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Study finds rough surfaces may eliminate drag, reduce global warming

It’s a major discovery that could redefine how everything from yacht hulls to swimming suits are designed.

According to researchers at UCLA, rough surfaces lined with tiny ridges may actually reduce drag. Modeling fluid flow between two surfaces lined with tiny ridges, researchers found tiny ridges actually reduce drag, allowing the for fluid to flow around in a more efficient manner.

“A properly designed rough surface, contrary to our intuition, can reduce skin-friction drag,” said John Kim, a professor in the mechanical and aerospace engineering department at UCLA.

The team of researchers say the discovery is likely to be applied to seafaring vessels rather than objects directly impacted by air flow.

This is not the first time scientists have sought to create models based on rough ridges to reduce drag. However, advances in technology now allow scientists to create models on a microscopic level. Relying on superhydrophobicity, scientists were able to create ridges that trap air bubbles, creating a natural barrier between liquids and the surface of the object. Researchers modeled both laminar and turbulent flows, and unexpectedly found that the drag-reduction was larger in turbulent conditions.

The team says the finding could eventually lead to more efficient cargo vessels and shipping containers. The increase efficiency may allow for steep declines in fuel usage, a change that would have a substantial impact on global warming emissions, say scientists. Shipping is responsible for four percent of the U.S.’s total greenhouse gas emissions and globally the sector represents percent of greenhouse gas emissions.

The discovery is published in the latest issue of the journal Physics of Fluids.