presented here demonstrate that three dimensional active nematics are strikingly different from their two dimensional counterparts. The possibility of `escape into the third dimension' implies that the topology of a 3D nematic is fundamentally different from its 2D counterpart. Active driving of a 3D nematic leads to deformations of the twist kind that are not possible with just two dimensions. Additionally, the effects of confinement in 3D are fundamentally different from that in 2D, since confinement in different dimensions get coupled through the hydrodynamics.