Abstract
This paper describes an experiment on viscous fingering instability phenomenon which yield various geometical patterns of phase boundary between two fluids with different viscosities in a porous medium. A series of evolution of patterns begins with the onset of linear instability and then leads to non-linear development of fingers, and the patterns may imply an inherent fractal structure in ultimate cases. In our study, an experiment has been carried out in a two-dimensional situation, a Hele-Shaw cell. The onset of instability was systematically searched to get a neutral curve for instability. Subsequent processes, that is the finger-shielding and finger-splitting, were also investigated with the aid of an image processing technique. Extension of the experiment to three-dimensional one is also discussed in the last part of the paper. It is found that a zero-gravity experiment is of crucial important for the realization of isotropic three-dimensional patterns in a porous medium.
