Jan. 9, 2003, Gazette
that appear in the 2003 Art of Physics Calendar. Dr. John de
Bruyns photo of icicles on his clothesline captures a
phenomenon known as Rayleigh-Taylor instability. Dr. Yakov Afanassievs
photo captures what is known as a vortex dipole.
Physics takes on an artistic form in a 2003
calendar produced by the Canadian Association of Physicists, aptly titled
Art of Physics.
The photos have been selected from past winners of an annual photographic
contest held by the same association. Two Memorial professors photos
are featured in the calendar.
Dr. John de Bruyn, professor in the Department of Physics and Physical
Oceanography, took a photo of icicles on his clothesline. It initially
won third prize in the 1996 competition. He woke up one morning after
a night of freezing rain, and noticed that all the icicles that had frozen
on the line were equally spaced.
He took the photo, and subsequently began an investigation into the phenomenon
which is related to his primary area of research, the formation of patterns
in fluid dynamical systems. When a layer of heavy fluid lies on top of
a lighter fluid, gravity makes the heavy fluid fall down. On the other
hand, surface tension tries to stop the resultant curving. The competition
between these two forces acting on the layer of water that had formed
on the clothesline resulted in a compromise; a wave formed on the bottom
of the water layer that eventually grew into the icicles.
The spacing of the wave is determined by properties of the water (in this
case, at zero degrees). The wavelength is thus predicted to be about one
inch, the very spacing seen between the icicles on Dr. de Bruyns
clothesline. This phenomenon, known as Rayleigh-Taylor instability, is
captured in his photo.
A picture taken by Dr. Yakov Afanassiev, assistant professor in the same
department, also illustrates some interesting behaviour in a simple layer
of water. Dr. Afanassievs photo was taken in his lab, along with
the assistance of student Jennifer Wells, and won third prize in last
His photo captures what is known as a vortex dipole, a phenomenon whose
shape resembles that of a sliced mushroom. A vortex dipole is often found
in the ocean, when a force (such as wind or instable currents) is applied
to a localized area of the ocean.
To stimulate an ocean environment, Dr. Afanassiev used stratified water
in a large tank. This can be done by putting less dense water on top:
either cool water on the bottom and warm water on top, or saltwater on
the bottom and fresh water on top. He then put the tank on a rotating
platform to create the effects of the earths rotation, and added
pH indicator to the water in the tank. To make the flow visible he changed
the pH balance of the water, changing its colour. Finally, he created
the vortex dipole by simply drawing a wire through the water. The result
is a magnificently colourful photo that illustrates this physical phenomenon.
The beauty of physics is evident in these photos. According to Dr. de
Bruyn, physics is esthetically pleasing. That, combined with
the intriguing nature of the physics demonstrated, makes these photographs
both art and science.
To order an Art of Physics calendar, check out the Web site of the Canadian
Association of Physicists at www.cap.ca. To see other photos in Dr. Asfanassievs
gallery of fluid motion, please see his Web site www.physics.mun.ca/~yakov.