Two-dimensional immersed boundary simulations were performed to determine how stroke plane angle and wing flexibility affect aerodynamic efficiency and energy efficiency for the smallest flying insects (here boundary refers to the boundary of the elastic structure immersed in the fluid). Extensive experimental data pertaining to small insect flight is unavailable due to the difficulties associated with directly observing the flight of the smallest insects and therefore, their flight mechanisms are still largely unknown. The immersed boundary method was used to solve the fully coupled fluid-structure interaction problem of a flexible wing immersed in a two-dimensional viscous fluid. We considered five different strokes: a horizontal stroke, three different hybrid strokes, and a vertical stroke. We also considered five different wing flexibilities ranging from rigid to highly flexible. Aerodynamic efficiency was defined as the ratio of the average vertical force coefficient to the average total force coefficient and energy efficiency was defined as the ratio of the average vertical force generated by a wing to the average power delivered by the wing to the surrounding fluid. The results indicate that at Reynolds numbers (Re) relevant to small insect flight (4 – 60), both aerodynamic efficiency and energy efficiency decrease with increasing stroke plane angle regardless of wing flexibility.
At Re pertinent to small insect flight, a rigid wing is aerodynamically as well as energetically more efficient than flexible wings at all stroke plane angles. This suggests that a rigid wing with a horizontal stroke could be aerodynamically as well as energetically the most efficient wing flexibility and stroke plane angle combination in the flight of the smallest insects.
Keywords: Immersed Boundary Method, Computational Fluid Dynamics, Small Insect Flight
How to Cite:
Aghav, H. & Miller, L. A., (2022) “Two-Dimensional Aerodynamic Analysis of Flight in the Smallest Insects”, Arizona Journal of Interdisciplinary Studies 8, p.60-87.