Dynamics of drying in 3D porous media

TL;DR

This study investigates the drying process in 3D porous media using confocal microscopy, revealing how air invasions originate and spread due to capillary pressure, with implications for understanding porous material behavior.

Contribution

It provides detailed visualization and analysis of air invasion dynamics, demonstrating the dominance of capillary pressure and invasion percolation in drying processes of porous media.

Findings

Air invasions range from single particles to hundreds.

Air invasion patterns align with invasion percolation theory.

Capillary pressure controls the drying dynamics.

Abstract

The drying dynamics in three dimensional porous media are studied with confocal microscopy. We observe abrupt air invasions in size from single particle to hundreds of particles. We show that these result from the strong flow from menisci in large pores to menisci in small pores during drying. This flow causes air invasions to start in large menisci and subsequently spread throughout the entire system. We measure the size and structure of the air invasions and show that they are in accord with invasion percolation. By varying the particle size and contact angle we unambiguously demonstrate that capillary pressure dominates the drying process.