Deformable model of a butterfly in motion on the example of Attacus atlas.

Abstract

Insect wings can undergo significant chordwise (camber) as well as spanwise (twist) deformation during flapping flight but the effect of these deformations is not well understood. The shape and size of butterfly wings leads to particularly large wing deformations, making them an ideal test case for investigation of these effects. High-speed videogrammetry was used to capture the wing kinematics and deformations. The movements of selected markers on the wings of a living insect was observed. Created characteristics showing the displacement in a three-dimensional coordinate system identified the kinematics and deformations of the butterfly's wings. These experimental results were then analyzed computationally using a high-fidelity, three-dimensional, unsteady Navier-Stokes flow solver. Computational fluid dynamics (CFD) simulations were carried out on the basis of the wing geometry of the large moth Attacus atlas. Six geometric and structural models of the Attacus atlas butterfly wing with various degrees of simplification were developed. Using these models, Fluid-Structure-Interaction (FSI) simulation studies were performed in the commercial Ansys software environment (Fluent and Mechanical). Computations of the wing beat cycle were carried out, obtaining pressure distributions, streamlines, vortex regions and cumulative force waveforms.