Morphological transitions of capillary rise in a bundle of two and three solid parallel cylinders

Morphological transitions here refer to the liquid-body instability of capillary rise as the spacing among cylinders changes and are studied in this paper with both theoretical analysis and experimental verifications for systems composed of two and three equidistant and parallel cylinders systems. The theory predicts cross-sectional shapes of the bounded liquid body in a bundle of cylinders, when gravity is neglected, as a function of the cylinder–cylinder separation, contact angle and the Harkinson/spreading parameter. All these morphological transitions in turn reveal the hysteresis mechanisms in the processes.