Particle Migration in Complex Viscous Flows

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AbstractCTS-0334825J. McCarthy, U of PittsburghThis proposal is focused on the migration of non-neutrally bouyant particles in complexnon-Stokesian closed flows. This problem, important to issues ranging from materials processing to reactor design, has not been studied either computationally or experimentally, to our knowledge. The central hypothesis of the proposed work is that in these flows the variety of migration forces -- centrifugal and gravitational buoyancy; a variety of inertial lift forces (both with spin and without); and shear-induced migration when multiple particles are present -- can lead to a rich variety of asymptotic behavior. Furthermore, with recent advances in both experimental flow visualization as well as multi-phase Computational Fluid Dynamics (CFD), we believe that strong insight into particle migration in complex flows is now possible. In this work, we focus on the migration behavior of non-neutrally buoyant particles in two prototypical non-Stokesian closed flows: a cavity flow and a mixing tank. Specifically, the research will examine the trajectories and asymptotic locations of particles both computationally and experimentally, with the ultimate aim of uncovering the competition between migration modes such that control of asymptotic particle behavior may be possible.The broader impact of the work lies in integration of research and teaching, infrastructure development, and the fostering of partnerships. During the course of the project training will be provided for one full-time graduate student. Every effort will be made to recruit students from underrepresented groups to participate in this endeavor. Similarly, several undergraduate researchers will be involved in the form of an independent study (thus integrating research and teaching without requiring additional budgeted funds). The proposed work will enhance infrastructure through the generation of both the experimental data (as a metric of comparison for future work) as well as by comparing/validating several computational techniques for modeling particle migration in complex flows. It will foster partnerships by enabling future collaborative work between the PI and the National Energy Technology Laboratory. The intellectual merit of the proposal lies in gaining a better fundamental understanding of the migration forces relevant in complex viscous flows. At the completion of the project we will have advanced discovery and understanding through (1) establishing well-documented experimental results on particle migration in complex flows (2) validating pseudo-continuum and discrete modeling tools for examining these flows; and ultimately, (3) developing methodologies which exploit competing effects within these systems to yielda rational procedure for varying particle properties (size, shape, density), fluid properties (density, viscosity), and flow field/geometry such that the discrete elements within a flow migrate to well-defined predetermined positions.