| Summary: | Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2019 === Cataloged from PDF version of thesis. === Includes bibliographical references (pages 85-89). === An experimental procedure to study lamprey hydrodynamics using Synthetic Aperture Particle Image Velocimetry (SAPIV) was developed and applied in this thesis. Volumetric, time-resolved flow field analysis of freely swimming lamprey, Petromyzon marinus, are presented from SAPIV experiments. As the most primitive living vertebrate, this eel-shaped fish has served as a model organism for understanding locomotion control in vertebrates. Brain and spinal cord mappings of the lamprey nervous system are well characterized and share key features with neural systems across the animal kingdom. However, a comprehensive understanding of locomotion control strategies in lampreys hinges upon characterizing the external fluid environment they experience. Thus, its role as a model organism has motivated this hydrodynamic study. Lamprey are slender-bodied, anguilliform swimmers that move by sending a traveling wave of increasing amplitude from head to tail, around Reynolds number order 10⁵. Generally, lamprey swim by advecting momentum downstream via the traveling wave on the body, creating a thrust-like wake with downstream momentum flux. Previous investigation suggests that lamprey locomotion arises from complex 3D flow field interactions, although this has never been studied using a live fish. To investigate the degree to which 3D effects are meaningful in lamprey hydrodynamics, SAPIV was used to study their unconstrained swimming in a quiescent tank more than 15 body diameters deep. SAPIV velocity fields show that a bifurcated wake consisting of predominantly lateral jets is produced by lamprey. Downstream velocities are also observed although they are about one half the magnitude of lateral velocities. This measurement contribution moves towards an understanding of lamprey swimming behavior and builds upon the foundation for understanding the hydrodynamics of unsteady, flexible propulsors. === by Andrea Michelle Lehn. === S.M. === S.M. Massachusetts Institute of Technology, Department of Mechanical Engineering
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