Computational modelling of fixed and rotary wing aerodynamics operating in close proximity to wavy free surfaces

The impact on the aerodynamics of a fixed wing, an unmanned aerial vehicle (UAV) and a rotary wing, due to the presence of a ground and wavy free surface of an air-sea interface in close proximity, is studied using computational methods in this work. The incompressible Reynolds Averaged Navier Stokes (RANS) equations are solved for the flow, while the air-sea interface is captured using the Volume of Fluid (VOF) technique. The motivation behind this work is to study the effect of wavy or calm surface of a water body or sea on fixed and rotary wing aerodynamics and compare the differences in the vicinity of a rigid ground surface, which is the approach normally taken to model ground effect in most of the existing computational studies. In order to study the perturbation of the free surface, this study uses a multi-phase approach to capture the free surface, rather than pre-defining it as a rigid boundary. Waves of different patterns are generated by using appropriate source terms in the momentum equation (by way of a numerical wave maker) and the effect of these on the fixed and rotary wing aerodynamic characteristics are analysed. The results observe a significant variation in aerodynamic quantities depending on the wave characteristics.