Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Mathematicians defy gravity

05.10.2007
Droplets of liquid have been shown to travel uphill, rather than sliding down as expected, when the surface they are on is vigorously shaken up and down.

We are all familiar with raindrops on our wind screens. The small ones stay in place while the big ones roll down the window. This is because surface tension holds the small drops onto the screen until they get to a size where the force of gravity is greater than the surface tension.

But mathematicians at the University of Bristol have shown that the small drops can defy gravity and travel up hill – even on an incline as steep as 85 degrees – if the surface vibrates up and down sufficiently strongly.

Dr Philippe Brunet, in the Department of Mathematics said, “Moving small droplets – such as thousands of spots of DNA arranged on a solid surface (a DNA microarray) – is very difficult as their small size causes them to stick to the surface. So improving our understanding of what causes droplets to move on surfaces will help with this and similar problems.”

Professor Jens Eggers, also from the University’s Maths Department added: “As the shaking plate rises the drop is compressed, while it bulges upward as the plate falls. If the shaking is vigorous enough to overcome the surface tension experienced as the drop is compressed, the drop will tend to lean forward, producing a net force which drives the drop uphill.”

The research will be published online this week in Physical Review Letters.

Since the droplet must withstand a fair amount of force, alternately pushing and pulling, it is in danger of breaking apart. Thus the droplet cannot be too large and the fluid has to be a bit thicker than water. Pure water droplets will break apart before the forces are strong enough to cause them to climb. On the other hand, the drops move very slowly if the fluid is too thick.

This method for moving droplets using vibrations may prove useful in understanding the small-scale manipulation of fluids.

Cherry Lewis | EurekAlert!
Further information:
http://www.bristol.ac.uk

More articles from Physics and Astronomy:

nachricht DGIST develops 20 times faster biosensor
24.04.2017 | DGIST (Daegu Gyeongbuk Institute of Science and Technology)

nachricht New quantum liquid crystals may play role in future of computers
21.04.2017 | California Institute of Technology

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

DGIST develops 20 times faster biosensor

24.04.2017 | Physics and Astronomy

Nanoimprinted hyperlens array: Paving the way for practical super-resolution imaging

24.04.2017 | Materials Sciences

Atomic-level motion may drive bacteria's ability to evade immune system defenses

24.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>