EDEM Simulation Sequence

Depending on where the UDL lies in the chain, each stage connects to the relevant UDL (if applicable) before performing its main function (such as calculating contacts).

The following diagram represents UDL libraries when they are called during EDEM’s simulation sequence.

1. Move geometries.
2. Generate new particles by calling each registered particle factory in turn (some of which may be UDLs).
   A Custom Factory typically uses the Material and Particle Prototype defined in the EDEM Creator and can determine the position, scale and properties (such as velocity and orientation) of the material in the EDEM simulation.
3. Detect contacts.
   Contacts are Particle-Particle or Particle-Geometry. A single particle can have multiple contacts at any Time Step.
4. Invoke the Contact Model chain for each contact.
   Each Contact Model in the chain is executed in order from top to bottom, irrespective of whether it is a UDL or built-in model.
   There are two different contact model chains: one for particle-to-particle contacts and one for particle-to-geometry contacts. Your UDL can be loaded into one or both of these as required.
5. For any given model EDEM particle, material and geometry data is passed to the Contact Model API, this includes information such as the particle positions and velocities.
   Depending on the API version used calculated forces from other API or in-built models may be also provided to the custom model. 
   In EDEM 2018.2 Contact Model API version 2.6.0 additional Contact Model chaining was implemented. The in-built Contact Models will receive the calculated force from the model above and provide this to the contact model in the following chain.
6. API models created with Contact Model API version 2.5.0 or earlier will not receive forces from models in the chain above however they will provide forces for any Contact Models in the following chain.
7. API models created with Contact Model API version 2.6.0 or later will receive forces from models in the chain above and provide forces for any models in the following chain. 
8. Apply the Particle Body Force chain to each particle in the system.
   Particle Body Force models in the chain are executed in order, irrespective of whether it is a UDL or built-in model.
9. Update particles based on the forces applied to them in this Time Step.
10. If there are more time steps, repeat from step 1 or click Finish.

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