InterPore2026

Mathematical modelling of evaporation in capillary porous media

21 May 2026, 14:50

15m

Oral Presentation (MS06) Interfacial phenomena across scales MS06

Speaker

Ellen Luckins (University of Warwick)

Description

The evaporation of a liquid from within a porous material is a multi-phase, interfacial flow process involving coupled vapour diffusion, phase-change, and capillary flow. Mass transfer across the microscale water-air interfaces drives the macroscale porous-medium flow. Typically, different drying behaviours are seen at different stages in the drying process. When capillary forces dominate, liquid is initially drawn to the surface by capillary forces, where it evaporates at a near constant rate (stage 1); thereafter, a drying front recedes into the material, with a slower net evaporation rate (stage 2). Modelling drying porous media accurately is challenging due to the multitude of relevant spatial and temporal scales, and the large number of constitutive laws required for model closure. The motion of microscale phase interfaces results in macroscale nonlinearity of the model. I will derive simplified mathematical models for both stages of this drying process by systematically reducing an averaged continuum multi-phase flow model, using the method of matched asymptotic expansions, in the physically relevant limit of slow vapour diffusion relative to the local evaporation rate. The analysis gives insight into the subtle mechanisms that determine the overall drying rates and explains sudden changes that are observed in the evaporation dynamics. The resulting reduced models may be used to predict both the net evaporation rates and flow dynamics, and have applications in industrial drying processes, soil science, and understanding the salt-weathering of rock.