Tag: DIY fluids

Perfecting Giant Bubbles
Whether young or old, everyone enjoys blowing soap bubbles, and the bigger the bubble, the more impressive it is. Researchers have been on a quest to discover how bubbles can survive with volumes measured in the tens of meters and thicknesses of mere microns.
The key to these behemoth bubbles are the polymer chains inside them. The long molecules of polymers get entangled with one another and resist further stretching, which strengthens the soap film. The researchers found that a mixture of polymer lengths are even better for long-lasting bubbles because they entangle more fully than polymers that are all the same size.
But if what you really want are practical results, I have good news for you: the researchers have released their recommended recipe for making the best giant soap bubbles. It’s included in the video below, but I’ve also reproduced it in text for easier recreation (with thanks to Ars Technica):
Giant Soap Bubble Solution
From the Burton Lab, via Ars Technica

Ingredients
1 liter of water (about 2 pints)
50 milliliters of Dawn Professional Detergent (a little over 3 TBSP)
2-3 grams of guar powder, a food thickener (about 1/2 heaping TSP)
50 milliliters of rubbing alcohol (a little more than 3 TBSP)
2 grams of baking powder (about 1/2 TSP)
Directions
Mix the guar powder with the alcohol and stir until there are no clumps.
Combine the alcohol/guar slurry with the water and mix gently for 10 minutes. Let it sit for a bit so the guar hydrates. Then mix again. The water should thicken slightly, like thin soup or unset gelatin.
Add the baking powder and stir.
Add the Dawn Professional Detergent and stir gently to avoid causing the mixture to foam.
Dip a giant bubble wand with a fibrous string into the mixture until it isf fully immersed and slowly pull the string out. Wave the wand slowly or blow on it to create giant soap bubbles.
Happy bubble making! (Image credit: Burton Lab; video credit: Emory University; research credit: S. Frazier et al.; via Ars Technica; submitted by Kam-Yung Soh)

