A novel methodology to study effects of the electric field on shape and surface tension of drops in microgravity

The behavior of liquid drops and bubbles in an electric field is of importance both for improving existing and developing new technologies on the ground and in space. Examples are electrostatic spraying, ink jet printing, electro wetting, physical and chemical separations and alloy research in space. Of particular interest is the effect of electric fields on shape and surface tension of drops and bubbles. Because of mathematical limitations as well as for practical reasons we have been developing a tool for studying these two quantities under microgravity conditions. The new methodology, called Axisymmetric Drop Shape Analysis - Electric Field (ADSA- EF), generates numerical drop profiles in the electric field, for a given surface tension. Then, it calculates the surface tension by matching the theoretical profiles with the shape of the experimental drops. The new methodology predicts the shape of conducting drops in the electric field with high accuracy. Preliminary ground-based experiments suggest that the surface tension of liquids is changed by one or two percent in the electric field. The magnitude of this change depends on the polarity of the liquid. More definitive results for drops as well as the effect of the polarity of the electric field will be presented at the conference. However, ultimate validation requires experimental work under reduced and/or microgravity conditions. Finally, under such conditions, because of the absence of convection, the developed methodology can be a valuable tool to study electric field driven adsorption and diffusion in two component liquids.