Flight and Smell: Exploring the Impact of Wing Structure and Kinematics on the Olfactory Function of Flies in Upwind Surging Flight*

One of the most ancient, conserved behaviors in animals is using wind-borne odor plumes to track food, mates, and predators. Insects, particularly flies, exhibit a high level of proficiency in this, processing complex odor information like concentrations, direction, and speed, through their olfactory system for effective odor-guided navigation. Extensive research has illuminated the influence of wing structure and kinematics on the aerodynamics and flow field physics of flying insects in recent years. However, the interplay between the flow field and olfactory functions remains uncharted territory, inviting intriguing questions. For instance, do flies intentionally manipulate the flow field around their antennae using their wing structure and kinematics to enhance their olfactory abilities? To investigate this, we conducted CFD simulations on blue bottle flies (C. vomitoria) forward flight by using an in-house immersed-boundary-method-based CFD solver. By using high-speed video recordings, we reconstruct the wing shape and kinematics of the fly. Results suggested that flies utilize their wing structure and kinematics to manipulate flow physics to increase odor concentrations around their antennae. Remarkably, the flapping motion enabled a significant enhancement in the odor-mass flux reaching to their olfactory receptors compared to the case without flapping motion.