Abstract
Our work is motivated by the need to understand and predict turbulent particle-laden flows across a range of environmental and industrial applications. We consider a relatively canonical yet challenging experimental flow designed to be accessible to direct numerical simulation. A spherical particle in a turbulent boundary layer undergoes complicated particle-wall and particle-turbulence interactions. Particles with significant diameter are subject to variations in shear and normal forces around their circumference. Wall friction will affect the particle rolling and sliding motions while coherent flow structures can lift the particle away from the wall. To resolve the sphere dynamics in such a flow, 3D tracking experiments are conducted in a water channel facility. The translation and rotation of individual spheres released from rest was tracked over distances of 6d for multiple flow Reynolds numbers and particle-to-fluid density ratios. While neutrally buoyant particles typically lift off from the wall upon release, denser particles travel mostly along the wall. The relative contributions of turbulence, wall friction, and mean shear to the resulting particle motions will be discussed for the different cases considered.
Bio
Ellen Longmire is currently Associate Dean for Academic Affairs in the College of Science & Engineering at the University of Minnesota. She received an A.B. in physics (1982) from Princeton University and M.S. (1985) and Ph.D. (1991) degrees in mechanical engineering from Stanford University. She has taught and directed research in the Department of Aerospace Engineering and Mechanics at the University of Minnesota since 1990. Professor Longmire uses experimentation and analysis to answer fundamental questions in fluid dynamics that affect industrial, biomedical, and environmental applications. Her research interests include single- and multi-phase transitional and turbulent flows, interfacial effects in multi-fluid flows, and development of measurement and analysis techniques. She is a Fellow of the American Physical Society and received the UM Distinguished Women Scholars Award, the McKnight Land-Grant Professorship, and the NSF National Young Investigator Award. She currently serves as an Editor-in-Chief for Experiments in Fluids. She previously served as Chair of the American Physical Society Division of Fluid Dynamics, as a member of the US National Committee on Theoretical and Applied Mechanics, and as an Associate Editor for Physics of Fluids.
Host: Professors Tess Saxton - Fox & Jonathan Freund
