Fluid dynamics – The Conversation

Poohsticks, the game in which Piglet and Winnie the Pooh throw sticks into the river from one side of a bridge, and then rush over to the other side to see whose stick appears first, is all about current flow. Disappointingly, neither Piglet nor Pooh mention fluid dynamics despite its pivotal importance in determining who won. Unlike sticks, though, animals can respond to those flows. The movemen…

Whether diving off docks, cannonballing into lakes or leaping off the high board, there’s nothing quite like the joy of jumping into water. Olympic divers turned this natural act into a sophisticated science, with the goal of making a splash as small as possible. But another sport looks for just the opposite: the extreme maximum splash, one as high, wide and loud as possible. Welcome to the world…

If you are a frequent flyer, you’ve probably been at the airport waiting to jet somewhere on a winter trip when the voice of an airline employee announces over the intercom that there will be a slight delay while the plane gets deiced. But how does this process actually work, and why is it needed? As a mechanical engineer who studies frost growth and water droplets on surfaces, I have come to app…

Scientific discovery doesn’t always require a high-tech laboratory or a hefty budget. Many people have a first-rate lab right in their own homes – their kitchen. The kitchen offers plenty of opportunities to view and explore what physicists call soft matter and complex fluids. Everyday phenomena, such as Cheerios clustering in milk or rings left when drops of coffee evaporate, have led to discove…

With 113 million viewers in the United States and 40 million more around the world, the Super Bowl is the most popular sports event in North America. This year’s event on Sunday – with the added attraction of a romance in the spotlight – promises to attract as many fans. In Canada, the most recent Grey Cup final, last November, reached a record audience of 3.7 million viewers who tuned in to watc…

Microplastics are tiny plastic particles that can cause big problems when they enter the water supply. One way my fluid dynamics lab explores microplastic movement is by studying how tiny water-walking insects are pushed underwater by raindrops. Exposure to microplastic pollution can pose health risks, such as respiratory and digestive problems, increased risk of diabetes and disrupted sleep. But…

Underwater surfaces can get grimy as they accumulate dirt, algae and bacteria, a process scientists call “fouling.” But furry mammals like beavers and otters that spend most of their lives wet manage to avoid getting their fur slimy. These anti-fouling abilities come, in part, from one of fur’s unique properties — that each hair can bend and flex as an animal moves. I’m a mechanical engineer who …

In countries near the Earth’s equator, tourists are often dazzled by a demonstration of a mysterious physical phenomenon. A presenter will position three buckets of water – one in the Northern Hemisphere, one in the Southern Hemisphere, and one directly on the equator – and let the water drain out. Tourists are shown that, as the water drains, the water in the northern bucket rotates in one direc…

Cell migration, or how cells move in the body, is essential to both normal body function and disease progression. Cell movement is what allows body parts to grow in the right place during early development, wounds to heal and tumors to become metastatic. Over the last century, how researchers understood cell migration was limited to the effects of biochemical signals, or chemotaxis, that direct a…

Imagine the following scenario. A phone rings. An office worker answers it and hears his boss, in a panic, tell him that she forgot to transfer money to the new contractor before she left for the day and needs him to do it. She gives him the wire transfer information, and with the money transferred, the crisis has been averted. The worker sits back in his chair, takes a deep breath, and watches a…

To win swimming gold in Tokyo, swimmers not only have to generate incredible power with their arms and legs to propel themselves through the water; they also have to overcome the relentless pull of the water’s drag while doing so. Without being able to don special low-drag suits or use technologies to help them fly over the water, how can swimmers make the effect of the water’s drag as small as p…

Editor’s note: Varghese Mathai is a physicist at the University of Massachusetts Amherst who studies the flow of fluids and gases. He conducted a study using computational fluid dynamics simulations to understand how air flows inside a car and its implications for COVID-19 airborne transmission. In this interview, he explains the optimal ways to ensure maximum airflow inside a car. What can be do…

COVID-19 has sharply brought into focus the impact of respiratory infectious diseases on humanity. It has also shown that the greatest defence against health crises is government policy that is strongly rooted in science. In an attempt to contain the spread of the disease many governments have implemented policies that prevent physical interaction. This has a direct impact on our daily lives: the…

Leer en español When someone coughs, talks or even breathes, they send tiny respiratory droplets into the surrounding air. The smallest of these droplets can float for hours, and there is strong evidence that they can carry live coronavirus if the person is infected. Until mid-July, however, the risk from these aerosols wasn’t incorporated into the World Health Organization’s formal guidance for …

In the last 10 years, but in the last five months in particular, the press has reported dire warnings that the Great Red Spot of Jupiter is dying. However, some astronomers believe, to paraphrase Mark Twain, that the reports of its death are greatly exaggerated, or at least premature. Robert Hooke, an early British physicist who discovered cells, first described the Great Red Spot in 1665. In 197…

When I was playing “splash rocks”, I noticed that when I threw the rock into the river it made a circle shape, which got bigger. How does it make the ripple? Why do the circles spread out further and further? Why do they stop? – Rowan, aged six, UK. Hi Rowan, these are good questions, and a fun experiment to do. When you throw a rock into a river, it pushes water out of the way, making a ripple t…

Paleontologists like us are used to working with fossils that would seem bizarre to many biologists accustomed to living creatures. And as we go farther back in Earth’s history, the fossils start to look even weirder. They lack tails, legs, skeletons, eyes…any characteristics that would help us understand where these organisms fit in the tree of life. Under these circumstances, the science of pal…

The ancient Chinese practiced copromancy, the diagnosis of health based on the shape, size and texture of feces. So did the Egyptians, the Greeks and nearly every ancient culture. Even today, your doctor may ask when you last had a bowel movement and to describe it in exquisite detail. Sure, it’s uncomfortable to talk about. But that’s where science comes in, because what we don’t like to discuss…

From the raindrops that soak you on your way to work to the drops of coffee that inevitably end up on your white shirt when you arrive, you’d be forgiven for thinking of drops as a mere nuisance. But beneath a mundane facade, droplets exhibit natural beauty and conceal complex physics that scientists have been trying to figure out for decades. Recently, I have contributed to this field by working…

How does one get stuck studying frog tongues? Our study into the sticky, slimy world of frogs all began with a humorous video of a real African bullfrog lunging at fake insects in a mobile game. This frog was clearly an expert at gaming; the speed and accuracy of its tongue could rival the thumbs of texting teenagers. Further YouTube research yielded amazing videos of frogs eating mice, tarantula…