16.7.2 Unidirectional Constant Rate Mass Transfer

The unidirectional mass transfer model defines a positive mass flow rate per unit volume from phase $p$ to phase $q$:

where

and $\dot{r}$ is a constant rate of particle shrinking or swelling, such as the rate of burning of a liquid droplet. This is not available for the VOF model.

If phase $p$ is a mixture material and a mass transfer mechanism is defined for species $i$ of phase $p$, then

where $y_{\rm p, i}$ is the mass fraction of species $i$ in phase $p$.