Fluid Dynamics/ITS Seminar: Evan Variano, University of California at Berkeley
(this is a regularly-scheduled Institute for Theoretical Science seminar)
Title: Turbulent transport of non-spherical suspended particles: particle shape, size and rotation
Date: Tuesday, April 26, 2016
Time: 4 pm to 5 pm
Location: ITS Conference Room, 472 Willamette Hall
Evan Variano is an associate professor at UC Berkeley in the Department of Civil and Environmental Engineering. His research interests span transport and mixing in flows inspired by environmental processes, often at the intersection of Ecology and Fluid dynamics.
Abstract:
Natural particles suspended in water are often non-spherical. We explore the ways in which particle size and shape affects particle motion, focusing on particle parameters relevant for plankton, sediment aggregates, or autonomous vehicles. We find that shape has only a very weak effect on particle angular velocity, which is a quantity calculated with respect the global reference frame (i.e. east/north/up). If we analyze rotation in a particle’s local frame (i.e. the particle’s principle axes of rotation), then particle shape has a strong effect on rotation. In the local frame, rotation is described by two components: tumbling and spinning. We find that rod-shaped particles spin more than they tumble, and we find that disc-shaped particles tumble more than they spin. These preferential rotations, as well as total angular velocity, decrease with increasing particle size. Such behavior is indicative of how particles respond to the directional influence of vortex tubes in turbulence, and such response has implications for particle motion other than rotation. Understanding particle alignment is relevant for predicting particle-particle collision rates, particle-wall collision rates, and the shear-driven breakup of aggregates. We discuss these briefly in the context of what can be concluded from the rotation data discussed above.
More information: Evan’s website.
Please email Leif Karlstrom if you would like to schedule a meeting with Evan during his visit.