Our experimental setup consists of a plexiglas hollow cylinder 5 inches in diameter and 2 feet long with Plexiglas plates bolted onto either end. A bolt is attached to the outside of each plate, coaxial to the cylinder, which rests on a ball bearing mount. One of these bolts has an additional flange at its other end connected by a belt to a 1/17 hp motor. For each run the cylinder is one third filled with a 50/50 binary mixture of either glass beads of two different diameters, each approximately uniform in size, or of glass beads of one diameter and sand. The glass beads ranged in diameter from about 0.7 to 4.8 mm, and the sand was irregularly shaped with average distance across each grain of about .4 mm. The smaller beads are dyed black improve the contrast in the photographs, though the phenomenon is not affected by the dye. The cylinder was leveled using shims, though again the results did not depend on precise leveling. The image shows an initially homogeneous mixture of rice and split peas. After rotation, distinct segregated bands form.
|Reversible axial segregation results|
|Dynamic angle of repose theory for size segregation|
|Bulk segregation measured by Magnetic Resonance Imaging|
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