Comparison of viscous fingering patterns in polymer and newtonian solutions

✍ Scribed by Masami Kawaguchi; Kyoko Makino; Tadaya Kato

• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 949 KB
• Volume: 105
• Category: Article
• ISSN: 0167-2789
• DOI: 10.1016/s0167-2789(96)00291-6

✦ Synopsis

Viscous fingering patterns of aqueous glycerol and hydroxypropyl methyl cellulose (HPMC) solutions pushed by air in the Hele-Shaw cell were observed as a function of isopropyl alcohol. An increase in isopropyl alcohol led to a decrease in surface tension as well as an increase in viscosity of the respective solutions. For the glycerol solutions, namely Newtonian fluids, only the tip splitting pattern was observed, where the fingers were indeed narrower and the number of the fingers increased with increasing isopropyl alcohol content. These morphological changes in the patterns for the glycerol solutions were in agreement with the computer simulations based on the diffusion limited aggregation model. The finger tip velocity is proportional to the ratio of the injection pressure to viscosity according to Darcy's law prediction. In contrast, for HPMC solutions, which show shear-thinning, highly branched pattern only appeared when the injection pressure was changed. When isopropyl alcohol was added to HPMC solutions, a morphological transition from highly branched pattern to tip splitting one was observed. The transition in the pattern would be related to changes in both elastic properties and surface tension. The finger tip velocity of HPMC solutions is scaled with 1.5 power of the ratio of injection pressure to viscosity.