OGS

A model for water vapour density in the unsaturated porous media.
The water vapour density is given by
\[ \rho_v = h\, \rho_{vS}, \]
where \(h\) is the relative humidity according to
\[ h=\exp({\frac{p}{\rho_w R T}}), \]
with \(R\) the specific gas constant for water vapour, and \(\rho_{vS}\), is the saturated vapour density given by
\[ \rho_{vS}=10^{3}\, \exp({19.8194975.9/T}). \]
The specific gas constant for water vapour \(R=461.6\,\text{J}\,\text{kg}^{1}\text{K}^{1}\), the value is calculated by \(R_g/M_w\) with \(R_g= 8.3144621\,\text{J}\,\text{mol}^{1}\text{K}^{1}\), the ideal gas constant, and \(M_w=0.018016\,\text{kg}\,\text{mol}^{1}\), the molar mass of water.
The formula of this density model is presented on page 20 of [21].
In the application, the vapour density related terms in the mass balance equation are multiplied with \(1S\) with \( S \), the water saturation. Therefore the application of the water vapour density model is naturally restricted in the unsaturated zones.
It belongs to vapour_density. That means the name of this property is vapour_density. Besides, it has no parameter to be input.
No additional info.
Used in no endtoend test cases.