Odor landscape dynamics in low-Reynolds number, low-Schmidt number plumes

Terrestrial olfaction occurs in relatively low-Re, low-Sc odor landscapes (plumes). Coupled flow and odor cues are particularly relevant for insects sampling these plumes during olfactory navigation, which is fundamental to predator-prey dynamics, mate location, habitat selection, and foraging. In this study, we experimentally measured the spatiotemporal evolution of both fluid velocity and odor concentration in low-Re, low-Sc plumes generated in fractal grid turbulence using stereo particle image velocimetry (sPIV) and planar laser-induced fluorescence (PLIF). Acetone vapor serves as an odor simulant and is released isokinetically 10 cm downstream of a square fractal grid. Fluorescence is excited by four ultra-violet pulsed lasers (266 nm, 90 mJ/pulse) and imaged at up to 40 Hz with 350 micron spatial resolution over a 30 cm FOV. A separate pulsed green laser (532 nm, 200 mJ/pulse) and two additional sCMOS cameras capture sPIV data over the same FOV with comparable vector resolution at up to 30 Hz. Here, we present turbulent velocity and scalar statistics measured separately in stationary plumes, while future work will combine this infrastructure to make simultaneous sPIV and PLIF measurements of odor landscapes in the low-Re, low-Sc regime relevant to olfactory navigation.