Abstract
The experiment of viscous fingering in a linear Hele-Shaw cell was carried out to investigate the relationship between the finger tip velocity and the pressure gradient. Glycerin, a Newtonian fluid, and aqueous solution of carboxymethylcellulose (CMC), non-Newtonian fluids, were used as test fluids. Air was injected into the cell filled with a test fluid. The interface of two fluids grew repeating splitting, spreading, and shielding. In glycerin, the tip velocity was proportional to the pressure gradient. In the CMC solutions, the splitting was classified into side-splitting and tip-splitting. When the side-splitting occurred, the increase rate of the tip velocity increased consistently with the pressure gradient because of the effect of shielding intensified by shear-thinning viscosity. On the other hand, the increase rate decreased when the tip-splitting occurred.
