Viscously Stable Frictional Fingers in Hele-Shaw Cells

Explore the fascinating world of fluid dynamics in a lecture on viscously stable frictional fingers presented by Prof. Bjørnar Sandnes from Swansea University, UK. Delve into the complex interactions between invading fluids and granular materials in a Hele-Shaw cell, examining how the competition between friction and capillarity leads to the formation of finger-like patterns. Discover how increasing viscosity or injection rate amplifies the role of viscous forces in pattern formation. Investigate the unique scenario of injecting a high viscosity fluid into a bed of grains submerged in a low viscosity fluid, and observe the transition from single active fingers to multiple fingers and finally to a fully compact "spoke" pattern. Gain insights into the bulldozing frictional instability and its effects on fluid flow through granular media.