Computational analysis of the fluid–structure interactions of a synthetic badminton shuttlecock

Fluid–structure interactions of a synthetic badminton shuttlecock at various flight speeds are investigated computationally. The cork of the shuttlecock is held fixed and its skirt is free to deform. The cross-sectional area of the skirt decreases with an increase in flight speed leading to a significant reduction in the drag compared to that for an undeformed shuttlecock. Four regimes of deformation, with an increase in speed, are identified. The deformation is steady and axisymmetric in regime 1. Beyond a certain speed, which is referred to as “buckling speed,” the deformation is in regime 2. The skirt assumes a non-axisymmetric shape with a significant increase in its rate of deformation with speed. It undergoes vibration in regime 3. The amplitude of vibration increases with increased speed. In regime 4, the vibrations are modulated atop a lower frequency wave that travels circumferentially along the skirt. Compared to a rigid shuttlecock at the same flow speed, the streamwise vortex structures inside the skirt are weaker in a deformed shuttlecock. The decrease in the drag coefficient with an increase in speed is due to a decrease in the cross-sectional area of the skirt as well as a reduction in the entrainment of the flow through the gaps in the skirt area. The computational results are in good agreement with the available experimental measurements. The effect of the elastic modulus of the material and various structural reinforcements is studied.