Turbulent alterations to net settling rate of non-spherical particles

Tuesday, 15 December 2015
Poster Hall (Moscone South)
Evan A Variano1, Luca Brandt2, Mehdi Ardekani2, Lee Karp-Boss3 and Nimish Pujara1,4, (1)University of California Berkeley, Berkeley, CA, United States, (2)KTH Royal Institute of Technology, Mechanics, Stockholm, Sweden, (3)University of Maine, Department of Marine Sciences, Orono, ME, United States, (4)Cornell University, Ithaca, NY, United States
The rate at which particles sediment out of the surface mixed layer is a major control on carbon flux in the ocean. Turbulence can change the rate at which particles escape the mixed layer but mechanisms and magnitude of effects are not well understood for aquatic particles. Here we use a 3-pronged approach to study turbulence affects on sedimentation rates of non-spherical, marine-like particles. First, we apply an orientation-based kinematic model to track particles through turbulent flow. We then use a complex numerical model that solves the dynamical equation of motion for non-spherical particles embedded in turbulent flow. Finally we use a novel 3D particle-tracking tool to measure trajectories of diatoms in a turbulent flow and test predictions from numerical models. At the time of writing, preliminary results from numerical simulations indicate turbulent-altered settling for elongated (rod-shaped) particles at size, mass, and shapes similar to those measured for marine phytoplankton.