by Fern Shaw | Dec 18, 2013 | Water
Using a Rough Surface to Stay Dry
*Researchers at the Massachusetts Institute of Technology and Boston University have found a new clue to staying dry, and it has to do with time and texture.
James C. Bird, now of Boston University, and Kripa K. Varanasi at M.I.T. and their colleagues, were considering the problem of icing, which is a version of getting wet, and they decided to focus on the time a water drop stays in contact with a surface.
There is a maximum amount of time a water drop can touch frozen material before it freezes and sticks, causing all sorts of problems for wings and machinery, for starters.
They tested ways to shorten the amount of contact time, and recorded the tests with high-speed video, which they analysed. A smooth surface might seem most likely to repel water, but they found that a rough surface, with ridges, for example, worked better.
The key is the way a water drop changes shape and bounces off material that has been treated to make it super water-repellent. The drop flattens into a pancake, then recollects itself and bounces up.
Ridges broke up the drops, and the smaller droplets re-formed and bounced away up to 40 percent quicker than the larger drops.
With refinements, Dr. Varanasi said they hope to be able to cut the contact time by 80 percent. If it can then be adapted for industrial uses, it could benefit wind turbines, other kinds of machines, and even the fashion industry.
After their discovery, the scientist looked to nature to see if plants and animals had evolved the same trick. And they had. Although the lotus leaf is often thought of as highly water-repellent, nasturtiums did better, with a rougher surface. They also found the wings of the Morpho Butterfly bounce water off in the same way.
While we like to stay afloat (harf harf) of all topics water, we are in no way suggesting that you use your water cooler as a test site for anything. Yes, that will include water spray ratio, rough surfaces; how high water will bounce off the carpet vs. the floorboards – none of it. We ask, as I’m sure your company does, that you use the water cooler for its primary purpose – supplying you with cool, fresh drinking water at the press of a button.
You may also wish to remember during these chilly winter months that AquAid also provide water boilers too. Anything you’d like to ask, drop us a line here.
*Excerpts from an article in the New York Times by James Gorman
by Fern Shaw | Dec 2, 2013 | Uncategorized
The water wheel was most likely first invented around 400BC. Its uses were multiple; including milling flour in gristmills and grinding wood into pulp for papermaking, but other uses include hammering wrought iron, machining, ore crushing and pounding fibre for use in the manufacture of cloth.
Water power was an important source of energy in ancient China civilization. One of the most intriguing applications was for iron. Water power was also applied at an early date to grinding grain. Large rotary mills appeared in China about the same time as in Europe (2nd century BC). But while for centuries Europe relied heavily on slave- and donkey-powered mills, in China the waterwheel was a critical power supply.
Chinese waterwheels were typically horizontal (illustration left). The vertical wheel, however, was known. It was used to operate trip hammers for hulling rice and crushing ore. The edge-runner mill was another commonly used crushing device. With the latter a circular stone on edge running around a lower millstone was used to pulverize. The edge runner appeared in China in the 5th century AD. Both the trip hammer and edge runner were not used in Europe until eight centuries later.
Throughout the first 13 centuries AD, technological innovations filtered slowly but steadily from the advanced East to the somewhat more backward West. Carried at first through central Asia over the 4,000-mile Silk Route and later by sea, some innovations were exported swiftly, while others (like waterwheel paraphernalia) took centuries.
The first description of a water wheel that can be definitely identified as vertical is from Vitruvius, an engineer of the Augustan Age (31 BC – 14 AD), who composed a 10 volume treatise on all aspects of Roman engineering. One of the most remarkable Roman applications of a waterwheel was at Barbegal (illustration right) near Arles in southern France. Dating from the 4th Century AD, the factory was an immense flour mill which employed 16 overshot water wheels.
Some water wheels are fed by water from a mill pond, which is formed when a flowing stream is dammed. A channel for the water flowing to or from a water wheel is called a mill race or simply a “race”, and is customarily divided into sections. The race bringing water from the mill pond to the water wheel is a headrace; the one carrying water after it has left the wheel is commonly referred to as a tailrace.
Now you know. Of course, we at AquAid don’t make use of water wheels to bring your water to you, nor do we employ water wheels to dispense your cool, fresh drinking water, but rather a range of water coolers, all designed to best suit your requirements.
