Evaporation in capillary porous media at the perfect piston-like invasion limit: Evidence of non-local equilibrium effects

Alirez Attari Moghaddam (1) , Marc Prat (2) , Evangelos Tsotsas (1) , Abdolreza Kharaghani (1)

1 OVGU - Otto-von-Guericke-Universität Magdeburg = Otto-von-Guericke University [Magdeburg]
2 IMFT - Institut de mécanique des fluides de Toulouse

The classical continuum modeling of evaporation in capillary porous media is revisited from pore network simulations of the evaporation process. The computed moisture diffusivity is characterized by a minimum corresponding to the transition between liquid and vapor transport mechanisms confirming previous interpretations. Also the study suggests an explanation for the scattering generally observed in the moisture diffusivity obtained from experimental data. The pore network simulations indicate a noticeable nonlocal equilibrium effect leading to a new interpretation of the vapor pressure‐saturation relationship classically introduced to obtain the one‐equation continuum model of evaporation. The latter should not be understood as a desorption isotherm as classically considered but rather as a signature of a nonlocal equilibrium effect. The main outcome of this study is therefore that nonlocal equilibrium two‐equation model must be considered for improving the continuum modeling of evaporation.

Mots clés: Slow evaporation; Nonlocal equilibrium; Transport coefficients; Pore network simulations; continuous model

Domaines: Mécanique des fluides [physics.class-ph]

Alirez Attari Moghaddam, Marc Prat, Evangelos Tsotsas, Abdolreza Kharaghani. Evaporation in capillary porous media at the perfect piston-like invasion limit: Evidence of non-local equilibrium effects. Water Resources Research, 2017, 53 (12), pp.10433-10449. ⟨10.1002/2017WR021162⟩. ⟨hal-01795775⟩