Validation of OpenFOAM modeling of additive manufacturing melt pool dynamics against geometric and thermal experiments

Current research in additive manufacturing focuses on understanding the underlying physics of defect formation in parts. Multiphysics models are key to planning builds with minimal defects, but these models must be validated with experimental data to ensure meaningful predictions. We present experimental validation of a model for L-PBF melt pools using the OpenFOAM® open-source computational fluid dynamics (CFD) package that includes simulation of solid, liquid, and vapor phases. Solvers that simultaneously treat melt pool and vapor/gas flow physics are relatively new among existing L-PBF simulation tools. Solver parameters such as the Fresnel and mass accommodation coefficients are fit based on validation against ex-situ geometric data and in-situ thermal images. The results are compared to simulations using the semi-analytical Eagar-Tsai model, ANSYS Mechanical®, and FLOW-3D®. OpenFOAM simulations of 316L stainless steel melt pools show good agreement with both experimental results and similarly validated FLOW-3D simulations over a range of laser processing conditions. Vapor plume velocities are reported at over 250 m/s, and including a layer of pre-sintered powder shows increased melt pool variability and ejection of spatter particles. Results demonstrate the importance of validating models on multiple forms of experimental data and show the solver’s ability to simulate vapor and gas flow data. Future simulations of vapor and gas flow will lead to better understanding of L-PBF phenomena such as entrainment spatter, spatter trajectories within the gas flow, and vapor plume obstruction of the laser source. • OpenFOAM multiphysics CFD model fit to experimental geometry and temperature data. • Model can simulate spatter events, vapor plume, and gas flows above the powder bed. • Plume velocities found to be on the order of 100x greater than melt pool velocity. • Stronger flow in OpenFOAM melt pools affects temperatures in the melt pool width.