107.2 Saturday, Jan. 7 Desert locust aerodynamics: instantaneous wake volumes using tomographic particle image velocimetry (tomo-PIV) BOMPHREY, R.J.*; HENNINGSSON, P.; MICHAELIS, D.; HORSTMANN, T.; HOLLIS, D.; University of Oxford firstname.lastname@example.org
Tomographic Particle Image Velocimetry (tomo-PIV) is becoming increasingly established in the experimental fluid mechanics community as a volumetric method for the analysis of complex flows, but has yet to be applied to animal flight despite the major advances in the field made possible by its planar predecessors. The technique captures a volume of instantaneous flow velocity vectors with equal resolution along each axis rather than the more limited experimental sampling plane of stereo-PIV. From the three-dimensional flow fields, a portrait of the flow features can be visualized and quantified. We recorded the wake of desert locusts flying tethered in a wind tunnel using broad sheet laser illumination operating at 1kHz (pulse pairs) and a four-camera data acquisition system. This resulted in overlapping, near-wake volumes forming a time-resolved representation of the vortex wake. Here we present novel, Tomo-PIV data revealing, for the first time, wake components of a flying animal that have been hitherto undetectable using existing techniques. The wake is complex, due primarily to the existence of out of plane vortex elements of variable strength and significant wake deformation is apparent. To compliment the tomo-PIV study, we have characterised some of the most important parameters concerning wake deformation relevant to animal flight using fixed-wing model flow visualization.