Thus, water is “thin”, having a lower viscosity, while honey is “thick”, having a higher viscosity. But when a droplet is confined to one of the very narrow tubes used in microfluidics, things change drastically. In fact, through these specially coated tubes, liquids a thousand times more viscous flow ten times faster. With less air managing to squeeze past the low-viscosity droplets, these were forced to move down the tube with a slower speed than their more viscous counterparts,” explains Dr. Matilda Backholm, one of the researchers on the project. Botanical origin was found to have a relatively small effect on honey viscosity, the characteristic being more influenced by water content and temperature. A quick internet search shows that the viscosity of honey is 10,000 cP at a room temperature of 21.1°C. Superhydrophobic coatings themselves don’t speed up the flow of the more viscous liquids. Traditionally, if you need to make a fluid flow faster through a pipe, you increase the pressure on it. The researchers filmed the droplets as they moved through the tube, tracking not only how fast the liquid moved through the tube, but also how the liquid flowed inside the droplet. The team developed a fluid dynamics model that can be used to predict how droplets would move in tubes coated with different superhydrophobic coatings. . 'A superhydrophobic surface consists of tiny bumps that traps air within the coating, so that a liquid droplet that rests on the surface sits as if on a cushion of air,' explains Professor Robin Ras, whose research team at Aalto University's Department of Applied Physics has made a range of interesting discoveries in the area of extremely water repellent coatings, including recent papers in Science and Nature. The information you enter will appear in your e-mail message and is not retained by Phys.org in any form. Researchers were surprised to find this behavior flipped on its head when the liquids flow through chemically coated capillaries. ... What is important to remember about the effect of temperature have on the viscosity of gases vs liquids? Copyright © 1998 - 2020 SciTechDaily. This means that the air beneath a low-viscosity droplet in the tube couldn’t move out of the way as fast as for a more viscous droplet with a thicker air gap.

"The crucial discovery is that the less-viscous liquids also managed to penetrate a bit into the air cushion surrounding the droplets, rendering a thinner air gap around these. The researchers filmed the droplets as they moved through the tube, tracking not only how fast the liquid moved through the tube, but also how the liquid flowed inside the droplet. In the paper published on 16 October in the journal Science Advances, researchers found that by coating the inside of the pipes with compounds that repel liquids, they could make viscous liquids flow faster than those with low viscosity. Researchers were surprised to find this behavior flipped on its head when the liquids flow through chemically coated capillaries. The time it takes for a fluid to flow over a set distance is called? They hope that further work on these systems could have significant applications for microfluidics, a type of chemical engineering technique that is used to precisely control liquids in small quantities and in manufacturing complex chemicals like medicines.

This larger air gap is what allowed for the viscous fluids to move through the tube faster than the less viscous ones when flowing due to gravity,” says Dr. Maja Vuckovac, the first author of the paper. This larger air gap is what allowed for the viscous fluids to move through the tube faster than the less viscous ones when flowing due to gravity,' says Dr Maja Vuckovac, the first author of the paper. Put simply, the less viscous the fluid is, … ScienceDaily. Email address is optional. When honey flows faster than water. If you place a drop of honey and a drop of water on a superhydrophobic coated surface and then tilt the surface so gravity makes the droplets move, the low-viscosity water will flow down faster. ScienceDaily. But when a droplet is confined to one of the very narrow tubes used in microfluidics, things change drastically. Why find the highest order maxima/minima in slit equations? With further cooling, the increase in viscosity is more rapid, reaching 600 poise at around 14 °C (57 °F).

By cutting into fossils and examining growth rings, scientists learned how predatory dinosaurs got so big. For viscous liquids, the liquid inside the droplet hardly moved around at all, whereas a fast mixing motion was detected in the lower viscosity droplets. part may be reproduced without the written permission. A mathematical description of the physics behind Aurora?

Traditionally, if you need to make a fluid flow faster through a pipe, you increase the pressure on it.