Numerical simulation of particles flow in Laser Metal Deposition technology comparing Eulerian-Eulerian and Lagrangian-Eulerian approaches

The present work deals with the numerical prediction of the particle flow within a three-way nozzle in Laser Metal Deposition (LMD) technology adopted during additive manufacturing processes. In particular, the paper focuses on CFD (Computational Fluid Dynamics) simulations of the particle flow problem, regarding the coupling between a fluid phase, i.e., the carrier gas, and a solid phase, i.e., a metallic material powder that is delivered through the nozzle of the LMD machine. Two different numerical approaches are investigated, both implemented in a in-house code using OpenFOAM open source C++ toolbox. The former is based on a mixed formulation, combining an Eulerian description of the carrier gas flow with a Lagrangian description of the particle flow. The latter on a pure Eulerian formulation of both carrier gas and particles. In agreement with the experimental evidences, the present work compares the two approaches in terms of capability of simulating some key physical features of the LMD process, i.e., the geometrical properties of the powder cone formed out from the nozzle.