1. ExaDEM Software
1.1. Overview of ExaDEM
ExaDEM is a software solution in the field of computational simulations. It’s a Discrete Element Method (DEM) code developed within the exaNBody framework. This framework provides the basis for DEM functionalities and performance optimizations. A notable aspect of ExaDEM is its hybrid parallelization approach, which combines the use of MPI (Message Passing Interface) and threads (OpenMP). This combination aims to enhance computation times for simulations, making them more efficient and manageable.
Additionally, ExaDEM offers compatibility with MPI``+``GPUs, using the CUDA programming model (Onika layer). This feature provides the option to leverage GPU processing power for potential performance gains in simulations. Written in C++17, ExaDEM is built on a contemporary codebase. It aims to provide researchers and engineers with a tool for addressing DEM simulations.
1.2. ExaDEM Capabilities
The following table provides a glossary of features supported by ExaDEM, categorized by their computational platform (CPU or GPU) and particle type (Sphere or Polyhedron). Please note that this information is indicative and may be subject to change based on updates or modifications to the ExaDEM framework.
Features |
Sphere(CPU) |
Sphere(GPU) |
Polyhedron(CPU) |
Polyhedron(GPU) |
|---|---|---|---|---|
Field Set Plugin |
✔ |
✔ |
✔ |
✔ |
I/O Files |
✔ |
✘ |
✔ |
✘ |
Paraview Files |
✔ |
✘ |
✔ |
✘ |
Particle Migration (MPI) |
✔ |
✘ |
✔ |
✘ |
Load Balancing (RCB) |
✔ |
✘ |
✔ |
✘ |
Numerical Scheme Plugin |
✔ |
✔ |
✔ |
✔ |
Regions |
✔ |
✔ |
✔ |
✔ |
Particles Generator |
✔ |
✘ |
✔ |
✘ |
Contact Law |
✔ |
✔ |
✔ |
✔ |
Gravity Force |
✔ |
✔ |
✔ |
✔ |
Quadratic Drag Force |
✔ |
✔ |
✔ |
✔ |
Driver Cylinder |
✔ |
✔ |
✔ |
✔ |
Driver Wall/Surface |
✔ |
✔ |
✔ |
✔ |
Driver type Ball/Sphere |
✔ |
✔ |
✔ |
✔ |
Driver type STL Mesh |
✔ |
✔ |
✔ |
✔ |
Contact Network File |
✔ |
✘ |
✔ |
✘ |
Note
With version 1.0.1, exaDEM can now run GPU calculations with polyhedra. Nevertheless, optimizations are required to achieve good performance. These are currently being implemented.
1.3. Default Execution Graph With ExaDEM
ExaDEM is based on the operator execution system implemented by the ExaNBody framework. In particular, this allows us to define a set of default operators for ExaDEM to run a DEM simulation following a default Verlet Vitesse integration scheme. ExaDEM offers two variants, depending on whether you want to simulate spherical particles only or spheropolyhedron particles. To choose between these two variants, you’ll need to include either config_spheres.msp or config_polyhedra.msp at the beginning of your input file. If neither is defined, the simulation will not work. Including these files allows you to override certain operators left at nop (for no operation). The graph below shows the sequence of exaDEM’s main operators.
Note
Violet: These operators are only called with the polyhedra variant.
Blue: Numerical time scheme operators.