Coarse Grain Models Reference

In these models, each simulated particle is a parcel that represents multiple smaller identical particles. Both models calculate fluid-particle interactions on a single representative particle and apply the results to all of the smaller particles in the parcel. For particle-particle interactions:

• The Coarse Grain Particle model calculates the contact forces on a single representative particle pair, one from each interacting parcel, then uses these forces in a number of contact events equal to the number of particles in the parcel with the most particles.
• The Parcel Contact Coarse Grain model treats each parcel as a single large particle and calculates the contact between them. This method uses a larger time-step and so gives a higher computational speed at the cost of a small loss of fidelity in describing the details of individual contacts.

If you select the Linear Cohesion model with either of these models, the models also calculate cohesion forces between particles in the parcel and between particles and the wall. For more informtation, see the Linear Cohesion Model Reference.

The number of individual particles per coarse-grained particle depends on injector conditions and values, set by Flow Rate Specification, Particle Size Specification, and Mass Flow Rate. The number does not have to be an integer.

The Parcel Coarse Grain Particle model is best used for fluidized bed applications, where accuracy of particle-fluid interactions is more important than accuracy of particle-particle interactions.

Do not use the Coarse Grain Particle models when the mesh size is smaller than the size of the coarse-grained particle.