Mixture Multiphase (MMP)

In the Mixture Multiphase (MMP) model, mass, momentum, and energy are treated as mixture quantities rather than phase quantities. Simcenter STAR-CCM+ solves transport equations for the mixture as a whole, and not for each phase separately. The model is computationally more efficient than models that simulate each phase separately.

The Multiphase Mixture (MMP) model is similar to the Volume of Fluid (VOF) multiphase model. This model can be used for an arbitrary combination of phases where the phase interactions can be of any kind. Indeed, VOF can be considered a special case of Multiphase Mixture, with a specialized convection scheme and no diffusion. The Multiphase Mixture model is intended for use as a replacement for the more computationally expensive Eulerian Multiphase (EMP) model. However, in some cases, large variations between phase quantities are not well-resolved.

The Multiphase Mixture (MMP) model is not suitable for use when the mixture properties are not good approximations of the properties of the phases. In this case, the EMP model is the better choice. The Multiphase Mixture (MMP) model is intended for use in cases where the grid is too coarse to resolve the interface between the phases. Consequently, this model cannot be expected to resolve a sharp interface, even on a fine grid. If you expect stratified free surface flow with a sharp interface between the phases to occur as part of your dispersed mixture multiphase simulation, you can use Adaptive Interface Sharpening (ADIS) together with Large-Scale Interface Detection to identify sharp interfaces and resolve them on the computational mesh. This capability allows you to model two flow regimes—dispersed and stratified—in the same simulation. As such, the Mixture Multiphase (MMP) model can be used as a computationally less expensive alternative to the VOF model for modeling such flow regimes.

You can apply the Multiphase Mixture (MMP) model to cases where you can use weighted physical properties to represent a mixture of phases. A single set of equations for momentum, mass and energy transport is solved for the mixture, together with transport equations for phase volume fractions. The slip velocity between phases can also be modeled.

Examples of industrial applications of the Multiphase Mixture (MMP) model include steam generators, engine cooling systems, and fuel cells.