Multiphase Transport

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The framework for multiphase transport in a porous zone (see Fig. 1) is already laid out through the single phase transport in porous media. When the porous medium is saturated with both liquid and vapor, the governing equations for liquid and vapor as well as solid matrix must be specified. In addition, the solid-liquid-vapor interactions play an important role in heat and mass transfer applications. The governing equation for the liquid and vapor phase must also consider possible phase change between liquid and vapor. Chapter 5 is entirely dedicated to problems of involving solid-liquid-vapor interfacial phenomena. Problems that directly solve the solid-liquid-vapor phenomena are typically applied to a single pore.

The premise for both the multifluid model (MFM) and the multiphase mixture model (MMM) for solving multiphase porous media are the volume-averaged Navier-Stokes equations. The major assumption for these models used in a porous medium is that the flow is considered noninertial. One of the benefits of a noninertial flow is that it behaves very well and is in the laminar flow regime. Therefore, the deviatoric values from the volume-averaged equation are neglected without compromising the accuracy of the solution. This approximation is reasonable as the pore size is very small, which makes viscous affects dominate. The MFM solves both phases separately, along with the details of each phase, such as temperature, and species mass fraction. The MMM adds the governing equations for each phase, and converts the flow variables into their mass-averaged values counterparts.

 Typical elemental volume with periodic dispersion of phases.
Figure 1: Typical elemental volume with periodic dispersion of phases.

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