#Leidenfrost Effect

[mindblowingscience]

If you flick a handful of droplets on a very hot pan, you can watch them skitter and dance about. These droplets, believe it or not, are actually levitating. If a surface is hot enough, the heat will vaporize the side of the droplet closest to it, creating a cushion of gas on which the rest of the droplet hovers. This is known as the Leidenfrost effect, after German physician Johann Gottlob Leidenfrost, who documented the phenomenon in the 18th century. Now, a team of scientists has worked out a way to lower the temperature at which this little water dance occurs. A surface with a microscopic texture transfers heat to the droplets more effectively, a finding that has implications for heat transfer applications – such as cooling industrial machinery, and nuclear cooling towers.

Continue Reading.

[fuckyeahfluiddynamics]

The Best of FYFD 2023

A fresh year means a look back at what was popular last year on FYFD. Usually, I give a numeric list of the top 10 posts, but this year the analytics weren't as clear. So, instead, I'm combining from a few different sources and presenting an unordered list of some of the site's most popular content. (Image credits: sphinx - S. Boury et al., ear model - S. Kim et al., maze - S. Mould, dandelion - S. Chaudhry, water tank - P. Ammon, e. coli - R. Ran et al., drop impact - R. Sharma et al., Leidenfrost - L. Gledhill, toilet - J. Crimaldi et al., engine sim - N. Wimer et al., rivers - D. Coe, fin - F. Weston, snake - P. Schmid, nebula - J. Drudis and C. Sasse, flames - C. Almarcha et al.) Read the full article

[materialsscienceandengineering]

Scientific researchers draw inspiration from nature's brilliance as they seek to develop transformative solutions to unresolved challenges. Prof. WANG Zuankai, Associate Vice President (Research and Innovation) and Chair Professor of the Department of Mechanical Engineering of The Hong Kong Polytechnic University (PolyU), has meticulously explored the intricacies of nature and made remarkable findings with very significant real-world applications. His recently published research on cooling ceramic successfully translates novel discovery into sustainable applications. Findings from his research project "Hierarchically structured passive radiative cooling ceramic with high solar reflectivity" were published in the journal Science. Together with Prof. Christopher CHAO, Vice President (Research and Innovation), Chair Professor of Thermal and Environmental Engineering of PolyU and co-author of the paper, Prof. Wang collaborated with a research team from the City University of Hong Kong on this innovation.

Read more.

[ammg-old2]

Figuring out how to land humans on the moon was a challenge, but the six Apollo crews who achieved this aim encountered another perplexing problem once they arrived: moon dust. The tiny, electrostatically charged particles made of crushed lunar rock clung to every surface, from spacesuits to electronics, and even infiltrated the astronauts’ lungs. Crews tried using a brush or their hands to sweep the sharp, abrasive dust off their spacesuits, but neither method proved very effective.

Now, as NASA once again prepares to send humans to the moon with the Artemis program, researchers at Washington State University say they’ve come up with a promising solution to the dust issue. In laboratory experiments, they effectively removed dust from surfaces using pressurized liquid nitrogen, according to a new paper published in February in the journal Acta Astronautica.

To see whether liquid nitrogen��typically used as coolant—might be up to the task of removing moon dust, the scientists created miniature, replica spacesuits and placed them on Barbie dolls. Then, they coated the suits with volcanic ash from Mount St. Helens and other substances meant to imitate lunar dust. After placing the dolls in a vacuum chamber, they used a sprayer full of pressurized liquid nitrogen to blast away the particles.

In 233 total tests on 26 simulated spacesuits, the pressurized liquid nitrogen removed more than 98 percent of the moon dust substitute. Perhaps even more exciting is that the technique caused little damage to the spacesuits. This is important because “traditional spacesuit cleaning methods, such as brushing and vacuuming, have limited effectiveness and introduce suit fabric abrasion,” the researchers write in the paper.

The mechanism at play is known as the Leidenfrost Effect, in which a liquid droplet hovers over a very hot surface, rather than making contact with it. This happens, for example, when a chef pours cold water into a very hot pan—rather than coating the bottom, the water beads up and skitters across the surface. The researchers say the same thing occurred when they sprayed cold liquid nitrogen onto the warmer spacesuits: The nitrogen encapsulated the dust particles in droplets, then floated away.

