When particles coexist with a fluid, such as in gas-solid and liquid-solid fluidised beds, the hydrodynamic interactions can be very complex and require sophisticated numerical models for accurate simulations. We have proposed an optimal permeability model to effectively eliminate the errors in the Volume Penalisation (VP) method. The simulation above shows density segregation in a liquid-solid fluidised bed where the heavier (purple) particles spontaneously concentrate at the bottom due to the imbalance between the gravity and hydrodynamic forces.

Gas-liquid-solid three-phase flows can be encountered in many industrial processes including chemical reactors, slurry mixing and battery manufacturing. However, current understanding of three-phase flows is very limited due to extremely complex gas-liquid, fluid-solid and three-phase interactions. We have developed a novel three-phase simulation model based on the interface capturing method, which can accurately account for the interactions between the phases. The example simulation above demonstrates a bubbly flow with neutrally-buoyant and differently-shaped particles where the particles take preferential orientations depending on the shape.

Solid surface wettability plays an important role in many three-phase flows such as wet granulation, particle coating and 3D printing. Accurately resolving the movement of three-phase interfaces on particle surfaces is crutial to account for the interaction forces, i.e., capillary forces. This example simulation demonstrates the dynamic liquid bridge bonding two non-spherical particles using the Immersed Free Surface (IFS) and Continuous Capillary Force (CCF) models both developed by our research group.