Experimental Investigations of Airborne Odor Plumes

We quantify the concentration distribution of airborne scalar plumes using planar laser-induced fluorescence. An ultraviolet laser excites fluorescence from an isokinetic release of acetone vapor (Sc≈1.5) in a benchtop-scale low-speed wind tunnel. Neutral buoyancy of the tracer gas is achieved by blending a mixture of helium and air, via mass flow controllers. We image the fluorescence at 15 Hz. Using this technique, we collect spatiotemporal concentration data with a detectability limit of 0.5% of the source concentration, and a field of view measuring 16 cm by 30 cm. We quantify plumes for several release configurations which exhibit different characteristics when comparing spatial distributions of instantaneous concentration, mean concentration, root-mean-square fluctuations, and concentration intermittency. The principal motivation is to further our understanding of the information available to terrestrial animals while navigating within odor plumes. The experiments provide novel data of airborne odor plumes that are then used in a range of related studies of animal olfactory navigation. We conclude by discussing approaches to advance these related studies.