Numerical Simulations of the Effect of the Asymmetrical Bending of the Hindwings of a Hovering C. buqueti Bamboo Weevil with Respect to the Aerodynamic Characteristics

Abstract

The airfoil structure and folding pattern of the hindwings of a beetle provide new transformation paths for improvements in the aerodynamic performance and structural optimization of flapping-wing flying robots. However, the explanation for the aerodynamic mechanism of the asymmetrical bending of a real beetle’s hindwings under aerodynamic loads originating from the ventral and dorsal sides is unclear. To address this gap in our understanding, a computational investigation into the aerodynamic characteristics of the flight ability of C. buqueti and the large folding ratio of their hindwings when hovering is carried out in this article. A three-dimensional (3D) pressure-based SST k-ω turbulence model with a biomimetic structure was used for the detailed analysis, and a refined polyhedral mesh was used for the simulations. The results show that the fluid around the hindwings forms a vortex ring consisting of a leading-edge vortex (LEV), wing-tip vortex (TV) and trailing-edge vortex (TEV). Approximately 61% of the total lift is generated during the downstroke, which may be closely related to the asymmetric bending of the hindwings when they are subjected to pressure load.

Structural response and mechanical properties of the hind wing of the beetle Protaetia brevitarsis

“…Based on the Reynolds number calculation method of insect flight (Aono et al, 2008; Li, 2022), the flow characteristics of the surrounding fluid caused by the flapping of the hind wing in the computational domain is modeled as turbulent incompressible air under standard atmospheric conditions. CFD simulation analysis was carried out using a three dimensional pressure based SST k‐ω turbulence model.…”

“…The vertical force generated during the downstroke exceeds 50% of the total lift. The C L is a typical method used to represent vertical forces (Aono et al, 2008; Li, 2022), where the projected area was measured by UG NX. The average vertical force of a single hind wing in one stroke cycle is calculated to be 0.0088 N, which provides first‐hand data for analyzing the structural response characteristics of the hind wing by applying pressure and tensile loads on the wing surface.…”

“…The data file of the reverse reconstructed model from the 3D scanning were written into NX 12.0 to develop a constant thickness model (Li, 2022), the computational domain was modeled as a rectangular box with a length, width, and height of 220, 110, and 80 mm, respectively. The CFD simulation analysis of insect flapping behavior follows the setting benchmark of this size in the computational domain, which is far enough in the far-field and downstream boundaries to not affect the flow behavior near the hind wings (Aono et al, 2008).…”

“…The commercial CFD software package (Fluent) based on the dynamic mesh method was chosen as the fluid solver. At the initial time, both the hind wing model and the entire flow field were considered as stationary.Based on the Reynolds number calculation method of insect flight(Aono et al, 2008;Li, 2022), the flow characteristics of the surrounding fluid caused by the flapping of the hind wing in the computational domain is modeled as turbulent incompressible air under standard atmospheric conditions. CFD simulation analysis was carried out using a three dimensional pressure based SST k-ω turbulence model.…”