Research Stories

by Joe Kullman

Golf and high technology are being wedded ever more intensely. Vests imbedded with biosensors are strapped to golfers' bodies to monitor their every motion in the effort to improve swings. Lasers and radar and infrared cameras are used to dissect every conceivable aspect of equipment performance and players' proclivities.

But few technological forays into the quest for mastery of the game likely involve more intricate science than a project being led by two Arizona State University engineers.

The work combines aerospace engineering, supercomputing, and the latest in three-dimensional computer imaging. The ASU researchers are attempting to devise models for designs of the ultimate in flight-efficient golf balls.

Modeling of air flow around a golf ball

Kyle Squires is a professor of mechanical and aerospace engineering at ASU's Ira A. Fulton School of Engineering. Daniel Stanzione is an assistant professor who directs the university's High Performance Computing Institute. They study jet aircraft design and flight capability.

Srixon is an international sports equipment company. Executives at the company paid attention to those studies.

The company asked Squires and Stanzione if they could apply their combination of aerodynamic analysis and computational firepower to the relationship between golf ball design and performance.

The researchers answered yes, knowing that in some ways it would present more challenges than previous experiments.

"The precise modeling of air flow around a golf ball is in some ways more difficult than predicting air flow around a high-speed jet fighter undergoing extreme maneuvers," Squires says.

"In some flight regimes of a jet, the air flow close to the aircraft is actually less complex that what occurs in and around the dimples of a golf ball," he continues. "Much of the flight regime of a golf ball is among the least understood and most challenging to model."

What a standard golf ball does when hit is determined in large part by the dimples on its surface. The ball will act differently depending on the number, size, depth, width, shape and configuration of the dimples.

Finding out how different sets of those variables will affect a ball's behavior demands rigorous feats of mathematical modeling and computing.

"You can't just tell computers, ‘Start by thinking of a golf ball or a pencil.' It has no idea what a golf ball or a pencil is," Stanzione explains. "You have to give a computer the dimensions of the object. You have to provide it very specific geometry. Otherwise, you don_t get an accurate picture of whatever you_re trying to measure."

Such meticulous computations are essential to a comprehensive grasp of the various physical interactions that take place between a ball in flight and its environment, Squires says.

Turbulence is one of the most important phenomena that can influence the flight of a golf ball. Flight behavior is a reaction to turbulence that controls the forces on the ball. It determines the distance the ball will travel. So a key ingredient in achieving greater distance or accuracy is to control the characteristics of that turbulence through the surface design of the ball.

That means being able to see exactly how air is flowing around a ball. The engineers want to know how even the tiniest eddies of air are moving into and out of individual dimples.

Here's where ASU's Decision Theater is critical to the project. The facility is packed with state-of-the-art computerized imaging capabilities. The tools allow researchers to produce a revealing three-dimensional picture of moving objects, complete with slow-motion, stop-action and magnification.

The visual display the theater's technology can produce allows Squires and Stanzione to get an over, under, and inside-out simulation of turbulence in action around a ball in flight.

They can look at the air flow as if a ball is coming straight at them, going away from them, ascending, descending, or moving at varying rates of rotation.

Such versatile simulation capability boosts researchers' confidence about what can be achieved with their methods.

"Eventually, we'd like to use simulations to design a ball that would exhibit different flight characteristics," Squires says. "For example, golf balls that provide greater control over distance, or balls that won't tend to hook or slice as much."

"You could conceivably design a ball to match certain golfers' individual styles of play. There could be surface designs that would make a ball go farther or fly straighter under various climate conditions, like heat or humidity, or in cold, windy weather, or at high or low altitudes," he says.

The ASU researchers demonstrated their project's progress earlier this year. The demonstration lured representatives from several major sports technology and equipment makers and marketers.

It prompted inquiries about Squires and Stanzione broadening their studies to include computation of air flow around golf clubs. To devise equations for new models for more aerodynamically efficient club designs would mean factoring in disparate styles of golfers' swings. That would require researchers to introduce biomechanics into the scope of the studies. But expanding the work intrigues the engineers.

To date, most research into golf ball flight has involved measuring the "flow field," explains Alexander Smits, a professor at Princeton University. Smits was a consultant on ball aerodynamics for the United States Golf Association for more than a decade. He helped design and build the USGA's first indoor test range.

He's impressed that Squires and Stanzione are attempting the difficult task of going beyond measurement to prediction of the flow field. He says that such an advance could have a broad impact on aerodynamic research.

"There's a lot you could do with these kinds of findings," Stanzione says. "We can compute equations for just about anything that moves through the air -- whether it is trains, planes and automobiles, or golf balls. There is also sophisticated fluid dynamic modeling we could develop that would have all kinds of practical and commercial applications," he adds.

Sports equipment manufacturers could develop and test equipment designs completely in a virtual realm. They could eliminate the expense of building costly physical prototypes as well as repetitive and expensive testing procedures.

The methods could be adapted to development of new designs for aircraft, automobiles, and other types of vehicles.

"Sports equipment engineering relates to a lot of other areas," Squires says. "The numerical modeling we're applying raises fundamental research questions, which we also are investigating.

"Ultimately, we want to push this technology to the point where it could be used to test complete systems, whether it's a golf ball or an aircraft. The work could be done at a fraction of the substantial costs required today because of the need to build actual models," he says. "We just have to be able to demonstrate that our virtual-reality models accurately depict what would happen in the real world."

The ardent pursuit of better golfing appears poised to lead to technological innovations that reach far beyond the game.