Title:	CFD simulation of metal transfer and melt pool in additive manufacturing with electric arc
DNr:	SNIC 2021/5-584
Project Type:	SNIC Medium Compute
Principal Investigator:	Isabelle Choquet <isabelle.choquet@hv.se>
Affiliation:	Högskolan Väst
Duration:	2022-01-01 – 2023-01-01
Classification:	20306
Homepage:	https://www.hv.se/personal/isabelle-choquet/
Keywords:

Abstract

This project application on CFD simulation of melt pool and metal transfer in additive manufacturing with electric arc is in the continuation of the SNIC projects 2020/5-674 and 2020/6-274. In this AM process the energy released by a thermal plasma is used to fuse a metal wire, transfer heat and drops to a melt pool in a base metal, and form metal layers upon solidification. To model this process, we developed a CFD solver for free surface thermal flow with solid, liquid and gas phases, capillary and thermocapillary forces in the presence of surfactants, electromagnetic force, and metal transfer. In the last SNIC project this model was applied to study the effect of the base metal orientation on the melt flow and on defect formation (see activity report). The results were presented in an international conference with peer-reviewed publication. We did also comparatively assess several electromagnetic force models currently used. The results were presented in a manuscript submitted to the International Journal of Heat and Mass Transfer. It was concluded that these force models rely on an assumption that should be questioned: the assumption of frozen free surface. The first objective of the proposed project aims at investigating this issue. In that aim, the model will be extended to account for the effect of free surface deformation on the electromagnetic force. As a result, the electromagnetic force will be updated as the free surface will deform, which can significantly increase the computational time. This extended model will be applied to different test cases already studied experimentally at University West. The computational results obtained with the existing and the extended models will be compared, as well as to experimental measurements. The objective is two-fold: analyze the effect on the melt pool flow of assuming a frozen/deforming free surface when computing the electromagnetic force, and evaluate the model ability to capture the physics of the process. In a second part of the proposed project, the solver will be further developed to model the arc pulsation. This development implies temporal and spatial variation of the arc heat flux, arc pressure and current density. A similar evaluation strategy as above described will be applied. It is planned that each part of the proposed project will result in a journal publication. These two publications will contribute to the PhD thesis of Pradip Aryal. To conduct the proposed study, we will keep using OpenFOAM-3.0.1. The test cases will require solving 10 partial differential equations governing scalar fields with a maximum time-step of 1.0e-05 s to reach a final physical time of about 12 s. Based on the former SNIC project, it is evaluated that 5-6 nodes and a minimum of 60 000 core-hours will be needed per simulation. We aim to simulate at least 12 test cases. For this, in total, a minimum computational time of 80 000 core/hours per month for a duration of 1-year will be needed.