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Department of Estuarine and Ocean Sciences PhD Proposal Defense Announcement - by Bailey J. Avila

When: Monday, June 6, 2022
10:00 AM - 11:00 AM
Where: > See description for location
Description: The School for Marine Science and Technology
Department of Estuarine and Ocean Sciences
PhD Proposal Defense Announcement

"Vortices and Energetics in the Ocean, from Climate to Caudal"

Bailey J. Avila

Committee Members:
Dr. Miles Sundermeyer, SMAST, University of Massachusetts Dartmouth
Dr. Geoffrey Cowles, SMAST, University of Massachusetts Dartmouth
Dr. Banafsheh Seyed-Aghazadeh, Mechanical Engineering, University of Massachusetts Dartmouth
Dr. Kristina Kamensky, Naval Undersea Warfare Center - Newport
Dr. Marie-Pascale Lelong, North West Research Associates

Monday, June 6, 2022
10:00 am
SMAST East, Rooms 101/102
836 S. Rodney French Blvd, New Bedford, MA
And via Zoom

This dissertation aims to understand ocean energetics in two parts. The first part addresses energetics at the submesoscale and the importance of vortical mode. Globally, energy is put into the ocean from tides and wind, ultimately making its way down scale to dissipation. Understanding how and where this energy is transferred is critical for ocean global circulation models as they move to resolve mesoscale processes, and is a topic of ongoing study. In Chapter 1 numerical simulations will be used to study energy exchanges between internal waves and vortical mode, specifically identifying processes and the scales at which vortical mode is generated. A linear decomposition of model fields into internal wave and vortical mode components is used to explore energy exchanges both in physical space and spectrally. In physical space fluid parcels are tracked to study the modification of potential vorticity. Spectral analyses are further used to reveal cascades of energy both down- and up-scale due to internal waves and vortical mode, respectively. Results show that vortical mode appears across all scales everywhere internal waves are present, and that
nonlinear interactions may be a more important generation mechanism than turbulent dissipation, which was previously thought to dominate in the ocean interior.
The second part of this study will address the energetics and efficiency of fish locomotion. Swimming efficiency has been studied for decades with application to marine propulsion and biomimetics. Swimming fish extract and conserve energy by utilizing vortices around upstream bodies or by shedding their own vortices. Definitions of efficiency consider either the hydrodynamics and flow around the body of the fish contributing to thrust, or the mechanics and supply of energy to generate such motions (cost of transport). Chapter 2 will address the first definition concerning hydrodynamics. A parametric study to maximize Froude efficiency will be conducted for steady thunniform swimming using the numerical model, OpenFOAM. Parameters considered will include tail-beat frequency, amplitude, and wavenumber. Similar to what occurs in nature, simulations will optimize both Froude efficiency and cost of transport, with future application to biomimetic fish. Expanding on these findings, Chapter 3 will identify what signatures of pressure, vorticity, or drag around a steady, thunniform swimming fish characterizes efficient swimming. This will enable classification of whether a specific swimming motion is efficient or inefficient. The work in Chapters 2 and 3 will aid development of closed-loop control of biomimetic underwater vehicles.
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For additional information, please contact Sue Silva at
Contact: > See Description for contact information
Topical Areas: School for Marine Sciences and Technology, SMAST Seminar Series