The MPM is an add-on module based on a suite of UDF functions that models transport of large particles in a fluid flow, particle-particle and particle-wall interactions, as well as particle tracking. The MPM is designed for macroscopic particles that are well-resolved across a particle diameter by at least 20-30 fluid cells.
The MPM is not a general purpose model. The model has been shown to give good results for
applications in which macroscopic particles with Reynolds number 
<< 1 move in a flow having a fluid-to-particle density ratio,
, in the order of 1. For other values of 
and 
, the drag prediction may not be accurate; in such cases the MPM may be used
when drag is not important.
Note the following limitations when using the MPM:
Mass transfer and radiation cannot be modeled.
The MPM is not compatible with moving/deforming meshes.
Simulations of densely-packed particles are not supported because only one collision event is handled for each particle time step.
There is no direct interaction with DPM particles (collision).
Coupling with Multiphase models is possible, but manual settings are required for source terms (mass, momentum, and heat).
Sub-iterations of MPM particle tracks within one time step are not supported.
The MPM is not compatible with mesh interfaces.