What You Can Simulate with CFDEM®coupling

CFDEM®coupling is the CFD-DEM extension for Aspherix®: it couples the Aspherix® DEM solver with a CFD solver, so particles and fluid exchange momentum, heat and mass in both directions. It comes in three packages: Premium is the base package for coupled particle-fluid simulations, and two optional top-ups extend it, Multiphase for gas-liquid-solid flows and Chemical for compressible, reacting flows.

A quick overview of what CFDEM®coupling adds to Aspherix®. The label on each card shows which package you need:

Watch CFDEM®coupling in action. These CFD-DEM simulations show particles and fluid working together in real engineering problems:

In a fluidized bed, a pneumatic conveyor or a filter, what happens to the particles depends on the fluid around them, and the fluid in turn is displaced and slowed down by the particles. CFDEM®coupling resolves this two-way exchange: every particle feels drag, pressure and buoyancy from the flow, and the CFD solver sees the particles as void fraction and momentum sources.

Drag laws cover all flow regimes, from dilute transport to dense packed beds, and work with every Aspherix® particle shape. Lift, virtual mass, turbulent dispersion, suspension viscosity, electrostatic and Lorentz forces complete the picture, and heat and species are exchanged between particles and fluid in the same simulation.

Most CFD-DEM simulations treat particles as smaller than the CFD cells. When particles are large compared to the mesh, such as pellets in a packed bed, lumps in a furnace or a single object in a flow, the flow around each particle has to be resolved. CFDEM®coupling does this with the Immersed Boundary Method (IBM).

Hybrid coupling decides per particle whether it is resolved or unresolved, and adaptive mesh refinement puts fine cells only where they are needed. The same method moves meshed geometries such as stirrers, baffles or lances through the flow.

Aspherix® and the CFD solver run side by side, each with its own MPI parallelization and domain decomposition. This keeps both efficient when the particles fill only part of the fluid domain, as in furnaces, shafts and fluidized beds. The workflow is the same on a workstation and on an HPC cluster.

Coarse graining represents groups of particles as larger parcels, and the scaling is applied to drag and to heat and mass exchange as well as to the contacts. Dynamic coarse graining adds detail only where it matters. On GPU, coupled CFD-DEM runs in beta via SPUMA on Linux, with both Aspherix® and the CFD solver on the GPU.

Default settings for robust or precise runs, smoothing of coupling fields and stability checks make coupled cases easier to set up and keep them stable.

Coupled simulations produce two kinds of data: particle data from the DEM and fields from the CFD. CFDEM®coupling brings them together, maps particle quantities onto the CFD mesh and averages fields in time, so you get numbers such as slip velocity, local particle concentration or total momentum exchange.

Results are written for ParaView, including particles with temperature and pathlines, and utilities decompose, reconstruct and export CFD-DEM cases. Wrapper scripts run and clean up a coupled case with a single command.

In kilns, gasifiers, reduction reactors and dryers, the gas reacts with the particles, heats them, dries them or burns them. The Chemical package adds a compressible, reacting CFD-DEM solver for these gas-solid systems.

Reactions take place in the gas and between gas and particles, and the reaction rates account for the local void fraction. Particles change their mass as they react. Sprays wet the particles and form films on them, and radiation transports heat at high temperatures. Particle temperature statistics and additional output formats come with the package.

Need more details? Download the Spec Sheets for the different CFDEM®coupling packages here: