Numerical simulations of flapping foil and wing aerodynamics: Mesh deformation using radial basis functions

Both biological and engineering scientist have always been intrigued by the flight of insects and birds. For a long time, the aerodynamic mechanism behind flapping insect flight was a complete mystery. Recently, several experimental and numerical flow visualisations were performed to investigate the aerodynamics around flapping wings. Flapping wings produce both lifting and propulsive forces such that it becomes possible for insects and smaller bird species, e.g. hummingbirds, to stay aloft and hover, but also to perform extreme manoeuvres. Because of this versatility, insects and smaller birds are an inspiration for the development of flapping wing Micro Air Vehicles, small man-made flyer's to use in exploration and surveillance. In this thesis, Computational Fluid Dynamics methods are used to resolve the flow around two- and three-dimensional flapping foils and wings. Flapping wings, at the scale relevant to insect flight, move at large rotation angles, which is difficult to handle in existing mesh motion solvers. Therefore, existing methods to deform the mesh have been compared and improved. A relatively new method is implemented, based on the interpolation of radial basis functions. Using the mesh motion based on radial basis function interpolation, the flow around flapping airfoils and wings at hovering and forward flight conditions has been investigated. The forces and vortex patterns have been studied, especially the influence of wing kinematics on the leading-edge vortex. In addition, preliminary results are described of the effects by active wing flexing.