Methods of Restoring and Maintaining Gas Film on Superhydrophobic Surfaces while Underwater

Summary

UCLA researchers in the Department of Mechanical and Aerospace Engineering have developed a method of maintaining and restoring a gas film on a superhydrophobic surface while underwater.

Background

A liquid interfaced directly with a solid creates frictional forces. For example, these frictional forces slow down a boat traveling through the water and require it to use more power and fuel. A gas film layer between the solid and liquid interfaces would act to reduce frictional forces because the frictional drag of a liquid flowing over a gas film is lower than that of a liquid flowing directly over a solid.

Despite its usefulness, such a gas film layer is thermodynamically unstable. The gas film destabilizes from many different factors, including high liquid pressure, gas diffusion into the liquid, or physical defects on the surface - all of which are inevitable in most real life applications. Past research in the field focused on how to make the superhydrophobic surfaces more robust to prevent the gas film from destabilizing. None were directed at restoring and maintaining the gas film once it is disturbed.

Innovation

Researchers at UCLA have identified methods to re-establish a gas film on a structured hydrophobic surface underwater when the gas film is disrupted or depleted. The new methods immediately restore the gas film when a breakdown begins, thereby ensuring that a gas film is sustained for a sufficiently long time under various harsh conditions.

Applications

• Water craft manufacturing
• Water sports including surfing, wind sailing, water skis, etc.
• Any physical device that functions in water

Advantages

• Reduction of frictional drag under laminar and turbulent flow conditions
• Lower fuel costs
• Increase speed
• Prevent solid surface damage

State Of Development

The current methods have been demonstrated and experimentally verified using superhydrophobic surfaces.

Patent Status