Numerical study of two-dimensional heaving airfoils in ground effect

In this study, a potential-flow-based discrete vortex method is used to investigate heaving airfoils for a wing in ground effect (WIG) over a rigid surface and over progressive water waves. Three types of oscillations are analyzed, including forced harmonic oscillations over a rigid surface, harmonic oscillations over water waves and self-excited oscillations over water waves. In addition, the roll-up of the shed wake vortices is considered. Numerical results for unsteady airfoils with the three types of oscillations over a rigid surface and over incident water waves are presented. Satisfactory agreement with numerical results reported in the literature is documented. Interestingly, the phenomenon of water bump can be observed.