February 7, 2020
Making a Square Vortex
As someone who has played with her share of vortex cannons, I can assure you that messing around with smoke generators and vortex rings is a lot of fun. And in this video, Dianna gives things a little twist: she makes the vortex cannon’s mouth a square instead of a circle.
Now, that doesn’t create a square vortex ring. (Vortex rings don’t really do 90-degree corners.) But it does make the vortex ring all neat and wobbly. Whenever you have two vortices near one another (or, in this case, two parts of a vortex line near one another), they interact. As Dianna shows with hurricanes, depending on the direction of rotation and their relative strength, nearby vortices can orbit one another or travel together in straight lines – or they can cause more complicated interactions, like in the case of the square-launched rings.
I think there may also be some interesting effects here from vortex stretching, but that’s a topic for another day! (Video and image credit: D. Cowern/Physics Girl; see also: LIBLAB; submitted by Maria-Isabel C.)
November 9, 2018
Water Bottle Flipping Physics
In 2016, a senior talent show launched a new viral craze: water bottle flipping. As improbable as it seems at first glance, physics is actually on your side when it comes to pulling this trick off. As explained in this classroom-oriented paper and the video abstract below, the sloshing of the water in the bottle as it flips slows its rate of rotation, which creates the stable landing. You don’t even need water to make the trick possible. Using two tennis balls will also give a stable flip – provided they have room to spread out. When they fly apart, they change the bottle’s moment of inertia and that slows down the rotation rate. All in all, it’s a great lesson in conservation of angular momentum.
And, in case you’re wondering whether the water helps with sticking that landing, we’ve got you covered there, too. (Image credit: A. Johnson, source; video and research credit: P. Dekker et al.)
September 28, 2018
Waves Below the Surface
Even a seemingly calm ocean can have a lot going on beneath the surface. Many layers of water at different temperatures and salinities make up the ocean. Both of those variables affect density, and one stable orientation for the layers is with lighter layers sitting atop denser ones. Any motion underwater can disturb the interface between those two layers, creating internal waves like the ones in this demo. In the actual ocean, these internal waves can be enormous – 800 meters or more in height! In regions like the Strait of Gibraltar where flowing tides encounter underwater topography, large internal waves are a daily occurrence. Internal waves can also show up in the atmosphere and are sometimes visible as long striped clouds. (Video and image credit: Cal Poly)
May 22, 2018
DIY Acoustic Levitation
Acoustic levitation is a technique where multiple speakers are positioned to create standing waves that can levitate small objects using sound. It’s even possible to manipulate the levitating objects in three-dimensions with the right set-up, but until now, the technology has been confined to the laboratory. Now a group from the University of Bristol has created kits and instructions allowing the curious to build their own acoustic levitators at home. In the video, Dianna shares some of her own adventures in building and playing with these DIY levitators and travels to the U.K. to see more from the creators.
I know what I’m adding to my list of electronics projects to try out! (Video credit: Physics Girl)
January 2, 2018
Build Your Own Fluidized Bed
Previously, we featured some GIFs of bubbling, fluidized sand (below). Inspired by the same video, Dianna from Physics Girl decided to build her own set-up, discovering along the way that it’s a little tougher than you might think. To work well, you’ll need very fine, dry particles and a good way to uniformly distribute the air so it doesn’t simply bubble up in one spot. And if you accidentally apply too much air pressure, you may get a face full of sand. The final results are very fun, though, and hopefully Dianna’s lessons learned will help any other DIYers interested in trying this experiment at home. For a little more on the physics here and in related topics, check out some of our previous posts on fluidization, soil liquefaction, quicksand, and dam failures. (Video credit: Physics Girl; image credit: R. Cheng, source)
November 6, 2017
Kelvin-Helmholtz Instability
Sixty Symbols has a great new video explaining the laboratory set-up for demoing a Kelvin-Helmholtz instability. You can see a close-up from the demo above. Here the pink liquid is fresh water and the blue is slightly denser salt water. When the tank holding them is tipped, the lighter fresh water flows upward while the salt water flows down. This creates a big velocity gradient and lots of shear at the interface between them. The situation is unstable, meaning that any slight waviness that forms between the two layers will grow (exponentially, in this case). Note that for several long seconds, it seems like nothing is happening. That’s when any perturbations in the system are too small for us to see. But because the instability causes those perturbations to grow at an exponential rate, we see the interface go from a slight waviness to a complete mess in only a couple of seconds. The Kelvin-Helmholtz instability is incredibly common in nature, appearing in clouds, ocean waves, other planets’ atmospheres, and even in galaxy clusters! (Image and video credit: Sixty Symbols)
July 20, 2017
How Smoke Rings Work
Vortices are a ubiquitous part of life, whether they’re draining down your bathtub or propelling underwater robots. In the latest video from the Lib Lab project, you can learn about how vortex rings form, what makes them last so long, and even make a vortex generator of your own. I can personally attest that vortex cannons are good for hours of entertainment, no matter your age. They’re even more fun with friends, as the Oregon State drumline demonstrates in the video. Want even more vortex fun? Check out leapfrogging vortices, vortex rings colliding head-on, and a giant 3 meter wide vortex cannon in action. (Video and image credit: Lib Lab)
July 19, 2017
How Jet Engines Work
Jet engines are a major part of aviation today, and this great video from the new LIB LAB project breaks down how jet engines operate. It focuses especially on the subject of combustion, in which fuel-air mixtures are burned to generate power and thrust. By breaking fuels down into simpler compounds, jet engines are able to accelerate exhaust gases, which creates thrust. They even provide instructions for an effervescence-driven bubble rocket so that kids can (safely!) experiment with propulsion at home. (Video credit: LIB LAB/Corvallis-Benton County Public Library)
March 3, 2017
Make Your Own Dancing Droplets
As a follow-up to last week’s “dancing droplet” post, here’s a video that describes how to recreate the experiment yourself at home. The droplet motion is driven by the two-component structure of the droplets, where differing evaporation rates and surface tension values between the two fluids in the drop cause the attractions and chasing behavior you see. To demonstrate this at home, you’ll need glass, fire (for sterilization), tweezers, a pipette, water, and food coloring. Looks like a fun way to spend a weekend afternoon! (Video credit: M. Prakash et al.; via io9)
April 6, 2015