Research Projects

Compound particles—a solid core encapsulated in a fluid droplet (figure on the left)—serve as powerful model systems for studying the mechanics of core–shell structures. In our work, we investigate how confinement, fluid properties, and background flow influence their dynamics and morphology. We examine both passive systems (with inert cores) and active ones (where the core generates flow or stress - microswimmers), using the framework of low Reynolds number hydrodynamics. The hydrodynamic interactions between the solid core and its surrounding fluid shell play a key role in shaping the particle’s behavior—and in turn, strongly influence the suspension’s overall flow response, often leading to complex, viscoelastic behavior. 

Microswimmers are self-propelled particles that move through viscous fluids by generating flow fields around themselves, typically at low Reynolds numbers where viscous forces dominate. Two minimal models illustrate this behavior: active droplets, driven by internal chemical reactions, and squirmers (figure on the left), which propel via surface slip. These systems offer a tractable way to explore how confinement, curvature, and external flow influence locomotion, deformation, and interactions. These simplified models provide insights into the fundamental physics of active transport and collective dynamics in complex environments—relevant to both biological processes and the design of synthetic swimmers.

Active nematics are nonequilibrium materials made up of elongated, energy-consuming units that generate spontaneous flows and give rise to dynamic topological defects (red and cyan markers on the figure on the left). In biological settings, these systems often consist of a mix of motile (yellow fluid) and non-motile cells (green fluid), making them inherently biphasic. Our research investigates how such mixtures reorganize through the motion, interaction, and segregation of defects. We focus on how activity, interfacial tension, and confinement shape defect dynamics and lead to charge segregation across active–passive boundaries. These studies provide a minimal yet powerful framework for understanding pattern formation, self-organization, and mechanical coordination in heterogeneous cellular systems. 

Epithelial tissues are dense, sheet-like assemblies of cells that exhibit collective behaviors such as coordinated flow, morphogenesis, and homeostasis. This research employs the cell vertex model (figure on the left) to understand how these dynamics emerge from the interplay of intracellular activity, intercellular forces, and external constraints like confinement. In particular, we explore how nematic order—arising from the elongated shape and alignment of cells—drives collective motion and defect dynamics in epithelial layers. We investigate how internal dissipation enables sustained flows in free-standing tissues, and how local rules for cell growth, division, and removal establish homeostatic steady states. By bridging cellular and tissue scales, this work provides insight into fundamental biological processes, including embryonic development, wound healing, and the mechanical regulation of tissue architecture.