Coupled simulations with particles

Coupled Particle and Finite Element Simulations

In many applications mesh-free particle simulations offer distinct advantages compared to grid-based finite element or finite volume methods. Mesh-free methods are both, an alternative and a complement. For example:  the simulative investigation of granular materials, their transport in fluids or their interaction with structures or components.

From the user perspective the combination of mesh-free particles with grid-based codes, to make the respective strengths of both methods for an application usable, is our main focus. We provide our developments forth this link.

The class of particle codes here are on the one hand the DEM codes (DEM = 3D Discrete Element Method) and on the other hand, the SPH codes (SPH = 3D smoothed-particle hydrodynamics).

The coupling of DEM with structural mechanics (Finite Elements) is particularly attractive for modeling the contact of granular matter with flexible bodies. The coupling will take place at the surface of a body which is in contact with the granular material. The nodal-points of the coupled surface are known to both the DEM and the FEA program. In the simplest case, both programs use the same integration time step.

The DEM program sends the forces of the repulsion contact, cohesion and friction as nodal forces to the FEA program, which then calculates the displacements and velocities at nodal points and returns the values to the DEM program. The displacements affect the shape of the elastic structure in the contact with granular matter, which in turn causes changes in the nodal forces.

The coupling between SPH codes and structural mechanics corresponds to a classical fluid-structure interaction (FSI), but the mesh- free SPH code is not subject to the limitations of the mesh-based flow-codes.

Services

Fraunhofer SCAI already provides the link to reputable commercial structure simulation codes like DS / Simulia (formerly Abaqus), Ansys, MD.Nastran, MSC / Marc., as well as to open source codes like CalculiX or Elmer. Any SPH or DEM code can already work with any of these structural codes in a co-simulation. A (volume-) coupling with CFD codes to model highly concentrated suspensions using DEM, for example, sedimentation, are currently under development.

On the SHP and DEM side this co-simulation, the code SimPARTIX® (www.simpartix.de) of Fraunhofer IWM is currently used at SCAI.

For users interested in a co-simulation with industrial relevant particle codes like Itasca PFC3D, EDEM, Rocky-Dem, Newton, etc., we offer assistance in binding and integrating those codes into the existing software platform. This applies equally to any applied SPH- or DEM- in-house code.

Fraunhofer SCAI has an excellent computing infrastructure with a fast HPC compute clusters to perform the computationally intensive particle-simulations quickly. For already reliable calibrated particle models, we also offer the particle simulation as a service.

 

Solution

The following coupling algorithms are available:

  • Event based
  • Synchronous time increment
  • Asynchronous time increment

Structure-structure interaction

 

Reversible elastic structures

 

Elastic-plastic structures

 

Interaction between tire, ground and soil

Fluid-structure interaction

 

SPH

 

Fluid-structure interaction with leaks

 

Fluid-structure interaction with large deformations and changes in volume