Wing-wing interactions at low Reynolds numbers: a computational investigation of hovering flight in the tobacco whitefly

The tobacco whitefly (Bemisia tabaci) is a tiny four-winged insect that flies with a Reynolds number of approximately 10. Unlike many other insects of similar size, the whitefly does not possess bristled wings; rather, it flies using two sets of membranous forewings and hindwings. At such low Reynolds numbers, it is suspected that wing-wing interactions like clap-and-fling play a critical role in lift generation. However, it remains unclear exactly how such mechanisms contribute to aerodynamic performance, particularly in four-winged insects like the whitefly. In this work, we examine these wing-wing interactions using computational fluid dynamics (CFD) simulations of tobacco whitefly flight. We begin by creating a three-dimensional kinematic reconstruction based on a high-speed video of a hovering whitefly. We then simulate the reconstructed model using an in-house immersed-boundary-method CFD solver. In addition to the original flight case, we evaluate several artificial wing configurations to quantify the role of unilateral wing interactions (forewing-hindwing) and bilateral interactions (clap-and-fling). Force production and wake isosurfaces are compared across simulation cases to better understand the aerodynamic mechanisms leveraged by insects such as the whitefly. Our results suggest that bilateral clap-and-fling-type interactions boost lift generation by ~10%, while unilateral interactions between forewing and hindwing have negligible effect. These findings contribute to our understanding of low Reynolds number flapping flight, providing potential inspiration for the design of bio-inspired micro-aerial vehicles.