The coupled DEM-CFD approach is a promising alternative for modeling granular-fluid systems since it can capture the discrete nature of the particle phase while maintaining the computational tractability. This is accomplished by solving the fluid flow at the cell level instead of at the detailed particle level. Due to the reduced fluid calculations required, this technique enlarges the range of equipment and processes that can be studied with numerical simulations.
The coupling of DEM with a finite volume method for the solution of fluid phase in a computational cell level was first reported by [56] and [57], using the soft-sphere model and hard-sphere model for the interaction force between particles, respectively. Since then, numerous authors have published their work using the Euler-Lagrange type of model to study granular flow ([58],[59], [60], [61], [62], [63]), proving this approach as a very promising method.
In the DEM-CFD method, the fluid flow is obtained by the conventional continuum approach, providing information to calculate the fluid forces acting on individual particles while the motion of the particle is obtained by using a discrete particle method.
Some specific benefits to using the DEM-CFD coupled method vs. using CFD alone are listed below.
Unlike continuum methods, the motion of every particle is simulated, so particle-particle interactions are taken into account. Therefore there is no need to provide equations of state-motion of granular systems, which are quite difficult to derive.
By the same token, there is no limitation of low particle size concentration and particle size distribution is easily prescribed without increasing CFD solver computational cost.
It is possible to deal with non-spherical particles.
It is possible to model adhesive-cohesive materials by modeling the attractive force between a pair of particles and between particles and walls.
Additionally, particle-particle and particle-walls heat transfer as well as the convective heat transfer with the fluid can be included.