This project application devoted to the computational fluid dynamic (CFD) simulation of metal fusion in welding and additive manufacturing with a laser beam and wire feedstock is in the continuation of the SNIC projects 2022/5-593 (Medium Compute) and 2022/6-347 (Medium Storage) that addressed CFD simulation of metal fusion with an electric arc, and with a laser beam. In these earlier SNIC projects, we developed and applied a model for free surface thermal flow including solid, liquid, and gas phases, thermocapillary and electromagnetic force, and metal transfer in the form of molten droplets. We considered mostly an electric arc as the heat source. We extended the electromagnetic force model to permit its self-adaptation to the deformation of the free surface. Moreover, we comparatively analyzed the different approaches used to model the effect of arc pulsing on the melt pool. The results were submitted for publication in international research journals in 2023. One is now published, and the other is under review. The SNIC projects also contributed to finalizing a Ph.D. thesis that was successfully defended on Oct. 3, 2023. In addition, preliminary studies with a laser beam heat source were also conducted during these SNIC projects, although in the absence of metal transfer. The objective of the proposed project is to extend the above CFD studies of metal fusion with a laser beam to investigate metal deposition from a wire feedstock. This last one is also resistively heated since the electric signals are useful to monitor the process. The continuity of the liquid bridge between the wire and the melt pool is then critical for the stability of the process. However, instabilities occur and their causes are still poorly known. A deeper understanding of this problem is thus needed to better control the process. Therefore, we propose to make use of CFD to investigate the physics taking place in the liquid metal during the necking of the liquid bridge. We will proceed in two steps. We will first assume a laminar flow. Test cases with two metal alloys and three different values of resistive heating will be simulated. We will analyze how changes in process conditions modify the process thermal flow dynamic and liquid bridge stability. Experimental measurements already available will be used for validation. A manuscript for publication in international research journals will also be prepared. If the allocated resources are not all used, a preliminary study will be also conducted on a simplified configuration to evaluate the storage and computation resources needed when considering turbulence. This will permit us to evaluate the resources needed for our future developments. The proposed studies will also include mesh studies to prepare for the above-mentioned test cases. Based on the former projects, it is evaluated that to conduct the proposed project, in total, a minimum computational time of 90 000 core hours per month and storage for at least 11 250 GiB and 10 million files for a duration of 1-year will be needed.