Vortex Lattice Method approach to sailing yacht foil design: feasibility and comparison with RANS method results

Abstract

The Reynolds-averaged Navier-Stokes (RANS) equations are the industry-standard computational fluid dynamics method for estimating forces, viscous effects, and boundary layer behaviour in various flow conditions, including adverse pressure gradients and flow-separation regimes. However, despite the ever-increasing availability of computational power, there are several scenarios in which more rapid methods, based on suitable simplified assumptions, offer advantages with respect to the RANS approach. Foil devices often operate at low angles of attack, high Reynolds numbers, and without fluid separation. These conditions make the Vortex Lattice Method (VLM) a viable and faster alternative for exploring the wide design space of yacht foils. In this study, the hydrodynamic forces generated by various foil geometries are computed using an original VLM formulation for generally curved lifting surfaces. The case study is focused on the foils of an ecofriendly dinghy designed and manufactured by students in the international framework of 1001VELAcup. The results are compared with those provided by RANS simulations, and the feasibility of the proposed approach for the design of yacht foils is discussed.