The electrohydrodynamic stability of a leaky dielectric liquid bridge in an axial electric field with zero Bond number

A liquid bridge is a column of fluid pinned at either end by rigid plates. Provided the Bond number is small, a bridge is stable when its length is less than its circumference. The equilibrium shape is cylindrical. In this study, the Bond number is kept small by performing the experiments in microgravity aboard the space shuttle during the Life and Microgravity Spacelab mission (STS-78). Some of the microgravity experiments duplicated previous terrestrial experiment by immersing some of the bridges in an isopycnic liquid bath. Here we study the electric fields necessary for stability for fluids having a range of physical properties using DC and AC fields. The electrical conductivity of the bridge fluid is modified using an organic electrolyte.;In the laboratory, bridges of castor oil are formed in a matched density silicone oilbath. In microgravity experiments, the matched density outer liquid can be replaced by a gas having a high dielectric strength. This simplifies matters considerably. In preparation for the space shuttle flight experiment, preliminary trials were carried out aboard aircraft flying parabolic arcs to produce low acceleration environments. Since the duration of the low gravity environment in an airplane is brief, the apparatus is automated and computer controlled.;Results from the microgravity experiments aboard the space shuttle flight where the bridge is suspended in a liquid bath match those from terrestrial experiments with the same liquids. When the outer liquid is replaced with a gas the behavior is quite different and much larger fields are required to stabilize the bridge. To complement our experimental results, a linearized stability analysis has been developed for a single-phase bridge. The bridge is treated as a highly viscous, leaky dielectric liquid. The Papkovich-Fadle functions are used to describe the hydrodynamics. Perfect dielectric behavior emerges as a special case. Agreement between theory and experiment is tenuous unless surface conductivity--not accounted for in Taylor's leaky dielectric model--is included. The development of the parabolic flight apparatus, the space shuttle experimental results, the stability model results, and comparisons between theory and experiment are presented.