|
Experimental
Procedure
We
refer to the fine polystyrene beads placed in the polyacrylate container as a
granular bed. Into this granular bed was placed a large particle called an
"intruder." For the experiments carried out, different intruder
particles were used, all fabricated from brass (density = 8350 kg/m3)
or polyvinyl chloride (PVC) (density = 1380 kg/m3). Each intruder was
disk-shaped with an outer diameter D. In order to vary the intruder
density, holes of diameter d were drilled in the center of some disks
resulting in an annular structure; see the picture below. All intruders
were 4.35 mm thick, slightly less than the 4.5 mm depth of polyacrylate
container.
Sample
brass intruders used in the experiments carried out.
The
motion of the intruder in the granular bed was studied from video images made
using a Panasonic DSP color camera, which was placed in front of the granular
bed. Movies were made with the camera at a rate of 25 frames per second, and
were stored on a personal computer (PC).
For
a set amplitude of vibration, the frequency was varied, and the rise (Brazil Nut
Effect) or sink (Reverse Brazil Nut Effect) of the intruder in the granular bed
was recorded.
___________________________________________________________________________
In
addition to the quantitative experiments described above, qualitative experiments
of the Brazil Nut Effect were also carried out. These experiments involved the
use of (1) a mixture of nuts and (2) a mixture of fine polystyrene particles and
silica pebbles.
Sample
movies of both the quantitative and qualitative experiments are presented next.
Next:
Sample 2D Movies
|
