(35d) Development and Application of Coupled CFD-DEM Models  for Complex FLUID Particle Systems (FIBROUS MATERIAL, SLURRIES ETC…) in Industrial Scale Processes

Bharadwaj, R., ESSS North America
Many processes in the chemical industry involve the both fluids and particle flow.. Slurry mills, cyclones, desanders, pneumatic conveyors, grains drying and sorting, fluidized beds and catalytic reactors are just a few examples of granular-fluid systems. In order to predict the behavior of such systems accurately using a first principle modeling tool, it is important to model the effect of fluid flow on the particles. Design and scale-up, as well as optimization of such processes, require a deep understanding of the thermo-hydrodynamics, which is determined by the particle-level interactions between the fluids, particles, and boundaries.
The complexity of the fluid-solid flow present in these systems makes modeling them a challenging task. The primary source of difficulty is the wide range of length scales existing in these system, as the largest structures are a few meters whereas the momentum, heat and mass transfers occur at the micrometer scale of the interactions between particles and fluid and particles. Although, there are some inherent challenges in developing CFD-DEM models, such as large computational run times, the advent of fast GPU hardware and advanced algorithms are mitigating these limitations.

In this work, details of the DEM-CFD integration between two commercial softwares, Rocky® (DEM) and ANSYS Fluent® (CFD) will be addressed. In particular, the coupling formulation for non-spherical particles shapes and a wide variety of application that includes flexible fibrous material, slurry flows etc… will be evaluated. In addition, a few application examples, including both one-way and two-way coupling cases will also be presented. These models capture the discrete nature of the particle phase while maintaining the computational tractability. This is accomplished by not solving the detailed fluid field at the particle level, which enlarges the range of equipment and processes that can be studied with numerical simulations.