InterPore2026

Labyrinth patterns in a 2D cell under gravity effect

19 May 2026, 09:50

1h 30m

Poster Presentation (MS05) Physics of multiphase flow in diverse porous media Poster

Speaker

Maud Viallet

Description

Multiphase frictional flows, involving the transport of solid grains by fluids in confined environments, are common in both natural and industrial contexts such as mudflows, volcanic intrusions, and soil remediation. Despite their prevalence and significant environmental and economic impact, these systems are still not well understood.
These flows typically involve three phases: two mobile fluids and a porous solid matrix. When the solid phase is soft or fragile, as in granular packings, fluid motion can mobilize the grains, leading to a three-phase system where granular friction and jamming play a key mechanical role. Such systems are referred to as multiphase frictional flows.
A key focus of this work is the influence of gravity on flow patterns in these systems. This effect is commonly described using the Bond number, which represents the ratio of gravitational to capillary forces. Positive Bond numbers correspond to gravitationally unstable configurations, while negative values indicate stabilization of the fluid–fluid interface. Here, we study the unstable case, in which a lighter fluid is injected from below into a denser liquid saturating a granular medium.
The experiments are conducted in a Hele–Shaw cell composed of two circular glass plates separated by a narrow gap. The cell is filled with a water–glycerol mixture and partially packed with glass beads, creating a mobile porous medium. Air is injected at a constant, low flow rate through a central inlet. Under these conditions, viscous effects are negligible, allowing capillary and gravitational forces to dominate the dynamics.
Tilting the cell changes the relative importance of gravity and capillarity, thereby modifying the Bond number. This has a strong impact on the invasion patterns: as the tilt increases, the resulting frictional fingers become more directional and less branched. Gravity therefore introduces a clear bias in the growth of the flow structures, which we propose to quantify using the Bond number.