Last modified 3 years ago Last modified on 08/04/15 10:11:22


The keyword $TORTUOSITY defines the anisotropic material behaviour, which enables the description of diffusion in porous medium. This keyword can be used in processes such as mass transport and reactive transport.


The first parameter (char) distinguishes between ISOTROPIC ORTHOTROPIC and ANISOTROPIC.

The anisotropic case (ANISOTROPIC) requires the entry of four values (double double double double) for a 2D problem, whereas for a 3D problem, totally nines values should be given.

In the following 2D example, the four values define the tortuosity for different directions. The values indicate that the tortuosity for the given material-properties-block is 1.0 in x-direction and 0.1 [-] in y-direction [-].



  1 0.4
ANISOTROPIC 1. 0 0 0.1