This feature is available when the Volatilization in partially saturated porous media check box is selected on the Settings window for the physics interface.

Use this feature to model mass transfer at the boundary due to volatilization. The feature can be added on boundaries of a Partially Saturated Porous Media domain. In this case the porous media contains a liquid phase and a gas phase. The species dissolved in the liquid are assumed to be vaporized at the boundary, and transported into the surrounding bulk region due to convection and diffusion. The mass transfer at the boundary is defined as

where hc is the mass transfer coefficient, kG,c the volatilization coefficient, and cGatm,c the concentration in the surrounding atmosphere.

Enter a Mass transfer coefficient hc defining the transfer into the surrounding media. This can be given by boundary layer theory. When assuming that no convective flow is present in the surrounding, the mass transfer coefficient can be defined from the gas diffusion coefficient DGc and the thickness of the diffusion layer ds in the manner of

Also give the atmospheric concentration for each species, cGatm,c. The Volatilization coefficient kG,c for each species are taken from the adjacent Partially Saturated Porous Media domain.