New study solves mystery of how soft liquid droplets erode hard surfaces

The University of Minnesota Twin Cities led a study about why liquid droplets can erode hard surfaces. Engineers can use the discovery to design better erosion-resistant materials.

The researchers were able to measure hidden quantities such as the shear stress and pressure created by the impact of liquid droplets on surfaces, a phenomenon that has only ever been studied visually.

The paper was published in Nature Communications.

Researchers have been studying the impact of droplets for years, from the way they hit the ground to the way they spread diseases. Water droplets can erode surfaces over time. But why can something seem soft and fluid?

There are similar sayings in both eastern and western cultures, according to the senior author on the paper and an associate professor in the University of Minnesota Department of Chemical Engineering and Materials Science. Even if you are weak, you will make an impact when you keep doing something.

High-speed cameras have been used in the past to analyze droplet impact. The University of Minnesota has a new technique called high-speed stress microscopy that can be used to measure the force, stress, and pressure underneath liquid drops as they hit surfaces.

The researchers found that the force exerted by a droplet actually spreads out with the impacting drop instead of being concentrated in the center of the droplet and the speed at which the droplet spreads out exceeds the speed of sound at short times. The force necessary to erode surfaces over time is given by the impact energy of each droplet.

This research could help engineers design more erosion-resistant surfaces for applications that must weather the outdoor elements, as well as paving a new way to study droplet impact. Cheng and his lab at the University of Minnesota Twin Cities plan to expand their research to study how different materials affect the amount of force created by liquid droplets.

Cheng said that they paint the surface of a building or coat wind turbine blades to protect it. Our research after this paper is to see if we can reduce the amount of shear stress of droplets, which would allow us to design special surfaces that can mitigate the stress.

The research team included Cheng, a University of Minnesota chemical engineering student, and others.

More information: Stress distribution and surface shock wave of drop impact, Nature Communications (2022). DOI: 10.1038/s41467-022-29345-x Journal information: Nature Communications Citation: New study solves mystery of how soft liquid droplets erode hard surfaces (2022, March 31) retrieved 31 March 2022 from https://phys.org/news/2022-03-mystery-soft-liquid-droplets-erode.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.