Mill with liquid-gas surface

Warning

This tutorial is included in and relies on functionality that is available in the CFDEMcoupling-Multiphase package.

The miniBallMill showcases a small rotating drum which is half filled with water. The particles are moved up by the baffles at the drum wall which also moves the water and creates waves on the liquid-gas interface.

Note

This case is located in CFDEMcoupling/useCases/miniBallMill.

Models used

• Particle forces:

  • The drag force is computed by the KochHill drag model.

  • Alteration of effective gravity forces due the difference of fluid and particle densities is modelled by the Archimedes force model.

• Particles are mapped to CFD cells by the turboEngine locateModel. This locateModel is specifically enhanced for moving geometries. In the present case it must be used to correctly locate the particles in the moving mesh region which requires the locateModel to track mesh updates. This tracking must be activated by the user by setting allowParticlesInMovingRegion true.

• The voidfraction is computed by the divided voidfraction model.

• Momentum exchange between particles and fluid is computed in an implicit manner, see Zhou et al. (2010), JFM.

• The size of the CFD cells is restricted by the resolution requirements of the Volume-of-Fluid method employed. Consequently, the particles are rather large with respect to the size of the CFD cells. To relax the constraints on the ratio of particle to cell size in unresolved CFD-DEM (see Introduction into CFD-DEM), the voidfraction and momentum exchange fields are smoothed by an additional smoothing model: constDiffSmoothing.

Results

Figure 1: Particles colored by their radius and liquid-gas interface, also available as full video.

Figure 2: Particles colored by their vertical velocity component and liquid-gas interface.