Heat and mass transport at air-material interfaces

Convective drying | Drying modeling | Evapotranspiration

Convective drying

Mass transfer from porous materials depends on the boundary conditions, i.e. air flow, velocity and turbulent kinetic energy (TKE), relative humidity and temperature. We use neutron imaging to study drying under controlled air flow conditions starting from fully wet conditions. We study the drying processes within a groove of 2 cm x 2 cm in a clay brick with neutron imaging in a small wind tunnel.

Moisture content distribution in brick during drying

PIV measurements of air flow in groove

Drying modeling

The drying of porous materials involves the modeling of transport in both the air and the porous material, or conjugate modeling. With conjugate modeling, the spatial and temporal variability of convective transfer coefficients can be unveiled.
Conjugate modeling avoids the use of simplified, a-priori determined convective transfer coefficients. It is inherently more accurate and provides customized heat and mass exchange predictions at the air-material interfaces.

Drying fronts and boundary layer for a flat plate.

Spatial and temporal variation of convective mass
transfer coefficient from conjugate modeling.


Evapotranspiration involves transpiration via microscopic pores in the leaf surface, called stomata, and evaporation of droplets on the surface. Numerical analysis of evapotranspiration requires cross-scale numerical modelling from macro- down to the microscale.

2D isocontours in air above leaf

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