Vortex flow of yacht sails

The flow around America’s Cup yacht sails are studied to investigate the role of vortex flow on performances. Computational fluid dynamics simulations and experimental measurements on scaled models are performed. Detached Eddy Simulations of an asymmetric spinnaker at Reynolds number 6 x 105 (Viola et al., 2014, OE, 90:93-103) suggested that the flow separates at the leading edge followed by turbulent reattachment, forming a leading edge vortex (LEV). This was recently confirmed by Particle Image Velocimetry at a Reynolds number of 1.7 x 104 (Arredondo and Viola, UK Fluids 2016). It was found that the LEV is stably attached to the leading edge and its diameter grows from the foot to the tip of the sail. On the lower half of the sail, the LEV has a negligible diameter while large trailing edge separation occurs. Conversely, on the highest sections, the diameter of the LEV is more than a quarter of the chord and trailing edge separation does not occur. The industrial exploitation of these results is enabled by the development of a low-order model (based on potential flow) which will underpin future design tools. This work is the first experimental evidence of the existence of a stable LEV on yacht sails.

The project is co-funded by CONACYT.