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Simulating particle dynamics with the Discrete Element Method (DEM)
Due to the discontinuous nature of granular materials, particle dynamics simulation requires a different solver approach compared to the classical Computational Fluid Dynamics (CFD). Particle simulation software Omnis™/Mpacts, helps designers of industrial processes understand, analyze, and solve the complex system properties of particle interactions without the need for experimental prototypes. Thanks to the Discrete Element Method the results are highly reliable while engineering time remains minimum.
Particle interaction in industrial processes
Around 80% of all industrial processes are estimated to deal with particulate materials and particle interactions.
Examples can be found in:
- Food processing: fruit bruise analysis, mixing and blending…
- Heavy equipment: conveyor belts, hoppers, dump truck…
- Agriculture equipment: combine harvesters, tractors, tillage…
- Pharmaceutical and biotech: tablet coating, powder spreading, fluidized bed…
- and many more sectors
Fruit bruise reduction
Separation grain kernels and crop
Dedicated features and post-processing in Omnis™
Omnis/Mpacts combines the power of the advanced DEM solver Mpacts with the user-friendly Omnis interface and all its capabilities from the pre-processing to co/post-processing in one workflow.
Offering all the benefits of the Omnis platform:
- Straightforward setup of the mechanical motion
- Surface materials definition
- Particle classes definition in the tree interaction
- Interactive control volume definition
- Automatic generation of the particle contact laws
- Particle post-processing
- and much more
For a demo and more detailed information VIEW WEBINAR
Discrete Element Method simulation (DEM)
The discrete element method works by explicitly computing all forces acting on individual particles that are described in a domain (there is no mesh). These forces are computed starting from geometrical information such as overlap and contact areas. Using a model, such as the Hertz model, contact forces are obtained. These forces are then integrated into new velocities and positions (see video to the left).
Compared to the Finite Element Method, the fundamental difference and advantage is that DEM does not need a subdivision of space. Particles are explicitly represented by their position, shape, and orientation.
This offers a huge flexibility in representing the shapes and interaction mechanics of the particles, leading to highly accurate and reliable simulations.
Not only spheres: multi-shaped particles
Primary DEM formulations assume particle shapes to be perfect spheres, as this method requires minimal computational effort. However, the ability to simulate multiple-shaped particles is essential to meeting industry requirements.
This is where Omnis/Mpacts offers another unique and significant advantage: it can represent all possible particle shapes, preserving their physical properties entirely. Spheres, cylinders, polyhedra, capsules, fibers, sheets, and vesicles; they are all available in both rigid and deformable forms.
The Mpacts solver is integrated into Omnis version 5.1. This version is focused on mechanical agitation applications such as mixers, conveyor belts, dump trucks, screw conveyors, etc. Its integration is continuous and some of the expert features described below will be released in future versions.
How a product gets damaged or why it breaks apart is often important to know for robust and high-quality production. Omnis/Mpacts therefore includes damage/breakage models that compute the onset and extent of damages. Custom damage/break models are also available for dedicated mechanisms.
The study of fluid flows is essential for many industrial processes. A typical example is the simulation of the flow in an artery bifurcation for the biomedical industry. In this simulation, particle movement and collisions are performed using the DEM, while the fluid is simulated using CFD. Two-way coupling is performed. The particles influence the flow pattern: the flow will look for the 'easiest' path through the particle stacking, and through drag forces, the flow will also drive the motion of the particles.
Several parts of a machine are often mechanically linked with coupled motions. The coupling is usually done through rotational or translational constraints or a combination of both. The rigid-body functionality of Mpacts ensures a straightforward and smart definition of a coupled-motion machine, while maintaining high-speed simulations.
- Arbitrary particle shapes
- Various material definition
- Numerous definition of solid mechanical motion
- Diverse particle contact interaction
- Dedicated particle post-processing
- Packing/stacking simulation
- Mixing model
- Impact prediction
- Powder mixers
- Crop flow in agricultural machines
- Soil tillage equipment
- Conveyor belts