In the present paper, a numerical model to study the nonlinear and unsteady aerodynamics of morphing-wing concepts inspired by bird flight is developed. The model includes: i) a wing topology inspired by gull wings; ii) a kinematical model to describe the process of wing adaptation based on one mechanism observed in the flight of gulls (folding-wing approach); and iii) a version of the unsteady vortex-lattice methods (UVLM) that allows taking nonlinear and unsteady aerodynamic phenomena into account. The model was specially developed to study the aerodynamic behavior during wing adaptation. A simulation for a twisting-flapping wing was performed in order to validate the numerical model. The present results are in close agreement with those obtained in previous studies based on the Euler equations, but required much less execution time. The numerical simulations of a bioinspired morphing wing showed the strong dependence between the prescribed kinematics and the aerodynamic characteristics, which evidences the importance of studying the process of wing adaptation. UVLM is shown to be ideal for preliminary analysis of bioinspired morphing wings.

In this work, the authors present a two-dimensional computational model for predicting the aeroelastic response as well as the output power of vertically arranged harvesters by taking into account all aerodynamic interactions. The piezo-aeroelastic framework consists of the following: (1) an aerodynamic model based on the unsteady vortex-lattice method to compute the aerodynamic forces; (2) a discrete parameter model for each harvester with 3 degrees of freedom (plunge motion, pitch motion, and the voltage generated by the piezoelectric effect); (3) an inter-model connection to exchange information between models at each time step; and (4) a numerical scheme based on the Hamming’s fourth-order predictor–corrector method to integrate all the governing equations in the time domain. The results obtained allow us to infer new insights into the flutter onset as well as the post-critical behavior of harvester arrangements. An interesting finding is that the flutter speed is significantly decreased as the distance between the harvesters is reduced. The results suggest the strong possibility of effective energy extraction at low flow speeds using properly distributed harvester arrangements. However, in post-critical conditions, the output power is significantly enhanced as the free-stream speed is increased.

Converting flow-induced vibrations into electricity for low-power generation has received growing attention over the past few years. Aeroelastic phenomena, good candidates to yield high energy performance in renewable wind energy harvesting (EH) systems, can play a pivotal role in providing sufficient power for extended operation with little or no battery replacement. In this paper, a numerical model and a co-simulation approach have been developed to study a new EH device for power generation. We investigate the problem focusing on a weakly aerodynamically coupled flutter-based EH system. It consists of two flexible wings anchored by cantilevered beams with attached piezoelectric layers, undergoing nonlinear coupled bending–torsion limit cycle oscillations. Besides the development of individual EH devices, further issues are posed when considering multiple objects for realizing a network of devices and magnifying the extracted power due to nonlinear synergies and constructive interferences. This work investigates the effect of various external conditions and physical parameters on the performance of the piezoaeroelastic array of devices. From the viewpoint of applications, we are most concerned about whether an EH can generate sufficient power under a variable excitation. The results of this study can be used for the design and integration of low-energy wind generation technologies into buildings, bridges, and built-in sensor networks in aircraft structures.