ISSN Online: 2377-424X
ISBN Print: 978-1-56700-421-2
International Heat Transfer Conference 15
Bubble Growth in Microgravity Under the Action of Electric Forces: Experiments and Numerical Simulation
Abstract
The classical problem of growth and detachment of a bubble from an orifice is revisited in this study, to
achieve a better comprehension of the role played by gravity and/or an additional electrostatic field on the
bubble, with the aim to develop efficient and adequate numerical tools including the action of electric force.
In particular, numerical simulation of the bubble growth was performed and compared with the experimental
results obtained in a parabolic flight campaign (ESA-PF58). The experimental apparatus consisted in an
orifice (0.40 mm in diameter) drilled in a flat stainless steel plate submerged in the test fluid (FC-72).
Nitrogen was injected in the orifice by means of a flow controller. An electric potential up to 25 kV
could be applied to a washer-shaped electrode located 6 mm above the plate and centered with the orifice
axis. Data were acquired via a high speed video camera, equipped with a microscopic lens. Bubble images
were digitized and processed via dedicated software, implemented in Matlab. Numerical simulations were
carried out using an interface tracking method. The interface tracking is based on a level set method with a
volume correction scheme. The ghost fluid method is used to evaluate surface tension force. The electric
field is obtained by solving the equation of Gauss' law using a standard difference method. Two-dimensional
cylindrical coordinate systems were used. Fairly good agreement was obtained for bubble shape in
microgravity. Furthermore, the study of local bubble curvature allowed comparison with theoretical model of
capillary and electric pressure at the interface.