The Dimpled Future of Cars

Avid golfers will tell you that their golf balls have dimples to improve aerodynamic performance. It is now being touted around scientific circles that this aerodynamic miracle that is the golf ball could give a fuel economy boost to cars of the future.

But hang-on. Wasn't there an episode of Mythbusters with Jamie and Adam on Discovery Channel that debunked the theory of efficiency gains of a dimpled car? So it must be a myth, even though the pattern of indentations reduces drag on a golf ball. 

Now, reports coming out of the famed Massachusetts Institute of Technology(MiT) and reported in Science Daily would have us believe that shape-shifting golf ball-inspired material could be the answer to improving car efficiency and bringing down drag. Well, at least if we are to believe the author, David Chandler.

Apparently the problem is that the effect the dimples have on the aerodynamic properties changes depending on the speed of the vehicle and thus it transpires that the Mythbusters were only partially correct. Aerodynamic experts at MiT claim to have developed a surface that can morph from smooth to dimpled at the touch of a button. The scientists said applying it to various panels on a car would minimise drag at different speeds and increase fuel efficiency.

The dimpled principle is nothing new, with golf balls having used a indented face to travel further since the 19th century and footballs in the 2014 World Cup also feature a textured surface. In short, a dimpled surface works by holding the airflow closer for longer, reducing the turbulent air behind the ball which is the primary cause of drag on blunt objects.

The reason that it has never been used in the car industry before now is quite simple, as the Mythbusters discovered, is that whilst it may suit urban driving at lower speeds, at higher speeds - such as on motorways or dual carriageways - the efficiency advantages are reversed. Therefore if you can turn the effect off and on, as it is needed, then it can become beneficial. The new smart morphable surface or smorph, as it is being called by those trendy little rascals over at MiT, is a major breakthrough and according to them could reap many real-world mpg benefits.

The new smorph material features a stiff outer skin covering a soft interior (sounds like chocolates); when the pressure of the inside is lowered, the outer skin shrinks, creating a dimpled surface. This is the same principle that sees fruit wrinkle as it gets old.

Pedro Reis, an Assistant Professor of Mechanical Engineering and Civil & Environmental Engineering at MiT, said, “That reversibility is why it’s interesting; you can switch the drag-reducing effect on and off, and tune it.” Pedro, maybe you need to get out more.

image: discovery.com