Euler Characteristic of Fluid in Porous Media during Drying Process

Abstract:

Drying in porous media is a complex process. It affected by the atmospheric condition (humidity, temperature, wind velocity, water vapor pressure), characteristic of the porous medium (grain size distribution, pore size), and the rate of drying fluid flow. The convoluted and high dimensional process makes it difficult to upscale the fluid distribution from a small-scale experiment or model. Recently, the study of fluid topology has provided an alternative point of view through this problem. The Euler characteristic quantifies the connectedness of fluid instead of the bulk volume, which may be more relevant to the rate of fluid flow. The study aims to investigate the continuous fluid topology change during the drying process and connect it with the physical mechanisms. Two different drying mechanisms are examined by the 2D micromodel, air injection and evaporation. The result shows that the corner film may be critical to distinguish the two different drying patterns. Furthermore, a 3D sand packing evaporation experiment is conducted. Comparing the fluid topology in 3D sand packing with the 2D micromodel, the trends of non-wetting fluid Euler characteristics are similar. However, the wetting fluid Euler characteristics have almost opposite behavior, which may indicate that the results in 2D micromodel cannot be replicated to 3D the condition.