UNH Ocean Seminar

Bouyant, Non-Spherical Particles in Wind-Driven Turbulance

Luci Baker, Ph.D.
Postdoctoral Scholar

Dept. of Mechanical Engineering
University of Washington

Friday, Feb. 4, 2022, 3:10pm
Chase 105

Despite the ubiquity of microplastic particles in the oceans, the lifetimes and fates of these plastics are largely unknown. One pathway of removal relevant to floating microplastics is that of chemical degradation by exposure to sunlight, which is dictated by both the depth and, for non-spherical microplastics, orientation of the particles in the water column. Positively buoyant particles exist near the ocean surface, but wind produces waves and turbulence which mix particles down in the water column. Here, experiments are performed in a laboratory wind-wave channel over a range of wind speeds relevant to the ocean surface. Positively buoyant rod-, disk-, and sphere-shaped high-density polyethylene (HDPE) particles are seeded in the flow, and their transport and dispersion are measured using a novel particle shadow tracking technique. A large field of view facilitates the tracking of particles over long times. The parameter space of non-spherical, non-tracer particles in wind-driven turbulence is systematically explored, and both Eulerian and Lagrangian statistics of particle depth and orientation are obtained. The results will provide insight into the physical processes governing microplastic particle transport and fate in the ocean.


Luci is a postdoc in Mechanical Engineering at the University of Washington in Seattle. She is currently working with Michelle DiBenedetto to investigate vertical mixing of microplastic particles by wind-driven turbulence in the ocean surface boundary layer through laboratory experiments and numerical models. Originally from Minnesota, she received her bachelor's, master's, and PhD in Aerospace Engineering and Mechanics from the University of Minnesota, where she worked with Filippo Coletti to experimentally explore fluid-particle interactions in turbulence.