Application of a Vortex Lattice Method to the Analysis of Sail Plans in Upwind Condition

To study new sail plans it is a common practice to use advanced CFD tools which are able to simulate in a accurate way almost all the aerodynamic complex phenomena typical of those systems. However, these analisys are very time consuming and this could make prohibitive their massive usage for long series of analysis. A way to solve this drawback could be found in Vortex Lattice Methods (VLM): with this technique it is possible to develop a lot of analysis, in a relative short time, in order to choose which will be the best configurations to test in detail. In the present article the results of analysis of sail plans, made with a in house software based on the VLM theory (Katz & Plotkin, 1991 and Fiddes & Gaydon, 1996) are shown. It is included an algorithm for wake relaxation. The validation of the method has been done comparing the results of the computation with those derived by the theory of elliptic wing and with available experimental tests at the wind tunnel on the sail rig of a modern racing yacht. Finally, the fluid dynamic code has been integrated with a non linear membrane FEM and an example of this application is presented.