Comparative study of the main electromagnetic models applied to melt pool prediction with gas metal arc: Effect on flow, ripples from drop impact, and geometry

Abstract

The present work concerns the electromagnetic force models in computational fluid dynamics simulations of melt pools produced with electric arcs. These are commonly applied to gas metal arcs with metal transfer, in welding and additive manufacturing. Metal drop impact on the melt pool is thus included in this study. The electromagnetic force models applied in literature use either numerical solutions of Poisson equations or one of the two analytical models developed by Kou and Sun, or Tsao and Wu. These models rely on assumptions for which the effect on the melt pool predictions remains to be understood. The present work thoroughly investigates those assumptions and their effects. It has been supported by dedicated experimental tests that did provide estimates of unknown model parameters and validation data. The obtained results show that the assumptions that fundamentally distinguish these three models change the electromagnetic force, including the relation between its components. These changes, which can also be spatially non-uniform, are large. As a result, these models lead to significantly different recirculation flow pattern, thermal convection, melt pool morphology, bead dimensions, and free surface response to the metal transfer. We conclude by proposing conditions in which each of these models is suited or questionable.