Modeling Transient Evaporation From Porous Media as a Succession of Steady-State Steps

Evaporation from bare soil surfaces is a natural flow process of global importance. During drying, significant temporal changes in flow rates occur at the soil surface, accompanied by temporal and spatial variations in the partitioning of liquid and vapor water distributions below it. We present a novel approach to modeling the transient process of evaporation from porous media as a succession of steady-state solutions. The governing mechanisms during this dynamic process are captured by accounting for the hydraulic properties of the drying medium, the characteristic features of the medium that control water flow, the atmospheric forcing, and the partitioning between the liquid and vapor phases of the water within the drying profile. We validate this simplified approach using data from a numerical model and from evaporation experiments in different soil types, under various ambient conditions. Using the model, we demonstrate the effect of soil hydraulic properties on the evaporation process. Furthermore, we use the flexibility of the model for evaluating evaporation under different initial and boundary conditions. The predictive capabilities of the proposed analytical model indicate that it is a reliable tool for representing the evaporation process.

Automated summary

The study introduces a novel model to describe the evaporation process from porous media, demonstrating its reliability and predictive capabilities through validation and experiments. The model accounts for soil hydraulic properties and can be used to analyze evaporation under different conditions.