Ordered packings of bubbles in columns of square cross-section

The introduction of bubbles of equal size into a confined space with dimensions comparable to the bubble diameter generally leads to the formation of ordered foam structures. We present experimental data and computer simulations of the four simplest observed structures in columns of square cross-section. The topology of the ordered structure is dependent upon the ratio of bubble size to cross-sectional area of the enclosing tube. Ordered foam structures are observed to form over a smaller range of this parameter than in the cylindrical case.