EFFECT OF FLIGHT SPEED ON AERODYNAMIC PERFORMANCE, VORTEX STRUCTURES, AND ODOR INTENSITY IN BLUE BOTTLE FLIES

Odor-guided navigation constitutes a fundamental survival strategy for many flying insects, enabling them to locate food sources, identify mates, and avoid predators. Among these insects, flies are particularly reliant on their olfactory systems to detect airborne chemical cues essential to their ecological behavior. The aerodynamics of flight governed by parameters such as speed, wing kinematics, and maneuverability not only influence kinematics but also modulate the airflow and odorant transport around the insect's sensory organs. Despite extensive studies on insect flight mechanics and odor tracking behavior, the integrated effects of flight speed on aerodynamic performance and olfactory perception remain insufficiently explored. This study investigates the interplay between flight speed and odor-guided navigation in the blue bottle fly (Calliphora vomitoria), a species renowned for its agile flight and enhanced olfactory perception. Using high-fidelity computational fluid dynamics (CFD) simulations with an in-house immersed-boundary-method-based solver, we simulate forward flight across a range of speeds (0.58 m/s to 1.25 m/s). The wing kinematics used in the simulations are reconstructed from high-speed videos to capture the realistic blue bottle fly’s flight. This enables us to assess the effects of flight speed on aerodynamic performance, vortex dynamics, and the temporal distribution of odor concentrations near the antennae. Our findings reveal that flight speed significantly influences odor sensitivity. At lower speeds, odor concentration near the antennae increases, enhancing olfactory sensitivity. However, this comes at the cost of reduced temporal variation in odor signals, potentially decreasing odor tracking efficiency. Aerodynamically, slower flights produce weaker leading-edge vortices and altered wake structures, which may decrease lift generation and flight stability. Additionally, speed dependent variations in the wingbeat kinematics affect the entrainment and advection of odor plumes toward the sensory organs, illustrating a complex coupling between biomechanical and sensory processes. These results suggest a trade-off between olfactory sensitivity and signal consistency as a function of flight speed. The study provides new insights into how flies modulate their kinematics to optimize olfactory sensitivity in complex flow environments. In addition to deepening our understanding of insect sensory mechanisms, this research provides valuable design insights for the development of bio-inspired aerial robotics. Mimicking the Speed-modulated odor detection strategies observed in flies may enable the development of autonomous systems with enhanced environmental sensing capabilities for applications such as search-and-rescue missions and environmental monitoring.