Magnus regimes of a spinning Table Tennis ball: Insights into wake profile alteration

This study presents an experimental analysis examining the alterations in the pressure field induced by the transverse spinning of a table tennis ball within a wind tunnel setting. This work encapsulates the curved trajectory of the ball, particularly noticeable in around-the-net shots during intense table tennis rallies. Using a wake survey rake measurement system, a simultaneous traversal-imaging methodology was utilized in the retrieval of pressure values at a constant Reynolds number (Re) and varying spin ratios (Γ). Comparative analyses of spinning cases with a non-spinning case revealed notable alterations in the wake flow topology. At low to medium spin ratios, characterized as Magnus regime – I, a systematic lateral deflection of the wake was observed. This deflection varied as described in ϕ∝Γ1.2 toward the advancing side and was consistently attenuated. Upon transitioning into the inverse Magnus regime, the wake exhibited a notable contraction and reorientation along the central plane. At elevated spin ratios, denoted as Magnus regime – II, the initial deflection tendency was reestablished; however, it variably depended on the spin ratio as ϕ∝Γ6.1. The findings are consistent with established Magnus theories and offer significant insight into the various strategies for executing deceptive around-the-net shots in table tennis.