Averaged Fluid-Particle Flows

Key features in the fully-coupled unresolved CFD-DEM model, suitable for simulating and analysing larger scale multiphase processes

Three-phase flows

Three-phase modelling

  • Two-phase immiscible, incompressible fluid fully coupled with particles

  • Controllable fluid-fluid interface capturing with combined interface compression and diffuse interface techniques

[Video] Three-phase (gas-liquid-particles) fluidised bed

Complex moving geometry

Complex geometry modelled as additional solid phase

  • VP (Volume Penalisation) method with optimal permeability to model fluid-solid phase interaction

  • IFS (Immersed Free Surface) method to handle fluid-fluid interface inside the solid phase region

  • Synchronization with LIGGGHTS's mesh motion for moving wall/geometry

  • RANS turbulence model compatible with the VP method for turbulent flows

[Video] Gas-liquid-particles stir tank with complex geometry phase (rotating impeller)

Particle wetting

Particle behaviour at liquid surface

  • Surface tension and Laplace pressure at the fluid-fluid interface in particle bed

  • Particle wettability (fluid phicility/phobicity)

[Video] Hydrophilic vs hydrophobic particles on water (left: contact angle 30°, right: contact angle 150°)

System simplification, computational time reduction

Scaled-up particle model for two and three-phase flows

  • Particle size scaled-up to reduce number of particles for faster computation

  • All inter-particle and particle-fluid forces scaled accordingly to maintain system dynamics

[Video] Two-phase flow (gas-particles fluidised bed) with scaled-up particle model (left: original particles, right: scaled-up particles)

[Video] Three-phase flow (particle assembly falling into water) with scaled-up particle model (left: original particles, right: scaled-up particles)

Others

Smooth volume averaging

  • DBCG (Diffusion based coarse graining) method for smooth averaging of particle quantities across CFD cells and stable computation



Particle solid fraction in fluidised bed: conventional PCM (Particle Centroid Method) vs DBCG averaging