Particle-induced viscous fingering

To isolate the coupling between fluid-fluid interfaces and suspended particles, we experimentally demonstrated that the suspension-air interface becomes unstable and leads to the formation of particle clusters, when a particle-oil mixture radially displaces air inside a Hele-Shaw cell. Note that the oil-air interface in the same flow configuration is stable without the presence of particles. This particle-induced viscous fingering arises from the accumulation of particles on the advancing oil-air interface, which generates the unstable viscosity gradient inside the suspension. We employed the continuum model to verify that the particles migrate towards the centerline (known as shear-induced migration) and, on average, move faster than the mixture, which causes particle accumulation on the interface. We also performed the stability analysis to predict the most unstable wavenumber and extended this study to bi-disperse suspensions and inward viscous fingering upon drainage. 

A. Hooshanginejad*, B. Druecke* and S. Lee, “Stability analysis of particle band on the fluid-fluid interface,” Journal of Fluid Mechanics (2019) 869, R2
https://doi.org/10.1017/jfm.2019.239

F. Xu* and S. Lee, “The enhancement of viscous fingering with bidisperse particle suspension,” Journal of Fluid Mechanics (2019) 860, 487-509

R. Luo*, Y. Chen* and S. Lee, “Particle-induced viscous fingering: Review and outlook,” Physical Review Fluids (2018) 3, 110502 (Invited paper associated with the 70th Annual Meeting of the APS Division of Fluid Dynamics invited talks)
https://doi.org/10.1103/PhysRevFluids.3.110502

J. Kim*, F. Xu* and S. Lee, “Formation and destabilization of the particle band on the fluid-fluid interface,” Physical Review Letters (2017) 94, 023112 (selected as a Physical Review Letters Editors’ Suggestion)
https://doi.org/10.1103/PhysRevLett.118.074501

F. Xu*,3, J. Kim*,3 & S. Lee, “Particle-induced viscous fingering,” Journal of Non-Newtonian Fluid Mechanics, (2016) 238, 92
3co-lead authors
https://doi.org/10.1016/j.jnnfm.2016.06.014

 

As the extension of particle-induced viscous fingering, we are delving into miscible fingering without the influence of surface tension, by injecting pure oil into the mixture of the same oil and non-colloidal particles inside a Hele-Shaw cell. The experiments show qualitatively similar trends as pure liquids in the continuum limit but show clear deviations, as the channel confinement is increased. Hence, we aim to uncover how the discrete nature of particles may fundamentally change miscible fingering, by systematically increasing the channel confinement. 

R. Luo*, Y. Chen* and S. Lee, “Particle-induced miscible fingering: Continuum limit,” Physical Review Fluids (2020) 5, 094301
https://doi.org/10.1103/PhysRevFluids.5.094301