CAREER: Unsteady inertial dynamics of suspensions: transport, assembly and propulsion

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Controlling the movement of microscopic particles suspended in a liquid is important in a variety of technical applications, including the manipulation of cells in medical and analytical devices, the assembly of particles into structures and specialized materials, and the development of self-propelled particles. This CAREER award will support development of new simulation methods to predict and control particle motion that is driven by rapid oscillations of the suspension. The project will simulate individual particles, pairs of particles and, ultimately, assemblies of particles, taking into account the way interactions among the particles influence their motion. An array of educational activities aimed at K-12, undergraduate and graduate students, especially those from underrepresented groups, will be integrated into the project. Demonstrations of principles encountered in the research will be disseminated to the public through the Ameal Moore Nature Center, and high-school students will participate through hands-on projects that are integrated into training modules for teachers.The goal of this CAREER project is to develop a fundamental understanding of transport, assembly and propulsion in time-periodically driven particulate suspensions. This will be achieved using asymptotic theory, particle-dynamics simulations, and laboratory experiments. The investigators will first develop a nonlinear theoretical framework for particulate suspension dynamics under oscillatory flow, by invoking the separation between fast and slow timescales, and accounting for visco-inertial hydrodynamic interactions. Laboratory experiments will study how vibrated suspensions assemble into planar and three-dimensional structures under confinement. The assembly dynamics and the resulting structures will be interpreted using particle simulations. Finally, the researchers will use theoretical and computational techniques to investigate the role of inertia in self-propulsion, where oscillatory flow is excited by undulations of the body of the swimmer. Thus, the project will identify and quantify the mechanisms controlling the flow of passive and active particulate suspensions under oscillatory excitation. The fundamental scientific advances of the project and its potential applications are expected to inspire new control strategies for particle assembly and prompt further research on inertial particulate flows.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.