Water movement on the convex surfaces of porous media under microgravity

Pore-Scale Wetting Process of Capillary-Driven Flow in Unsaturated Porous Media under Micro- and Earth-Gravities

“…A few theories have been proposed to explain the gravity dependencies of capillary flows. For example, Jones and Or [8] hypothesized that "air entrapment" and "particle separation" contributed to smaller flux densities under microgravity than under 1 G. When the wetting front moved to the pore body from the pore neck in massive porous media [9] (Figure 1a) or glass tube [10] (Figure 1b), "interruption on widening void space" in the wetting front was observed. Or et al [11] noted that when fine and coarse beads were packed side by side, water exclusively flowed in the fine beads.…”

“…Therefore, studying pore-scale flow is essential for elucidating the gravity dependency of capillary-driven flow in unsaturated porous media. Two types of "interruption on widening void space" under microgravity: (a) the interruption on the widening on the single porous particle [9] and (b) the interruption on the widening of capillary (Maruo et al [10] for capillary tubes; Or et al [11] for porous media).…”

“…Figure 1.Two types of "interruption on widening void space" under microgravity: (a) the interruption on the widening on the single porous particle[9] and (b) the interruption on the widening of capillary (Maruo et al[10] for capillary tubes; Or et al[11] for porous media).…”