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DIFFUSIVITY
where
is the diffusivity;
is the solubility (see “Solubility,” Section 26.4.2);
is the Soret effect factor, providing diffusion because of temperature gradient (see
below);
is the pressure stress factor, providing diffusion because of the gradient of the
equivalent pressure stress (see below);
is the normalized concentration;
c
is the concentration of the diffusing material;
is the temperature;
is the temperature at absolute zero (see below);
is the equivalent pressure stress; and
are any predefined field variables.
Input File Usage:
Abaqus/CAE Usage:
*DIFFUSIVITY, LAW=GENERAL (default)
Property module: material editor: Other→Mass Diffusion→Diffusivity:
Law: General
Fick’s law
An extended form of Fick’s law can be used as an alternative to the general chemical potential:
Input File Usage:
Abaqus/CAE Usage:
*DIFFUSIVITY, LAW=FICK
Property module: material editor: Other→Mass Diffusion→Diffusivity:
Law: Fick
Directional dependence of diffusivity
Isotropic, orthotropic, or fully anisotropic diffusivity can be defined. For non-isotropic diffusivity a local
orientation of the material directions must be specified (see “Orientations,” Section 2.2.5).
Isotropic diffusivity
For isotropic diffusivity only one value of diffusivity is needed at each concentration, temperature, and
field variable value.
Input File Usage:
Abaqus/CAE Usage:
*DIFFUSIVITY, TYPE=ISO
Property module: material editor: Other→Mass Diffusion→Diffusivity:
Type: Isotropic
26.4.1–2
Abaqus Version 6.6 ID:
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