Effects of Dimple Size and Depth on Golf Ball Aerodynamic Performance

Abstract

Based on the three-dimensional CFD modeling method reported previously, systematic computational sensitivity studies of how the changes of dimple size, depth, number, coverage area, and distribution pattern will affect the golf ball aerodynamic performance have been made by considering those variables individually and then collectively. By using a new golf ball surface design with 344 identical single-sized circular dimples, but keeping the dimple distribution pattern and the dimple diameter unchanged, the dimple depth effect was first investigated by varying the dimple depressions from shallow to deep, and an optimum value corresponding to minimum drag loss has been found. Using the balls with same optimum dimple depth, drag results show the tendency of decreasing as the dimple diameter increases from small to large until a limit is reached. Beyond this limit, drag coefficient will remain to be a constant even with the further increases of the dimple diameter. Ball drag and lift results obtained and presented are not only for the whole ball, but also separately for the dimple occupied area and the dimple-free cage area. Influence of ball backspin motion to the magnitude of the dimple’s optimum depth value was found to be insignificant. Flow field solutions of velocity vectors, trace lines, pressure, and turbulence intensity have also been obtained, and some are used to show how the changes of dimple depth, dimple diameter, as well as the ball backspin motion, will affect the wake formation behind the ball both in size and shape.