By David Whiteis
People have known about bubble rings for a long time: Dolphins and whales make them with their blowholes, and a great many humans have taught themselves to make them underwater using their mouths.
I’m one of those humans and have known how to make them since childhood: Back when my mother would send all of us kids down to the community pool, I figured out how to blow the equivalent of a smoke ring underwater. Later on, I decided to invent a device that would do the same thing so that other swimmers could enjoy the rings without learning how to generate them.
A bubble ring is basically a doughnut-shaped pocket of air, moving upwards in a body of water. The air inside a bubble ring spins as it travels through the water – not like a spinning plate, but rather the way a bead bracelet rolls on your arm. (Smoke in a smoke ring spins in this same way.) As bubble rings rise, their circumference widens and the rings get thinner.
As one might expect, there are a number of variables that influence how well these rings hold together. As an inventor, my goal has been to create devices that can consistently produce rings that will move up through the water and reach the surface intact within a certain range of depths.
Bubble rings may be simple in concept, but describing their appeal is not so easy.
Most people who see them express the feeling that there’s just something fun and delightful about them. (I’ve also frequently heard the words hypnotic, charming and mesmerizing.) I don’t want to get too high-flown here, but part of the fascination may extend from the fact that circles are powerfully suggestive to human beings in symbolic terms and have an obvious place in mysticism, religions and cultures worldwide. As such, they may resonate with us on levels we don’t quite understand – and in my book, that just makes these rings all the more interesting.
|Developed to mimic the bubble rings that emerge from the blowholes of large marine mammals, the rings formed using my mechanical devices are coherent because of the way the air circulates within them as they rise through the water. And they can be just about any size, too, depending on a variety of factors.|
At root, however, I just see them as fun. Indeed, I liken the experience of watching and playing with bubble rings to observing butterflies or looking at magnified snowflakes: All are beautiful natural forms – tangible and recognizable, yet utterly ephemeral at the same time. Moreover, bubble rings can’t be captured, stopped or held: If you try to do so, you destroy the effect. And even if you leave them alone, they last for only a matter of seconds before disappearing.
You can hang out with dolphins and whales for days on end and never see one, which is why I was so determined to make a machine that would enable me to enjoy the experience of their generation, growth and disappearance over and over again at will.
Once I put these rings in the water, I noticed that their appeal is universal: Young or old, in the water or just next to it – for whatever reason, when people see bubble rings rising in the water, they almost invariably stop and take a closer look. In the water, both children and adults find all sorts of ways to play with them, sticking their hands through the hoops, racing to see who can disrupt the ring first or creating currents that distort the shapes of the rings as they rise.
|The devices come in many shapes and sizes, including versions that are essentially toys. One device, for example, is simply held under the water and generates bubble rings when a lever is actuated; another has been housed inside a plastic whale and produces its bubble rings with similar ease.|
And again, we humans aren’t alone in being enthralled by bubble rings: I installed one of my systems at the National Aquarium in Baltimore, and we observed that marine mammals – especially dolphins – can’t seem to get enough of these rings. This device automatically generates them at timed intervals, and the dolphins seemed to have a great deal of fun racing to see which would be the first to bite the rings and break them into splashes of small, separate bubbles.
As mentioned above, both dolphins and whales actually make bubble rings – or what scientists refer to as “vortex rings” – with their blowholes. In some cases, whales’ bubble rings are so large that if you happened to be in a kayak at the point where one surfaced, you might be capsized by the resulting turbulence. Why they do it is still anyone’s guess, but the fact that these simple forms are part of the natural aquatic environment seems to add yet another level of interest.
HOW THEY WORK
My day job is in the computer industry, but for many years I’ve spent my spare time as an inventor. The device I call “The Ring Machine” is the result of years of tinkering; so far, I’ve developed a number of different models capable of generating bubble rings in bodies of water of almost any type.
Before I came up with my mechanisms, one of the few ways others had invented to generate bubble rings involved delivering compressed air to a solenoid-controlled valve. These devices were noisy, cumbersome and relatively expensive – and not for every application, because you wouldn’t want the device making a loud “clack, clack” sound that might spook marine mammals and other sea creatures.
