Diffusivity #

The diffusivity calculation can give you

1. effective diffusivity of the system
2. concentration profile
3. molar flux density

Solved equation Method descriptions #

$\nabla \cdot j = 0$, where $j = D \nabla c H$

• j Molar flux density
• D Diffusivity
• c Concentration

Input options #

The following options are needed for the diffusivity calculation.

• input->system The choice of calculation system must be diffusion
• input->external->concentrationGradient External applied concentration gradient $(mol/m^4)$, if you want to calculate the concentration distribution within the composite
  • x Applied concentration gradient along x
  • y Applied concentration gradient along y
  • z Applied concentration gradient along z
• input->solver->ref A property tensor for the reference phase called diffusivity$(m^2/s)$ is needed. Tensor definition is explained [here]

<system>
    <type>diffusion</type>
    <external>
        <concentrationGradient>
            <x>0</x>
            <y>0</y>
            <z>2e7</z>
        </concentrationGradient>
    </external>
    <solver>
        <ref>
            <name>diffusivity</name>
            <rank>2</rank>
            <pointGroup>custom</pointGroup>
            <component>
                <value>100</value>
                <index>11</index>
                <index>22</index>
                <index>33</index>
            </component>
        </ref>
    </solver>
</system>

Output files #

There are a total of 4 possible output files for the dielectric calculation

1. effDiffusivity.dat
2. avMolarFlux.dat
3. concentr.00000000.dat
4. concGrad.00000000.dat
5. molFlux.00000000.dat