The goal of the proposed research is to investigate with both experiments and computations the behavior of complex, anisotropic active fluids. Active fluids are fluids that behave in unique ways, because of the presence of active particles that can self-assemble, or can move and pack in different ways, giving different macroscopic properties to the fluid. The proposed research can uncover novel phenomena that could be exploited for design new fluid materials that are responsive to their external environment.
Past studies have focused largely on the physics of "active colloids" in isotropic Newtonian fluids, yet many future applications of active fluids would require an understanding of their behavior in complex fluids. This is the white space that this proposal covers: how anisotropy in the viscoelastic properties of a fluid can impact fundamental transport phenomena involving active colloids. A first research thrust will focus on the effect of the anisotropic environment of a liquid crystal suspension has on the diffusivity of a self-propelled particle within the suspension. Specifically, Brownian Dynamics (BD) simulations will be combined with experiments involving tracking of single self-propelled colloidal Janus particles at the interface of a nematic liquid crystal. A second thrust will focus on the effects of a suspension of active particles hosted within an anisotropic fluid on the diffusion of passive tracer particles. Motile bacteria dispersed within biocompatible liquid crystals will be used to explore how passive particles diffuse in the presence of the motion of the rod-shaped bacteria. The overall outcome of this integrated program of experiment and simulation will be new knowledge regarding fundamental transport processes driven by internally generated gradients in complex fluids. The collaborating group will establish a collaboration with the Teacher Preparation Program at the University of Puerto Rico Mayaguez to develop, disseminate and assess bilingual educational modules. Educational activities are proposed to expose students to cross-cultural educational experiences and to prepare them to work in diverse settings. An interdisciplinary class on soft matter will be offered to students at both institutions.
