I investigate how collective behaviors emerge from self-motility and local interactions among active particles. Using a hydrodynamic theory of active particles, I showed that complex pattern formation of bacterial colonies can be explained by the interplay of logistic growth, crowding effect and alignment interaction. Using computer simulations, I discovered spontaneous aggregation and segregation of active particles induced by confinement and steric repulsion. By explicitly coarse-graining a self-propelled particle model with alignment interaction and rotational inertia, I developed a hydrodynamic theory for collectively turning flocks.
While the dynamics of active particle are being extensively studied, the energetic aspect of these systems remain poorly characterized. My future objective is to explore the impact of energy dissipation on self-organization of active particles.