A mesoscopic drying model applied to the growth rings of softwood: Mesh generation and simulation results

A mesoscopic drying model that enables the drying simulation of quartersawn and flatsawn wood sections consisting of several growth rings is presented. The procedure to generate the virtual board description directly from real sample images is also described. This virtual structure accommodates the prominent sample features, including its geometrical and physical properties, together with the density and structural variation across the growth rings. We give a synopsis of the sophisticated techniques developed specifically to generate this virtual description and exhibit the final computational meshes produced by the software for quartersawn and flatsawn sections. Low temperature drying simulations are then performed for both heterogenous and homogeneous model variants using these virtual descriptions and comparisons are made of the resulting MC field evolution. A highlight of these comparisons is that the heterogeneous model captures realistic drying effects, including the fast drying of earlywood and the late removal of liquid water in latewood. In comparing the drying of quartersawn and flatsawn boards we conclude that the effect of the heterogeneous nature of the MC fields is diminished somewhat when considering the flatsawn section over the quartersawn section