The present work investigates thoroughly the approaches used to model the effect of pulsing the heat source in computational fluid dynamics simulations of melt pools produced with electric arcs. Pulsed arcs are commonly utilized in metal additive manufacturing, welding, and cladding, especially pulsed gas metal arcs to control the metal transfer. They are characterized by periodic changes over time that act on the melt pool through arc heat flux, arc pressure, and electromagnetic force. Different approaches are being used in the literature to close the modelling of these terms with respect to arc pulsation: time-averaged without calibration, with calibration of the electromagnetic force, and time-dependent. Nonetheless, their effects on melt pool predictions remain to be understood.

Therefore, the present work analyses those effects systematically through the arc heat flux, the arc pressure, and the electromagnetic force taken one by one. The simulated cases are based on experimental tests with a pulsed gas metal arc that did provide validation data. The obtained results show that these approaches predict thermal flows with significant differences at the free surface and in the melt bulk. They also highlight that the deviations extend beyond the melt pool area underneath the heat source and give rise to significant dissimilarities in melt pool geometry. We conclude by proposing recommendations for the use of these closure approaches. © 2024