440a Eulerian Cfd Model for Cohesive Frictional Flow

Peter Spicka, Fluent Inc., 10 Cavendish Court, Lebanon, NH 03766

Granular flow in the frictional regime can be found in many industrial applications such as silos, dryers, hopper, pneumatic conveyors and particle coaters. Typical industrial systems involve large number of particles of different shapes and size distributions. In case of sufficiently small or moist particles, cohesion forces can significantly affect their flow characteristics. General belief is that these effects can be addressed only in the Lagrangian framework usually by DEM or MP-PIC techniques. Though very promising and accurate, these techniques require large computational resources and cannot handle systems containing more than several hundred thousand particles in reasonable time. On the other hand Eulerian models are almost independent on the number of particles and thus more suitable for large industrial systems. However, the implementation of frictional effect on the Eulerian framework is not yet fully understood and is based on semi empirical concepts of frictional pressure and viscosity. Last year we presented an Eulerian model capable of predicting solids pile up in an hourglass containing cohesionless dry sand. The model has been extended to include additional features such as solids compressibility, variable angle of internal and wall friction. Moreover, one of the first attempts to include cohesion effects in the Eulerian framework is proposed. All these effects were implemented as user defined functions in the commercial code Fluent 6.3. Model details, its demonstration and validation will be provided.