Effect of Dimple Topology and Ball Mass on the Aerodynamic and Flight Performance of Golf Balls

The flight performance of a golf ball is governed by its surface geometry, which controls boundary-layer transition, separation and wake formation, yet the effects of convex surface topology and of ball mass remain underexplored. This study experimentally compares three surface patterns of identical diameter and feature count: conventional circular dimples (baseline), hexagonal dimples and circular convex protrusions. Wake fields were characterised in a closed-loop water tunnel by Particle Image Velocimetry (PIV) and dye visualisation at Re = 1.5×10³ - 6.7×10³, and drag and lift were measured in a wind tunnel at Re = 2.9×10⁴ - 1.12×10⁵ with a combined uncertainty analysis. Over Re = 5.8×10⁴–1.1×10⁵ the baseline has the lowest drag at every test point, the convex and hexagonal patterns exceeding it by 5.8 ± 0.9 % and 5.1 ± 1.0 % on average, while the convex ball shows a pronounced negative-lift regime at intermediate Re. The measured CD(Re) and CL(Re) were applied to a two-dimensional, no-spin trajectory model with Monte Carlo uncertainty propagation at the regulation mass (45.93 g) and at 190 g. At regulation mass the ball decelerates into the negative-lift regime of the convex pattern, and the baseline carries 3.6 - 6.0 m farther than the convex ball for launch angles of 15.7° - 46.8°; at 190 g the ball remains above this regime and the two patterns become indistinguishable at a shallow launch angle. This Reynolds-number-mediated pattern–mass coupling provides a fluid-mechanical rationale for the dominance of circular dimples on regulation balls.