No abstract

We present a Computational Fluid Dynamics (CFD) framework for the numerical simulation of the Laser Metal Deposition (LMD) process in 3D printing. Such a framework, comprehensive of both numerical formulations and solvers, aims at providing a sufficiently exhaustive scenario of the process, where the carrier gas, modeled as an Eulerian incompressible fluid, transports metal powders, tracked as Lagrangian discrete particles, within the 3D printing chamber. On the basis of heat sources coming from the laser beam and the heated substrate, the particle model is developed to interact with the carrier gas also by heat transfer and to evolve in a melted phase according to a growth law of the particle liquid mass fraction. Enhanced numerical solvers, characterized by a modified Newton-Raphson scheme and a parallel algorithm for tracking particles, are employed to obtain both efficiency and accuracy of the numerical strategy. In the perspective of investigating optimal design of the whole LMD process, we propose a sensitivity analysis specifically addressed to assess the influence of inflow rates, laser beams intensity, and nozzle channel geometry. Such a numerical campaign is performed with an in-house code developed with the open source Finite Element library, and publicly available online.

We present a Computational Fluid Dynamics (CFD) framework for the numerical simulation of the Laser Metal Deposition (LMD) process in 3D printing. Such a framework, comprehensive of both numerical formulations and solvers, aims at providing an exhaustive scenario of the process, where the carrier gas, modeled as an Eulerian incompressible fluid, transports metal powders, tracked as Langrangian discrete particles, within the 3D printing chamber. On the basis of heat sources coming from the laser beam and the heated substrate, the particle model is developed to interact with the carrier gas also by heat transfer and to evolve in a melted phase according to a growth law of the particle liquid mass fraction. Enhanced numerical solvers, characterized by a modified Netwon-Raphson scheme and a parallel algorithm for tracking particles, are employed to obtain both e ffi ciency and accuracy of the numerical strategy. In the perspective of investigating optimal design of the whole LMD process, we propose a sensitivity analysis specifically addressed to assess the influence of inflow rates, laser beams intensity, and nozzle channel geometry. Such a numerical campaign is performed with an in-house C++ code developed with the deal.II open source Finite Element library.

The present work deals with the nonlinear multiphysics advection-diffusion problem where non-stationary Navier-Stokes equations for incompressible flows are coupled with heat transfer equations.Although a large variety of numerical methods is widespread in literature, a sufficiently comprehensive investigation, to the best of authors' knowledge, has not been provided yet when aiming for high performances on both accuracy and efficiency, either by solving these problems jointly or separately. To this end, we propose a modified Newton-Raphson (mNR) scheme, based on a fully nonlinear formulation and employing standard Lagrange Finite Elements, implemented in an in-house C++ code using the open-source deal.II library. The proposed method is first validated against consolidated results available in the literature, testing fluid motion equations first alone, and then coupled with thermal convections. Then, its performance is highlighted by comparison with enhanced schemes, ad-hoc implemented, approaching the coupled problems through projection methods. Through a wide numerical campaign, we finally prove that the mNR scheme is able to achieve higher level of accuracy and efficiency with respect to the other considered methods. The C++ code implementing the proposed mNR scheme together with those employed for comparisons is freely available at https://doi.org/10.5281/zenodo.8192391.