Meshfree DEM Workflow

Set up a meshfree DEM simulation as you would other DEM simulations. Meshfree DEM simulations have no volume mesh of interiors. In other regards, this workflow has many of the same steps as the mesh-based workflow, although the mesh-based workflow also includes steps related to continuous-phase physics.

To model meshfree DEM:
  1. Ensure that your simulation has an overall bounding domain in which all particles and other solid parts are contained. If your solid geometry does not already have an outer domain then you can create one using a simple shape geometry part. This part must be a closed, watertight volume. Assign this part to a particle region. Do not use the new particle region as the input to any volume mesh operation.
    NoteMultiple particle regions connected with imprinted internal interfaces are also allowed for setting meshfree DEM model.
  2. Assign all remaining geometry parts to solid regions. Do not use the solid regions as input to any volume mesh operation.
    NoteYou are not required to modify the initial surface mesh in solid regions or particle regions, but it is allowed and can be useful for more accurate analysis of forces on boundaries.
  3. Within the physics continuum, and with Auto-select recommended models active, select the Meshfree DEM model from the Optional Models group. The following models are selected automatically:
    Group Box Model
    Optional Models Lagrangian Multiphase

    Multiphase Interaction

    Solution Interpolation
    Multiphase Dem Discrete Element Model (DEM)
    Time Implicit Unsteady
  4. Create as many Lagrangian phases as you require for the DEM simulation:
    1. Open the Lagrangian Multiphase node to expose the Lagrangian Phases node.
    2. Right-click the Lagrangian Phases manager node and select New > Free-stream Phase.
      A new Lagrangian phase node appears with the default name Phase 1.
    3. Rename the node if desired.
  5. For each Lagrangian phase, define the particle physics and material as follows:
    1. Right-click the [phase] > Models node and click Select Models...
    2. In the phase model selection dialog, within Particle Type, select DEM Particles.
    3. Continue by selecting a DEM Particle type. See DEM Particle Types for a list of choices.
    4. Choose further phase models as necessary to simulate the physics present in the scenario you are modeling. Include an appropriate material model.
    5. When done with selecting models, close the dialog, and review the phase model nodes in the tree. Some models require further selections in their properties.
    6. Set the phase material properties.
  6. Create phase interaction nodes for interactions between all particle phases including each phase with itself and each phase with each kind of boundary. For example, for particle phases A and B confined by a wall, create interactions for A-B, A-A, B-B, A-wall, and B-wall.
    1. Open the Multiphase Interaction node to expose the Phase Interactions manager node.
    2. Right-click the Phase Interactions manager node and select New > [first phase] > [second phase]. Boundaries can be used as second phases. See DEM Phase Interaction Model Reference.
      A new interaction node appears with the default name Phase Interaction 1.
    3. Rename the node.
    4. Repeat steps b and c for each additional phase interaction.
  7. For each phase interaction, define the contact model:
    1. Right-click the [phase interaction] > Models node and click Select Models...
    2. In the phase model selection dialog, within Phase Interaction Topology, select DEM Phase Interaction if it has not been automatically selected.
    3. Select a model within DEM Contact Model.
    4. Choose further interaction models as necessary to simulate the physics present in the scenario you are modeling.
      Models for drag, lift, or other effects of fluid flow are not available with Meshfree DEM.
  8. Define the source of DEM phases within the simulation: create injectors and set their properties. See Working with Injectors. In most cases, the Random Injector is the best choice.
    The following injector conditions are specific to DEM:
  9. Adjust solver parameters to improve performance and scalability. See the Discrete Element Method Solver with particular attention to the Reordering Frequency and Skin properties.
  10. Prepare for post-processing. DEM post-processing includes all features of Lagrangian post-processing, but also allows reporting on features of individual particles, such as contact between particles, particle shape, and rotation. See Simulation History Phase Data and Discrete Element Method Field Function Reference. To track forces applied to boundaries by DEM particles, activate the DEM Boundary Forces model in the physics continuum. See DEM Boundary Forces Model reference.
  11. Run the simulation.
  12. Review the results. These can include instantaneous data, particle track data, and boundary sampling, as with Lagrangian post-processing, but can also include data on particle contacts, angular momentum and kinetic energy, collision history, and changes in particle shape.