I2M, Aix-Marseille University, France
Date(s) : 15/04/2020 iCal
14 h 00 min - 15 h 00 min
The secret to the spectacular flight capabilities of flapping insects lies in their wings, which are often approximated as flat, rigid plates. Real wings are however delicate structures, composed of veins and membranes, and can undergo significant deformation. In this talk, we present detailed numerical simulations of such deformable wings. Two models of a bumblebee (Bombus ignitus) wing and a blowfly (Calliphora vicina) wing, using a mass-spring system, are presented. The mass-spring model uses a functional approach, thus modeling the different mechanical behaviors of the veins and the membranes of the wing. Then, numerical simulations of tethered flapping insects with the flexible wings are obtained with a fluid-structure interaction solver, coupling a mass–spring model for the flexible wing with a pseudo-spectral code solving the incompressible Navier–Stokes equations. We impose the no-slip boundary condition through the volume penalization method; the time-dependent complex geometry is then completely described by a mask function. This allows solving the governing equations of the fluid on a regular Cartesian grid. Our implementation for massively parallel computers allows us to perform high resolution computations with up to 500 million grid points. The preliminary results obtained in this work allow us to have some understanding about the role of wing flexibility in flapping flight. We found that wing flexibility hardly contributed to lift or thrust enhancement. However, the significant reduction of the required power suggested that wing flexibility plays an important role in saving flight energetic cost.
Truong Hung, I2M, Aix-Marseille University, France