The Penman-Millington-Quirk (PMQ) Vapour diffusion model.

The vapour diffusion can be described by [28], [29],

\[
D_v=D_0 \left(\frac{T}{273.15}\right)^{n}
D_{vr},
\]

where \(D_{0}\) is the base diffusion coefficient with default value \(2.16\cdot 10^{-5}\) \({\text m}^2
\text{Pa}/(\text{s}\text{K}^{n})\), \(n\) is the exponent with default value 1.8, \(D_{vr}\) is the the relative diffusion coefficient, and \(T\) is the temperature.

The Penmanâ€“Millingtonâ€“Quirk (PMQ) model [28] is given as

\[
D_{vr}=0.66 \phi \left(\frac{\kappa}{\phi}\right)^{\frac{12-m}{3}},
\]

where \(\phi\) is the total porosity, \(\kappa\) is the air filled porosity, and \(m\) is a fitting parameter. The air filled porosity is defined as \( \kappa = \phi-\theta = \phi -S_L \phi \) with \(\theta\) the liquid content, and \(S_L\) the liquid saturation.

According to the study presented in [28], \(m=6\) is the best fitting parameter for the sieved, repacked soils that the authors tested. Therefore, \(m=6\) is used in the implementation, which gives

\[
D_{vr}=0.66 \phi (1 - S_L )^2.
\]

Note: In order to maintain consistency with the implementation of the computations of other vapor-related parameters, \( \phi (1 - S_L )\) is removed from the implementation for this class and is multiplied back in the local assembler.

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Child parameters, attributes and cases

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Additional info

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From MaterialLib/MPL/Properties/VapourDiffusion/CreateVapourDiffusionPMQ.cpp line 39

- This is a required parameter.
- Expanded tag path: NONEXISTENT.property.VapourDiffusionPMQ
- Go to source code: → ogs/ogs/master

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Used in the following test data files

Used in no end-to-end test cases.