This relatively gentle method can be used 75 times without causing damage to the suit, writes Space.com’s Elizabeth Howell. A brush, for comparison, damages a spacesuit with just one use.

Though the initial findings are promising, they represent only a first step toward implementing the technique on future lunar landings. For one, the researchers tested the liquid nitrogen on Earth, which has much stronger gravity than the moon. Astronauts would also face logistical challenges bringing pressured liquid nitrogen aboard a spacecraft.

Even so, NASA is eager to come up with a solution to the moon dust problem and wants to collaborate with partners that might be able to help. In 2019, the space agency launched the Lunar Surface Innovation Initiative to develop new technologies that could support astronauts and vehicles that land on the moon—and dust is one of its key areas of focus. Staff working on the initiative are considering “active and passive mitigation technologies for different exploration systems, like rovers, power systems, spacesuits and other surface hardware exposed to dust,” according to NASA.

NASA engineers have been testing some ideas, including slippery coatings to prevent dust from sticking to surfaces in the first place and electrostatic devices to repel particles. They’re also considering using waves of ultrasonic energy to remove dust. In the end, they may need to use all of these techniques—and then some—to protect the materials astronauts bring to space and finally vanquish their pesky lunar dust foe.

“There’s not going to be one solution,” said Sharon Miller, who is leading NASA’s dust-mitigation efforts, to Wired’s Eric Niiler in 2021. “For every material that you need to have up there, we’ll have to do something different.”

[nudeartpluspoetry]

Who knew?

The Leidenfrost effect is a physical phenomenon in which a liquid, close to a surface that is significantly hotter than the liquid's boiling point, produces an insulating vapor layer that keeps the liquid from boiling rapidly | source

[egodb]

I do not fit in

Wet finger in molten lead

Cannot last too long

[materiallugy]

Did you know that you can touch a molten metal with your hand using the Leidenfrost  effect? 

There is an educational demonstration involves dipping a wet finger into molten metal. The rapid vaporization of the water forms a protective layer of steam, preventing the metal from causing burns. This demonstration showcases the Leidenfrost effect in a visually striking manner.

And thus, you can wet your hand with water and then quickly pass it over hot molten metal without feeling anything or hurting your skin, but it is still dangerous do not try it.

[kotaerukoto]

It's early June. The summer heat has set in, and the sun shines in the sky for longer. The days can feel picturesque, even, with the kind of weather that helps someone to think, "today will be a good day." And a certain ordinary guy is has one specific thing in mind...

I want to go to the beach this year...!!

[dandelionsresilience]

Good News - May 22-28

Like these weekly compilations? Support me on Ko-fi or $Kaybarr1735! Also, if you tip me on Ko-fi or CashApp (and give me some way to contact you if it doesn’t automatically), at the end of the month I'll send you a link to all of the articles I found but didn't use each week - almost double the content!

1. Scientists Invent Healthier More Sustainable Chocolate

“The new chocolate recipe from researchers at ETH Zurich uses more materials from the cocoa pod that are usually discarded, including more of the pulp as well as the inner lining of the husk, known as the endocarp. […] The resulting chocolate also [was “deliciously sweet” and] had 20% more fibre and 30 percent less saturated fat than average European dark chocolate[, and] it could enable cocoa farmers [to] earn more from their crops.”

2. Vermont Is Coming for Big Oil, Making It Pay for Decades of Climate Pollution

“Legislators in Montpelier are on the brink of enacting the "Climate Superfund Act," modeled after the federal Superfund law, that seeks to make oil, gas and coal companies pay for damages linked to historical greenhouse gas emissions. […] Companies would be held liable for the costs associated with […] floods and heat waves, along with losses to biodiversity, safety, economic development and anything else the treasurer deems reasonable[, that were caused by their emissions].”

3. Important bird habitat now protected in the Rocky Mountain Trench

“Grassland-reliant species in the Rocky Mountain Trench now have more protected habitat thanks to a new [270-hectare] conservation area near Cranbrook. […] About one-third of the Skookumchuck Prairie Conservation Area is forested[…,] Most of the site is a dry grassland[…, and] Three hectares of wetlands add to the landscape diversity and offer crucial benefits to wildlife and water systems in the area. This conservation gem also provides habitat for endangered American badger and excellent winter range for elk, mule deer and white-tailed deer.”

