Levitating foam liquid under the spell of magnetic fields

Nov 11, 2013

Foams fascinate, partly due to their short lifespan. Foams change as fluid drains out of their structure over time. It is precisely their ephemeral nature which has, until now, prevented scientists from experimentally probing their characteristic dynamics further. Instead, foams have often been studied theoretically. Now, Nathan Isert from the University of Konstanz, Germany and colleagues, have devised a method of keeping foams in shape using a magnet, which allows their dynamics to be investigated experimentally, as recently described in European Physical Journal E.

To find a way around the issue of drainage, the authors used the so-called diamagnetic levitation technique. This approach exploits the fact that water—which is one of the main components of foams—has a characteristic called diamagnetism. This means that water molecules can become magnetised in the opposite direction to an applied . Hence, a strong magnetic field can be used to levitate the water in a foam within the bore of a magnet of 18 Tesla in strength. This prevents drainage and allows a very high level of to be maintained in the foam.

Isert and colleagues have used this approach to study the coarsening behaviour of foams with greatly varying liquid fractions. As a result, they experimentally verified the decades-old theoretical predictions for the growth in bubble size for dry as well as liquid foams. They found that for a liquid fraction of about 30%—which corresponds to a foam with bubbles which start to no longer touch—the gas exchange between bubbles and the corresponding growth laws changes.

Next, they will study how the local microscopic dynamics influences the foam's global dynamics. This is of particular interest when the transitions from a liquid to a solid form.

Explore further: Thermoelectric power plants could offer economically competitive renewable energy

More information: N. Isert et al. (2013), Coarsening dynamics of three-dimensional levitated foams: from wet to dry, European Physical Journal E 36: 116, DOI: 10.1140/epje/i2013-13116-x

Related Stories

Uncovering liquid foam's bubbly acoustics

Oct 17, 2013

Liquid foams fascinate toddlers singing in a bubble bath. Physicists, too, have an interest in their acoustical properties. Borrowing from both porous material and foam science, Juliette Pierre from the Paris Diderot University, ...

Air bubbles could be the secret to artificial skin

Jun 07, 2013

(Phys.org) —Using foam substrates, EPFL scientists were able to make a flexible electronic circuit board. This discovery could lead to the creation of deformable and stretchable circuits.

Space for dessert?

Jul 16, 2012

(Phys.org) -- All chefs know that preparing the perfect chocolate mousse is one part science and one part art. ESA’s microgravity research is helping the food industry understand the science behind the ...

Non-harmful flame retardants with no additional cost

Jul 23, 2013

Flame retardants are often extremely harmful to health. Despite this, they are found in many types of synthetic materials which would otherwise ignite quickly. Empa researchers have now succeeded in producing non-harmful ...

Recommended for you

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.