Discrete Element Method Particles
The Discrete Element Method (DEM) models the particle behavior within the simulation.
The particle equations of motion determine how the particles interact with each other and with solid boundaries. The image below shows the effect of particle-particle collisions and particle-wall collisions.
If a particle spans 3 or more mesh partitions (due to small cells and a high number of computational processes), the solution can miss particle-particle or particle-wall collisions, or record them late. To avoid this error, either use a coarser mesh, or increase the size of mesh partitions by reducing the number of processes.
As the DEM model simulates solid particles, the only available Lagrangian phase material models are solid, multi-component coal, multi-component solid, and liquid-solid-gas. Similarly, the only available Lagrangian phase equation of state models are constant density and polynomial density.
The DEM Particles model is represented in the Lagrangian phase by the DEM Particles node.
DEM Particle Types
DEM Lagrangian phases include phase models that allow you to select the type of the particles as:
- DEM Particles—The general particle model prerequisite to all the other DEM particle models.
- Spherical particles—Single spherical particles.
- Coarse Grain particles—Larger spherical parcels each representing multiple smaller particles. This model can reduce computational cost.
- Composite particles—Non-spherical particles composed of spheres joined by fixed bonds. See also Sphere-Filled Parts.
- Particle clumps—Non-spherical particles composed of spheres joined by breakable bonds to model fragmentation.
- Cylindrical particles—Exact cylinders that are computationally cheaper and can be more precise than approximations of composite spheres.
- Capsule particles—Round-capped cylinders, a widely used, computationally inexpensive shape.
- Polyhedral particles—Particles of any polyhedral shape.
- Flexible fibers—Fibers composed of bonded particles.
You can specify the structure of particle clumps or composite particles by either of two methods:
- Individually Composed particles—You specify the structure using the particle shapes editor.
- Sphere-Filled Parts—You specify the number of spherical particles to use and Simcenter STAR-CCM+ uses them to fill out a specified part.
While the Particle Clumps model defines clusters of particles that are injected with the inter-particle bonds already formed, the Parallel Bonds model forms bonded clusters from colliding particles after injection. For both these models, subsequent particle interaction and cluster breakup behaves in the same way.