**X1-014 (2003/02/12)**

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A bubble between two circular boundaries: a simple phase transition
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The shape of a bubble is investigated, the boundary of which consists of two identical circles with the same axis of symmetry. The shpae of the bubble depends only on the boundary conditions, and is obtained by minimizing the surface and is independent of the value of the surface tension. The equation of this shape is determined, and it is seen that if the ratio of the radii of the boundary circles to the distance of the centers of the circles is less than a specific value, the bubble breakes into two parts.