The shape of a sail influences the airflow characteristics around it, and flexible sails are prone to large nonlinear deformation under wind pressure. As such, this paper studies the effects of sail deformation on aerodynamic performance.

A fluid-structure interaction (FSI) study on flexible sail deformation is performed. The initial shape model and material model of a sail are established, an explicit finite element method (FEM) such as AUTODYN is applied to calculate the large nonlinear deformation of the sail, and the shape of the deformed sail is constructed. STAR-CCM+ is applied to predict the performance of the initial and deformed sail.

The results show that positive pressure on the windward side of the deformed sail increased, and the flow separation generated around the leeside of the sail leech became more severe in upwind conditions with a relative wind angle of 20°. The increase of the lift force due to the rise of the camber was relatively small, resulting in a decrease in overall lift force.

FSI studies on flexible sail deformation are suitable for the precise evaluation or optimization of sail performance.