4. Lemur Week marked by 70th breeding success

“A wildlife park has celebrated its 70th lemur breeding success ahead of a week raising money to help save the endangered primates. […] The park's open-air Madagascar exhibit is home to 31 free-roaming lemurs and was officially opened in 2008. […] Females are only sexually receptive for just one or two days a year, leaving a small window of opportunity for males to father offspring. […] The two playful siblings, one female and one male, were born to father Bernard and mother Hira.”

5. Innovative material for sustainable building

“Researchers introduce a polymer-based material with unique properties. This material allows sunlight to enter, maintains a more comfortable indoor climate without additional energy, and cleans itself like a lotus leaf. The new development could replace glass components in walls and roofs in the future.”

6. Isle of Wight eagles don't pose threat to lambs as feared

“While there had previously been fears that the eagles would feed on livestock, such as lambs, the project has found no evidence of this. [… “W]hite-tailed eagles effectively steal meals from other predatory birds[, which is] a really important ecological role that had been lost within the landscape and is being restored.” [… The birds’] population was boosted by a chick last year – the first time the species has bred in England in 240 years.”

7. Breakthrough discovery uses engineered surfaces to shed heat

“Cheng's team has found a way to lower the starting point of the [Leidenfrost] effect by producing a surface covered with micropillars. […] The discovery has great potential in heat transfer applications such as the cooling of industrial machines and surface fouling cleaning for heat exchangers. It also could help prevent damage and even disaster to nuclear machinery.”

8. New malaria vaccine delivered for the first time

“A total of 43,000 doses arrived by air today from UNICEF, and another 120,000 are scheduled to show up in the coming days. […] They're the first vaccines designed to work against a human parasite. […] Across four African countries, these trials showed a 75% reduction in malaria cases in the year following vaccination of young children. […] The Serum Institute of India, who will be manufacturing the new vaccine, says a hundred million doses will likely be available to countries by the middle of next year.”

9. Urban gardening may improve human health: Microbial exposure boosts immune system

“"One month of urban indoor gardening boosted the diversity of bacteria on the skin of the subjects and was associated with higher levels of anti-inflammatory cytokines in the blood. The group studied used a growing medium with high microbial diversity emulating the forest soil," [… whereas] the control group used a microbially poor peat-based medium. [… N]o changes in the blood or the skin microbiota were seen. […] “This is the first time we can demonstrate that meaningful and natural human activity can increase the diversity of the microbiota of healthy adults and, at the same time, contribute to the regulation of the immune system."”

10. Cities Are Switching to Electric Vehicles Faster Than Individuals

“[M]ost large cities have adopted some kind of climate goal, and some of them are buying EVs for their municipal fleets at a faster rate than the general public. And that progress could speed up as more EVs enter the market and as cities get educated about grant funding and tax incentives that were passed over the last four years.”

May 15-21 news here | (all credit for images and written material can be found at the source linked; I don’t claim credit for anything but curating.)

[shankss-magnificent-ass]

Imagine Kaido sees potential in you and drafting you into his crew

You and your comrades: [defending your home by successfully holding off the Tobiroppo]

Kaido: hmm [evaluating your fighting techniques from a distance]

King: They're taking too long to get this over with. [Draws his sword and advances on your homes]

You: [watches King taking down your friends one by one using his fire, ] I need to do something, [looks around to see only a small fishpond in a neighbor's yard]

King: [sends a blast of flames in the direction of someone's home, only to stumble back in surprise when you leap through his flames, landing on his chest, with your weapons poised to gouge out his eyes.]

Kaido: King, stop, I want that one alive.

King: [grabs you, and holds you at arm's length, stunned you're alive,] Why the hell would you want this one alive!?

Kaido: Think about it. How many people can you say, with certainty, have been brave enough to charge your fire attacks, let alone come out unscathed?

King: [eyes you with irritation] Not a single person.

You: Fuck both of you, put me down! [narrowly miss clipping King's mask with your weapon]

Kaido: I think we've found the most valuable thing in this village, there is no need to waste any more time here.

King: [huffs in frustration before turning to the crew] Alright, it's time to pull back, Kaido has what he's looking for.

Sasaki: Ehh! But there is still so much we could take! We found a whole cellar of booze.

Kaido: [looks at you out of the corner of his eye before making up his mind] Leave it.

Black Maria: This isn't like you at all, leaving booze behind, I hope you'll share with me what's happening.

Kaido: What's going on is I want this one to join our crew [tossing his thumb over his shoulder, in your direction]

You and the Beast Pirate crew: WHAT!

