Dissecting the aerodynamics of Morpho butterfly flight using various turbulence models

Morpho butterflies are among the largest flying insects, boasting a wing that can reach 20 centimetres in span. Such characteristic allows these butterflies to perform flying techniques that are common in birds but not in insects, like the gliding and flap-gliding flight style. During flap-gliding, Morpho butterlies fly at speeds of approximately 1.5ms-1, and thus the wings operate at Reynolds numbers of the order of 104. At this transitional Reynolds number regime, aerodynamic performance of a wing is notoriously difficult to estimate, as turbulence state is difficult to determine a priori (Spedding et al. [2008]). Here, we model the aerodynamics of gliding Morpho butterflies using different turbulence models with the aim at understanding which ones can give more realistic and reliable results.