Rough surfaces can reduce friction drag

Research has revealed that a properly designed rough surface can reduce skin-friction drag.

John Kim and his colleagues have modeled the fluid flow between two surfaces covered with tiny ridges and found that even in turbulent conditions the rough surface reduced the drag created by the friction of flowing water.

The irregular fluctuations and swirling vortices in turbulent flows on smooth surfaces generally increase drag, but the superhydrophobic ridges altered the turbulent patterns near the surface, reducing their effect.

The researchers report their findings in the journal Physics of Fluids.