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Figure 1: Images of a 12 mm inner diameter vertical tube of emulsion evolving over time. Visible intensity steps in the rightmost photographs indicate steps in decane droplet concentration, with brighter regions having higher concentration. From left to right, photos were taken after 0, 51, 73, 100, 137 and 175 hours of creaming.

Figure 2: Positions of the strata boundaries for the tube in Fig. 1 as a function of creaming time.

Figure 3: Direct visualization of convective flow in a stratified suspension. Top: Three photographs following the time evolution of a line of dye in a 22 mm inner diameter tube of stratified emulsion. A small heat source, located to the right in the plane of the photograph, was used to set up a constant 10 mK temperature difference across the tube. The leftmost photograph shows a weighted projectile impregnated with nigrosin dye falling down the centerline of the tube, leaving a dye stream in its wake. The other two photographs show the system 5 and 35 seconds later. Deformation of the dye line clearly indicates small fluid flows in the suspension with high gradients precisely at the boundaries between the strata, visible as the faint banding in the tube. Simultaneous observations from the side showed no deformation out of the plane of the photograph. Bottom: The horizontal flow velocity along the tube's centerline as measured from the photographs above.

David G. Grier
Sat Jun 8 10:35:47 CDT 1996