Multifidelity approach to the numerical aeroelastic simulation of flexible membrane wings

Due to their lightness, the capacity to adapt to the flow conditions, and the safety when operating near humans, the use of membrane-resistant structures has increased in fields as micro aerial vehicles and yachts sails. This work focuses on the computational methodology required for simulating the aeroelastic coupling of the structure with the incident wind flow. A semi-monocoque structure (composed of a main spar, a set of ribs, and an external membrane) inside a wind tunnel is simulated using two different methodologies. Firstly, a complete fluid-structure interaction is calculated by combining the finite element methodology for the solid and the unsteady Reynolds average Navier-Stokes computational fluid dynamics for the air, including nonlinear effects and prestress. Then, a low-fidelity model is applied, obtaining the linear aeroelastic eigenvalues and the temporal response of the wing. Both methodologies results are in agreement with estimating the transient mean deformation and flutter velocity. However, the modal analysis tends to overestimate the aeroelastic effects, as it calculates potential aerodynamics, predicting an instability velocity lower than that provided by the transient simulations.