Observations of Surfactant Driven Instability in a Hele-Shaw Cell

Abstract

A surfactant driven instability is observed in the air-liquid interface of an aqueous surfactant solution moving inside a prewetted glass Hele-Shaw cell with a gap width of 300 mm when the viscous surfactant solution is pushing on the less viscous air. This is the reverse direction of the wellknown Saffman-Taylor instability. The fluctuations produced by the instability will develop into a steady state cellular pattern with the sharp fingers pointing in the opposite direction of the motion of the interface. This instability occurs only when the velocity of the interface exceeds a critical value which depends on the geometry of the cell and the wetting layer in the air side of the interface.[S0031-9007(97)04711-X]

Inverse Saffman-Taylor Experiments with Particles Lead to Capillarity Driven Fingering Instabilities

“…This instability relies on the integration of partially wettable particles to the meniscus driven by the minimization of interfacial energy. A reverse Saffman-Taylor instability in the presence of surfactants has been previously reported in the literature by Chan et al [11] and then by Fernandez et al [12], but, in contrast to these studies, the fingers observed in our studies with particles are not limited in depth.…”

Interfacial elastic fingering in Hele-Shaw cells: A weakly nonlinear study

“…The development of the reversed viscous fingering instability has been investigated both theoretically and experimentally by considering the addition of surfactants to the moving interface, or to the Hele-Shaw cell plates [14][15][16][17][18][19][20]. The presence of the surfactant may cause the surface tension to vary along * jme@df.ufpe.br the fluid-fluid boundary, facilitating the occurrence of local disturbances.…”

On a new surfactant-driven fingering phenomenon in a Hele-Shaw cell

“…In the above example, like many others, surfactant-generated Marangoni effects just modify the existing solution to leading order, but do not introduce any new fundamental instabilities. The experiments conducted by Chan & Liang (1997), however, have demonstrated that surface-active substances crucially influence the Saffman-Taylor phenomenon and even reverse its stability characteristics. Figure 1 gives a diagram of the experiment: a Hele-Shaw cell is dipped into a surfactant solution at speed V .…”