An extension of the capillary and thin film flow model for predicting the hydraulic conductivity of air‐free frozen porous media

Abstract

Hydraulic conductivity of frozen air‐free porous media is a rather elusive property that remains largely undefined in much of the literature. According to modern science, water transport in frozen porous media occurs mostly in ice‐free capillaries at temperatures close to the freezing point of pure water and through a thin liquid interlayer, between solid particle and ice, at lower temperatures. In accordance with this understanding, this paper extends the capabilities of an existing capillary and thin film flow model to include the prediction of hydraulic conductivity in frozen air‐free porous media. As such, hydraulic conductivity of the frozen porous media is predicted with a simple capillary bundle model as well as with a new hydrodynamic model of thin interlayer flow in which film thickness is controlled by both London‐van der Waals and ionic‐electrostatic forces. As with other predictive models of hydraulic conductivity, most model parameters are derived from more easily measured water content data in either ice‐free (water retention function) or air‐free (water freezing function) porous media. Model results showed very good agreement with observed values of hydraulic conductivity taken at thermal equilibrium, and illustrated the importance of thin interlayer flow at lower temperatures.