Free Water migration within Unsaturated Wood
PI : Romain Rémond (EA 4370 Laboratoire d’Étude et de Recherche sur le Matériau Bois – LERMAB)
Collaborations : J. Colin (LGPM, EA4038-CentraleSupelec), P. Perré (Laboratoire de Génie des Procédés et Matériaux, LGPM), P. Lu (Chaire de Biotechnologie de CentraleSupelec-Pomacle), E. Mougel (Laboratoire d’Étude et de Recherche sur le Matériau Bois, LERMAB)
________________________________________________
Context — The prediction of liquid water migration within wood remains a challenge for its applications in construction, for its preservation, as for the evaluation of using properties in services. When two fluid phases exist in porous media (liquid-gaseous phases), the macroscopic formulation of the mass transfers uses the generalized Darcy’s law in which the phenomenological coefficient is the product of an intrinsic permeability by a function of the saturation state, called relative permeability. The determination of this function remains complex and very few results are available in the literature. Yet, it is a key parameter for calculating the apparent velocity of the liquid through the wood.
Objectives — This work proposes to develop a reliable method (inverse approach) to measure the expression of liquid relative permeability for spruce.
Approaches — The method consists of three complementary parts:
- experimental determination of moisture content profiles during water absorption tests by X-ray absorptiometry,
- numerical simulation of the moisture migration within the wood sample using the actual conditions (the computational model TransPore, developed by P. Perré (LGPM, ECP) is used),
- identification of the relative permeability expression using an inverse method that minimizes the objective function based on the difference between experimental and theoretical moisture content profiles at different times.
Expected results and impacts — This new and reliable approach to measure the liquid relative permeability will improve the predictions quality of computational model of heat and mass transfer for wood. It could allow progresses in a wide field of thematic: evident in the wood drying, but also in the hygrothermal transfer within building wall, for the prediction of fungal development and growth, etc.
