Finite Changes of Bound Water Moisture Content in a Given Volume of Beech Wood

The undesired wood instabilities are connected with the changes of bound water moisture content. The rates of finite changes of bound water moisture content in a given volume of wood were determined in the frame of the specimen dimensions. The derivation is based on the 1st Fick’s law and diffusion equation solution in three dimensions. The inverse solution of diffusion equation provided the diffusion coefficients in the principal anatomical directions. Beech wood was tested. The nonlinear regression is involved in the inverse solution. Therefore, the starting values of diffusion coefficients were computed according to the proposed three dimensional square root scheme. The evaluation of data revealed the random character of transport characteristics. The sufficient condition for the slowest finite change of ound water moisture content in a given volume of beech wood is the ratio 8.7:1.5:1.0 of dimensions in longitudinal, radial and tangential directions.