Zero-gravity liquid-vapor interfaces in circular cylinders

The zero-gravity problems of a liquid volume sealing a circular tube of gas and a gaseous volume in a circular tube of liquid both involve one phase obstructing another. The two problems differ only in contact angle. From pulmonary research there is a history of axisymmetric analyses for liquid droplets in circular tubes of gas. These analyses consider only axisymmetric solutions-an annulus and an axisymmetric plug. Only recently have nonsymmetric solutions for nonzero contact angle wetting liquids (0 degrees-90 degrees contact angle) been realized by the authors with the use of the Surface Evolver code. Similar to the problem of droplets in a gas filled tube, a bubble in a liquid-filled tube is of interest to the commercial satellite industry and in vascular physiology. Further analysis by the authors now fills in the other half of contact angle range, i.e., either a nonwetting liquid in a tube of gas (contact angles of 90 degrees-180 degrees), or equivalently, a gaseous bubble in a liquid that wets the tube wall. Conditions for the existence and stability of solutions of three topologies are examined. (c) 2006 American Institute of Physics.