Numerical study of a flexible sail plan: effect of pitching decomposition and adjustments

A numerical investigation of the dynamic Fluid Structure Interaction (FSI) of a yacht sail plan submitted to harmonic pitching is presented to analyse the effects of motion simplifications and rigging adjustments on aerodynamic  forces. It is shown that the dynamic behaviour of a sail plan subject to yacht motion clearly deviates from the quasi-steadytheory. Theaerodynamicforcespresentedasafunctionoftheinstantaneousapparentwindangleshow hysteresis loops. These hysteresis phenomena do not result from a simple phase shift between forces and motion. Plotting the hysteresis loops in the appropriate coordinate system enables the associated energy to be determined. This amount of exchanged energy is shown to increase almost linearly with the pitching reduced frequency and to increase almost quadratically with the pitching amplitude in the investigated ranges. The effect of reducing the real pitchingmotiontoasimplersurgemotionisinvestigated. Resultsshowsignificantdiscrepanciesontheaerodynamic forces amplitude and the hysteresis phenomenon between pitching and surge motion. However, the superposition assumption consisting in a decomposition of the surge into two translations normal and collinear to the apparent wind is verified. Then, simulations with different dock tunes and backstay loads highlight the importance of rig adjustments on the aerodynamic forces and the dynamic behaviour of a sail plan.

How to cite
Augier Benoit, Hauville Frédérick, Bot Patrick, Deparday Julien, Durand Mathieu (2013). Numerical study of a flexible sail plan: effect of pitching decomposition and adjustments. INNOV’SAIL 2013. Proceedings of the Third International Conference on Innovation for High Performance Sailing Yachts INNOV’SAIL. 26-28 juin 2013, Lorient, France. pp.155-164.

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