The vortex lattice grid method presented here is used to calculate aerodynamic forces generated by a sail set. The method assumes inviscid, incompressible steady-state flow and is not able to predict viscous forces, turbulence and flow separation (stall conditions). It is widely used to calculate flow forces for upwind sails in medium to strong wind conditions, where flow separation can be neglected and lift and induced drag dominates the flow forces.
The program, which is deployed here via download uses readily modelled sails, saved using the .ply-file format. Many CAD programs and surface modellers allow to export .ply-files. The examples shown here are generated using the Rhinoceros 3D (C) software.
Download: the download includes the binaries, a set of example files, a short manual and a theory skript. The software has been used since many years, but it is provided without any guarantee of accuracy, robustness or reliability.