Aerodynamic performance of a bristled wing of a very small insect Dynamically scaled model experiments and computational fluid dynamics simulations using a revolving wing model

Aerodynamic force generation capacity of the wing of a miniature beetleParatuposa placentisis evaluated using a combined experimental and numerical approach. The wing has a peculiar shape reminiscent of a bird feather, often found in the smallest insects. Aerodynamic force coefficients are determined from a dynamically scaled force measurement experiment with rotating bristled and membrane wing models in a glycerin tank. Subsequently, they are used as numerical validation data for computational fluid dynamics simulations using an adaptive Navier-Stokes solver. The latter provides access to important flow properties such as leakiness and permeability. It is found that, in the considered biologically relevant regimes, the bristled wing functions as a less than 50% leaky paddle, and it produces between 66 and 96% of the aerodynamic drag force of an equivalent membrane wing. The discrepancy increases with increasing Reynolds number. It is shown that about half of the aerodynamic normal force exerted on a bristled wing is due to viscous shear stress. The paddling effectiveness factor is proposed as a measure of aerodynamic efficiency. [GRAPHICS] .