(382b) A Fully Coupled CFD-DEM Algorithm for S-L Mixing in Stirred Vessels

Solid â?? Liquid mixing in high viscosity liquid and/or high solids concentration is a challenging problem due to the solid-solid and solid-liquid phase interactions. Just suspended speed (N_js), suspension height (H_s) and the power consumption can vary not only with the material properties but also with the design of tank and impellers.

In the past, there was been work presented using multiphase CFD methods, specifically the Eulerian approach. Such approach has shown promising results for turbulent conditions [1]. Further work has also been carried out where Discrete Element Modeling for particle flows was co-simulated with CFD simulations for fluid flow [2]. Often, this could mean creating and maintaining two different codes for the two portions of the flow.

In this work we would be presenting a method of performing such simulations in a coupled way using a single code STAR-CCM+ rather than in a co-simulation framework. For DEM phase â??pressure gradientâ? and â??drag forcesâ? are included in integrating equations of motions for each particle. The continuum field for fluid solution is obtained from solving Navier â??Stokes equation based on the local mean variables over computational cells. These local variables include the solid fraction for the sources of momentum due to particles. Comparisons with existing literature data will be presented which represents a lab operation of the stirred vessel. Future outlook on translating this for a more practical operation of the vessel will be outline.

References

1. Aglave, R., Feng, J., Eppinger, T, and Lo, S., Predicting power consumption at high solids concentration in mixing vessels
2. Bertrand, F., Blais, B., Lassaigne, M., Fradette, Goniva, C., A robust and efficient CFD-DEM method for investigation of viscous solid-liquid mixing.