Numerical Modeling of Active Bacterial Reorientation & a Human-Scaled Force-Feedback Microbial Swimming Simulator
AuthorMavis, Isaac Wesley
AdvisorFu, Henry C
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This thesis contains two separate projects focused on low Reynolds number swimming. The first project aims to model recently observed V. alginolyticus flick reorientation maneuvers by utilizing the regularized Stokeslets method. An input flagellum dynamics parameter space is explored and corresponding bacterium reorientations tracked. The flagellum dynamics were modeled using three angles: (1) a polar angle, (2) the spinning of the flagellum about its axis, and (3) the twirling angle of the flagellum about the cell body longitudinal axis. The polar angle was determined via video footage from Xie et al.. The flagellum spinning rate was found to be 830 rotations per second to match the observed 36 micrometers per second swimming velocity. Both the spinning and twirling flagellum motions were required to achieve observed 90 degree reorientations and resulted in a twirling rate of 38.9 rotations per second. This allowed the cell body to increase its reorientation angle even when the flagellum returned to the swimming position. From an inertial perspective, this twirling rate produced 0.5 twirling rotations per flagellum decay, and ranged from 0.21 to 0.47 rotations depending on the flagellum polar angle, which was consistent with observations made from video footage. The second project aims to increase intuitive understanding of low Reynolds number dynamics by creating an interactive force-feedback simulator. Different scenarios were developed to focus the user on different aspects of swimming while encouraging critical thinking and group discussion. The simulator was simple enough to understand for younger age groups while the scenarios kept older age groups interested at education events like Engineer's Day and Summer Engineering Camps at the University of Nevada, Reno campus.