Drying of porous materials at pore scale using lattice Boltzmann and pore network models

Abstract

Drying at macroscale shows a first drying period with constant drying rate followed by second drying period showing a receding moisture front, phenomena that can be tailored upon need. In order to study the drying of materials, we present a new hybrid computational method, where the dynamics of the liquid-vapor interfaces is modelled by lattice Boltzmann modelling (LBM) in the two-phase pores, while the single-phase flow in the pores filled solely by vapor or liquid is solved by pore network model (PNM). This hybrid method is validated by comparison with reference full LBM simulations. The hybrid method combines the advantages of both methods, i.e., accuracy and computational efficiency. LBM and the hybrid LBM-PNM method are used to study the drying of porous media at pore scale. We analyse two different pore structures and consider how capillary pumping effect can maximize the drying rate. Finally, we indicate how optimized drying rates are relevant when designing facade or pavement solutions that can mitigate higher surface temperatures in urban environments by evaporative cooling.