A multidisciplinary computational framework for sailing yacht rig and sails design through viscous FSI

Abstract

Although competitive sailing yachts may sail fast today this is mainly due to material progress, not sail design. It is always difficult to design a set of sails for a given boat and sailing conditions. A sail has one design shape but an infinite number of corresponding flying shapes depending on materials, trimming, rigging and wind conditions. In this paper a computational framework for sail analysis, design and optimization has been extended to Fluid-Structure Interaction (FSI) and will be presented. The multi-physics computational framework is based on a viscous Computational Fluid Dynamics (CFD) solver for the fluid part and on a nonlinear structural modelling for the structural part. A loose coupling of both models has been implemented to be able to make Fluid-Structure Interaction simulations on various sail configurations and to investigate the relation between a design shape and its corresponding flying shapes. The computational framework presented also contains an optimization package based on derivative-free evolutionary strategies to address complex, non linear optimization problems. It will be used on few examples of sail design questions to illustrate how it may contribute to put some rational elements in a rather frequently passionate discussion between sailors, sail designers, naval architects and amateurs to design the right set of sails for a given boat.