SRI supercomputer unravels mysteries of golf ball flight

ERJ staff report (DS)

San Antonio, Texas -- Sumitomo Rubber has worked with two US universities to calculate the detailed air flow around a golf ball in flight, using advanced numerical simulations. The project is a collaboration between Dr. E. Balaras from the University of Maryland, Dr. K. Squires from Arizona State University and Masaya Tsunoda of Sumitomo Rubber Industries, Ltd.

Their work was presented last week at the 61st Meeting of the American Physical Society's Division of Fluid Dynamics in San Antonio, Texas. Keen golfers should not hold their breath: products using the analysis are still years away, said SRI.

The team has used a supercomputer to model how air flows around a ball in flight and to study how this flow is influenced by the ball's dimples. Their goal is to make a better golf ball by optimising the size and pattern of these dimples and lowering the drag golf balls encounter as they fly through the air.

Up to now, dimple design has been more of an art than a science. For many years, sporting goods companies would design their dimple patterns by simple trial and error, testing prototype after prototype against one another. The new study takes a different approach, asking how to design dimple size and pattern based on mathematical equations that model the physics of a golf ball in flight. Working out the solution to these equations -- even on the fastest personal computers today -- is not feasible since it would take more than 15 years of computing time just to get a glimpse of the flow around the golf ball for a fraction of a second.

Nikolaos Beratlis, a Ph.D. student at the University of Maryland, and his advisor Elias Balaras have been developing highly efficient algorithms and software to solve these equations on parallel supercomputers, which can reduce the simulation time to the order of hours. The number crunching for a typical computation, for example, takes approximately 300 hours using 500 fast processors running in parallel (normal desktop computers may have one or two slower processors).

The group's work presented by Smith in San Antonio summarised their research. So far, they have characterised air flow around a golf ball at the finest level of detail ever attempted, teasing out the drag at each exact location and showing how air flows in an out of each tiny dimple on a golf ball's surface as it spins through the air during flight.

In the end, they produced a model that reveals the physics of a flying golf ball with the greatest level of detail ever seen -- the first step in achieving the project's long-term goal of optimising dimple design to realise the lowest drag possible. The next step, says Smith, is to extend the work by comparing different dimple designs.

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Press release from APS