You: Why would I join your crew?

Kaido: Not would, will. You will join my crew. Also, if you do, I will not only leave your village alone, it will fall under my protection, and I won't tax them.

King: You're not gonna even tax them a little bit?

Kaido: Not if they accept my deal.

You: [grits your teeth] Fine.

Kaido: Okay then, let's move out.

On Kaido's Ship

King: how did you make it through my fire?

You: I used Leidenfrosts effect in a two-part defense. I grabbed a quilt my neighbor had hanging out to dry on their laundry line, then dowsed it and myself in a nearby fishpond. I climbed up on the roof and used the quilt to make it through the brunt of your attack, to jump off the roof. When the water evaporated, I then tossed the quilt to the side and attacked you.

King: Leidenfrost effect?

You: When your fire hit me, it rapidly evaporated the water, creating a protective layer of steam around me. I wasn't sure it'd even work, I figured, fuck it, it was worth a shot. [shrugs]

Kaido: [cackles] I knew there was more to you than meets the eye.

King: so you damn near beheaded me with science?... I think I'm starting to see what Kaido sees in you.

You: please don't

List of Up-and-coming works || Master list || Twitter| Kofi || Patreon

[over-sleep]

ライデンフロスト効果　　Σ(ﾟДﾟ) ﾌｪｪｪｯ!? Leidenfrost Effect

（ funkystay さんのImgur ）

[fuckyeahfluiddynamics]

Leidenfrost Collapse

When a droplet encounters a surface much hotter than its boiling point, it forms a thin layer of vapor that insulates the liquid from the surface. But this Leidenfrost effect can't last forever. (Image credit: L. Gledhill; research credit: D. Harvey and J. Burton) Read the full article

[materialsscienceandengineering]

The Leidenfrost Effect

This week Reactions is all about the chemistry and science of the Leidenfrost Effect. Have you ever seen a drop of water navigate a maze? It’s possible thanks to a weird phenomenon called the Leidenfrost Effect. Understanding Leidenfrost — first described more than 200 years ago — helped engineers make more efficient steam engines. Today, scientists are using high-speed cameras to work out how super hot water behaves on metal surfaces. These little levitating water droplets are a big deal -- this could also help prevent future nuclear disasters.

[he4d-banger]

Leidenfrost

So...a few weeks ago @salaapaoo got this idea of OgCale been thrown away to an orphanage by Deruth when Violan was going to arrive at the Henituse Mansion.

After a lot of suffering he was rescued by Ron and Beacrocx, and he felt so relieved that he wasn't forgotten completely.

Now... I wanted to add spice and make a fic a little longer, I would really like to give him some kind of Ice ancient power, replacing the Sky Eating Water to give it to Hong so he can water-poison bend (?) and the Sound of The Wind to Ohn so she can create storms. I really like this idea because thanks to Leidenfrost effect, OgCale's ice should be able to win against White Star's Sword of Disasters that is fire based (more like lava, which is even better because ice cools lava before it melts). Imagine all the cool stuff Ohn and Hong would be able to perform too, I can picture a complicated situation at the Land of Death, been surrounded by enemies and Ohn just creates "The Sand Storm" to escape.

On the other hand, I would like to deepen the connection with the dead, like adding wise ghosts, because our OgCale is smart, but he doesn't have all the future knowledge, so I wanted to give him the advantage to hear what the victims of Arm have to say and collect information, it would be also useful to replace the wind elementals.

Finally I would like to take a few more years than KrsCale took for this war. This is for the sake of more looting and stealth missions, and to develop everyone mental strength so it wouldn't be too traumatic for them to use their powers. I also took into consideration that Cale wouldn't have Henituse backing him, and I don't want him relying entirely on other figures like Fredo and Eruhaben since he would get trust issues. He will need time to build an stratospheric wealth and to fight our favorite clown, he will need training and time to bond.

What do you think? does it makes sence? Would you read something like that? I am kinda scared since English is not my first language, but I tried my best.

[metapianycist]

yesterday when i was cooking, some oil splattered and a drop landed on my eyelid.

thank fuck for blink reflexes and the leidenfrost effect, for preventing me from getting an eye injury or developing any kind of real burn

[shacklesburst]

The Leidenfrost effect for sure is one of the most nominative determinisms of all time. There is simply no other guy who could've described that one sooner.