Executive Summary : | The field of active matter has been rapidly growing for the past decade because active systems exhibit many statistical and dynamical properties that are not found in conventional nonequilibrium systems like sheared flow. Some of these properties are as follows: giant number fluctuations, motile topological defects, motility-induced phase separation and band formation. The active systems having a microscopic source of energy is the fundamental origin of these properties. Here, our focus is on the systems of the granular particles sprinkled on a vertically vibrating plate; the vibrated granular particles are active because they move in the horizontal plane due to the kicks by the vibrating plate. We have been studying the dynamics of motile rods moving through the monolayer of spherical beads confined between two vertically shaking plates. Our system exhibits a few interesting phenomena such as order-disorder transition as the bead concentration is increased, rod-bead segregation at high densities, and attraction between motile rods due to the elastic nature of the crystalline bead medium at high densities. In this problem, the bead medium behaves like an isotropic medium. We are now curious about the dynamics of motile particles in an anisotropic medium. Here, we propose to study the dynamics of motile rods moving through a monolayer of the nonmotile rods having fore-aft symmetry. The nonmotile rod keeps shuffling forth and back along its axis, thus diffusing but achieving no net displacement. Since the medium of nonmotile rods can be found in nematic as well as in the smectic phase at high concentration of the rods, it would be interesting to see how the anisotropic nature of the medium influences the collective dynamics and order-disorder transition of the motile rods and the interaction between two motile rods. We may observe additional Goldstone mode in our system when the medium is in its nematic phase, due to the symmetry broken by the medium. With this project, we would also be able to learn how a motile rod interacts with the topological defects in the nematic phase of the medium. We will use the particle dynamics simulation method to simulate our system and construct theoretical models to understand our findings. We will also collaborate with the experimental groups to verify our results. |