| dc.description.abstract | Viscos fingering is a fluid interface instability phenomenon. It occurs when a less viscous fluid displaces another relatively more viscous fluid. For this problem, most researchers have used Hele-Shaw cells to study the fingering effects. Previous literature has shown that a linearly time-dependent injection flow rate can suppress viscous fingering in a drainage flow. However, it is not clear whether this is still true for other situations, like an imbibition displacement and extraction flow. In this study we used a radial Hele-Shaw cell, in which less viscous fluids were used to displace more viscous fluids to experimentally investigate how viscous fingering may evolve for different wettability with time-dependent flow rates. Effects of dimensionless final time, and capillary number were considered too. The results showed that the linearly time-dependent injection flow rate could more effectively suppress viscous fingering in drainage displacement than in imbibition displacement. No matter how capillary number, dimensionless final time and wettability change, the linear injection rate can still suppress the fingering instability. However, for the extraction case, the linearly time-dependent flow rate could not always suppress the fingering instability. The linearly time-dependent flow rate could suppress the fingering instability only for lower capillary numbers. For the dimensionless final time, there might exist an appropriate range, in which the linearly time-dependent flow rate suppress the fingering instability. For wettability effect, the wetting film impairs the suppression effect of the linearly time-dependent flow rate on viscous fingering. Based on the finding, the linearly time-dependent flow rate should be adjusted taken into account the wetting film. | en_US |