OBSERVATION OF BEHAVIOR OF VISCOUS FINGERING IN A HELE-SHAW CELL UNDER VARIOUS GRAVITY-LEVELS

The behavior of viscous fingering in a Hele-Shaw cell under various gr avity-levels was investigated using the drop shaft of the Japan Microg ravity Center (JAMIC) and our high-gravity generator. When silicons oi l was displaced by aqueous solution of potassium citrate through a rec tangle Hele-Shaw cell which was made of two plane-parallel acrylic pla tes, a wave of the unstable horizontal interface between the two fluid s was observed to take the form of viscous fingers. The wave number of viscous fingers decreased as the gravity level grew higher. It is con firmed that the experimental results of the wave number agreem with th e prediction by a linear stability analysis, and that gravity tends to reduce the growth rate of the finger pattern if the density of the fl uid with lower viscosity is greater than that of the fluid with higher viscosity.