Dual-Grid Multiscale approach for CFD-DEM Couplings
Crater formation due to particle impact (G. Pozzetti and B. Peters IJMF 2017)
In a CFD-DEM coupling, when the underlying flow gets complicated, like in presence of multiple fluid phases or complex turbulent structures, a wide range of physical scales are normally influencing the flow behaviour. It often happens that not all of the fluid scales, that must be solved in order to obtain an unique solution for the flow, are significantly affecting the discrete phase. This can for instance happen with inertial particles traveling close to boundary layers of a turbulent flow, or in presence of complex interface dynamics. This translates, within grid based approaches, in the requirement of local or global refinements of the computational grid. The latter may need to be locally smaller or larger than the particle diameter in order capture the correct characteristic wavelength, and produce grid convergent results. This is in contrast with the requirement of the standard volume averaging techniques that is performing better when dealing with uniform domain discretizations. The XDEM platform allows to overcome this problem by using a Dual Grid Multiscale Approach (DGMA) based on the definition of two different meshes. One mesh will be used to compute the solution of the fluid, it will be defined according to the fluid specific requirements s to produce grid convergent results. The other mesh is used to project Particle related fields into Eulerian ones and to solve the fluid-particle coupling problem recovering only the necessary information for the fine fluid solution.
The research is funded through resources of the University of Luxembourg.