Figure. Solution Systems and Displacement Experiments. (IMAGE)
Caption
(a) Phase diagram of PEG 8000-Na2SO4-water system and solution systems used in the present study. Region I is a one-phase region and region II is a two-phase region. When the concentration is set in red triangle, the solution is separated into two phases, phase L and phase H. The solution compositions used in the immiscible, fully miscible, and partially miscible systems are indicated by red, black, and green circles, respectively. (b) When a more viscous liquid is injected from a single point into a Hele-Shaw cell (a gap between two parallel flat plates with a very small distance b (= 0.3 mm)) filled with a less viscous liquid, their interface becomes hydrodynamically stable and spreads out in a circle. (c) Hydrodynamically stable displacement in the immiscible, fully miscible, and partially miscible systems for a given flow rate. The pictures are taken when the longest radius of the displacement pattern is 42 mm and the injection time is shown at the lower right corner of each picture. The circles in the figure correspond to the circles in the phase diagram of (a). That is, in the immiscible system, the compositions of the more viscous solution and the less viscous solution are represented by open-circle in red and solid-circle in red. In the fully miscible system, the composition of the more viscous solution, of the less-viscous, and of their mixed solution are represented by open-circle in black, solid-circle in black, and star in black. In the partially miscible system, they are represented by open-circle in black, solid-circle in black, and star in green.
Credit
Yuichiro Nagatsu/ TUAT
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