The gravity and Buoyancy forces are automatically accounted for in the Ansys Fluent MPM model.

Other particle-particle field forces, such as electrostatic, magnetic or cohesive forces, are implemented in the MPM using a potential force model in which inter-particle field forces acting on the particle are defined as:

(13–9)

The model constants , , , and can be indirectly related to the tensile strength or cohesive forces in solids.

In a similar manner, particle-wall field forces are defined as:

(13–10)

The signs of the constants and determine whether the particle-particle and particle-wall field forces are attraction or repulsion forces.