Anisotropic Approach to Control Viscous Fingering Pattern Generated in Lifting Plate Hele-Shaw Cell

Stability is one of the important aspects of life, our everyday systems — the permanence of things. When this stability gets disturbed, instability is produced. Sometimes this instability is desirable, and sometimes not. In the crude oil extraction process, fluid instability is observed. Saffman and Taylor explored the concept of the Hele-Shaw cell to study these instabilities. The Hele-Shaw cell involves a high viscous fluid sandwiched between two parallel plates, and the low viscosity fluid enters from the periphery. Insertion of low viscous fluid into a high viscous fluid generates a pattern that is a resemblance to a finger. This phenomenon is called viscous fingering. In this paper, the authors control the instabilities and mimic patterns available in nature. These instabilities can be controlled by controlling one of the fluids in the cell. Here authors control the low viscous fluid (air) by providing anisotropies. Anisotropy means providing holes and slots on any plate of the cell. This anisotropy guides air to interact with high viscous fluid at some desired location. The authors further studied the effect of size, position, the orientation of these holes and slots on the viscous fingering exhaustively.