Volumetric flow field analysis of freely swimming lamprey using SAPIV

Volumetric, time-resolved flow field analysis of freely swimming lamprey Petromyzon marinus will be presented from Synthetic Aperture Particle Image Velocimetry (SAPIV) experiments. 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. Lamprey are a model biological organism for understanding locomotion control in vertebrates, thus inspiring this hydrodynamic investigation. The wakes considered herein are unconstrained in a quiescent tank, more than 15 body diameters deep, with a flat glass bottom; both forward swimming behaviors, as well as attempted burrowing behaviors, are observed. Kinematic body trajectory data and SAPIV results will be presented for several lamprey swimming cases. In general, lamprey swim by transferring momentum downstream via a traveling body wave to propel themselves forward, creating a thrust-like wake with downstream momentum flux. While 2D experiments with anguilliform swimmers have shown predominately lateral jets and a lack of downstream momentum flux, 3D SAPIV results show clear horizontal flows in the direction of fish swimming as well as lateral jets and flow around the top and bottom of body.