Antibubbles are droplets of fluid surrounded by a thin shell of gas surrounded by fluid (as opposed to an ordinary gas bubble which is a sphere of gas surrounded by fluid.)

They form when fluid flows turbulently into another fluid and behave in an entirely different way to ordinary bubbles. Antibubbles, for example, are negatively buoyant and so sink rather than rise.

Physicist have yet to tame the antibubble so little attention has been paid to possible applications. But one interesting possibility is that antibubbles could one day used to make drug delivery systems (pills, to you and me). The idea is to create a shell of liquid polymer around a drug and harden it with UV light.

One problem, however, is that antibubbles are unstable, and so stick around for no more than a few seconds. That makes it a little tricky to study their properties.

Now Denis Terwagne and buddies at the University of Liege have investigated how antibubbles interact with vortices and posted a video of the results (another entry in the APS gallery of fluid motion 2009). The video shows how antibubbles behave under the shearing forces that exist in vortices.

It’s not clear whether the Belgium work will help make better pills but knowing how they antibubbles behave in vortices can’t hurt, and the video is kinda cool too.

Ref: arxiv.org/abs/0910.2862: Antibubbles in a Cyclone Eyewall