Electrostatics influence the movement of drops on surfaces

One would think that the motion of water on the surface should be understood. There are many unanswered questions about the forces acting on a sliding droplet. A team of researchers from the Max Planck Institute for Polymer Research in collaboration with colleagues from TU Darmstadt have discovered that electrostatics play a significant role in droplets. The results were published in a journal.

The wind pushes the raindrops to the side of the car window. No one has been able to predict how the drops will move. An understanding of this is important in many areas, such as self-driving cars, where cameras are supposed to keep an eye on the road and traffic situation. The opposite sign is used for applications where drops need to stick to the surface.

It was assumed that the surface coating was responsible for how droplets move on a surface. It depends on the surface whether a spherical or flat shape is formed. If the drop likes the surface, it presses itself flat onto it to make contact. In the case of the lotus effect, if it doesn't like the surface, it curls up. It was clear that when a droplet moves, the individual water molecule's movement is influenced by the other variables.

There are differences in velocity caused by sedans.

The team of researchers at the MPI found that capillary and viscoelastic forces can't explain the differences in the speed at which droplets move across different surfaces. Questions were raised about the fact that the droplets run at different speeds on different surfaces, even if they have the same surface coating. Xiaomei Li organized a drop race to find the mysterious extra force that was introduced by the researchers.

The results show that the force agrees with the force described in the model a few years ago. A group leader in Butt's department.

If neutral droplets slide over an insulator, they can become charged. The droplet immediately releases its charge back to the substrate if it is on an electrical surface. The results of the research have been published. The results will improve the control of droplet motion in many applications.

More information: Xiaomei Li et al, Spontaneous charging affects the motion of sliding drops, Nature Physics (2022). DOI: 10.1038/s41567-022-01563-6 Journal information: Nature Physics Citation: Electrostatics influence the movement of drops on surfaces (2022, April 15) retrieved 15 April 2022 from https://phys.org/news/2022-04-electrostatics-movement-surfaces.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.