By contrast, all of my designs are simple, quiet and inexpensive – devices that one might best classify as “toys” rather than as “industrial instruments.” In fact, one of my patents shows a device that isn’t much more than an upside-down bucket filled with air and featuring a hole in the center of “top” of the bucket. That hole is plugged by a ball that is removed and replaced by actuating a mechanical device (either a lever or pedal) that moves the ball straight back from the hole and then quickly puts it right back in. This opening/closing action releases a sphere of air with minimal internal turbulence.
|A more sophisticated model is being developed to generate bubble rings in pools and spas. What you see here is a prototype for a system that can be mounted unobtrusively in the floors of these watershapes.|
The bubble ring forms when that sphere of air starts floating toward the surface and encounters resistance from the water through which it’s traveling. That resistance pushes the air at the top of the sphere out toward the flattening sphere’s edge. That air then curls around to the center of the sphere and travels back toward the top. Once the rings forms, if you could slice out a cross-section, you would see the moving air rotating up near the center of the ring and back down on the outside – a circulation pattern that holds true around the ring’s entire circumference.
If the currents in the water in which a ring is generated are too strong, the ring will break apart. If there’s not too much current or turbulence in the surrounding water, however, then the bubble ring remains intact, expanding and thinning until it reaches the surface, where it pops once it comes in contact with the atmosphere.
The physical qualities of a toroid (the scientific name for a doughnut shape) are what make this possible. Each section keeps the section next to it stable because of the perfect balances achieved in that circular form. In other words, I won’t be trying to create “bubble squares” or “bubble triangles” because it would not be possible: The points of tension associated with the corners would cause the structure to break apart immediately.
|My childhood fascination with bubble rings propelled me to develop these mechanical devices, and the greatest satisfaction I take is when I see children (or marine mammals) playing with the rings and becoming just as transfixed as I was by the experience.|
One of my hand-held designs is held underwater by a bather who pulls a small lever on the device to release a ring. If that bather lets go, the device floats to the surface. I originally developed a weighted model that would sit on the bottom of the pool, but that meant that someone would have to swim down and lift it back to the surface to refill it with air. I stopped pursuing that option because of the unit’s weight. I’ve also assembled a version that can be permanently mounted on the bottom of a pool, where it is fed by a small trickle of air in a feeder line.
Hand-held or mounted, these units can generate bubble rings that will travel up to 18 feet vertically before breaking up, making them applicable in just about any residential or commercial pool.
At this point, each bubble-ring unit is custom made and available supplies are limited. I have also produced a number of evaluation units in my effort to license designs to a manufacturer.
For Your Viewing Pleasure
To see find several views of bubble rings in action as well as David Whiteis’ Web site, click here.
In years of playing with these systems, I’ve always been fascinated by the amazing dance that occurs when two or more of the rings bump into one another. This is hard to describe in words, but it’s utterly delightful to watch as the combined internal tension and turbulence force the rings into complex, fleeting shapes. If one ring is larger than the other, for instance, it appears to warp and absorb the smaller one. If the two rings are the same size, they’ll twist and turn until the tension equalizes and they form up again as a single larger ring.
Although there’s almost certainly some complex physics involved here, for now I’m just satisfied to sit back and watch. The fact that I’m not alone in this interest and that it seems to be shared not just by people, but also by a variety of marine animals, is more than enough to keep me going.
David Whiteis is a computer networking engineer and part-time inventor living near Washington, D.C. He sold his first patent (on a method of recommending music to individuals based on the music they already enjoy) in 1998 to a company that is now a subsidiary of Microsoft. He currently works at the J. Craig Venter Institute, providing computer support to scientists conducting genetic research. Part-time, he continues his work toward inventing and developing new products and volunteers with a local inventors group as well as a group that helps in recycling old computer equipment. Whiteis reached the final 24 candidates during the first season of the ABC-TV show American Inventor with a jewelry box that takes a brief video of a woman’s reaction when she first sees her diamond engagement ring. His wife Kasia and their seven-year-old son Jake helped him take the photographs seen with his article in this issue.