A 3-D lattice Boltzmann analysis of weld pool dynamic behaviors in plasma arc welding

In this paper, a three-dimensional lattice Boltzmann model is first applied to describe the melting pool evolution in moving plasma arc welding. The heating and key-holing effects of the arc are taken into account by a combined volumetric heat source model. The calculation efficiency is greatly improved by parallel computation. The predicted weld pool geometries with obvious hump agree well with the experimental data, whether for complete joint penetration or not. Several circulations are revealed which colliding with each other at the middle of the fusion lines, and it results in the included angle between the velocity vector and temperature gradient smaller than 90°, along with a quite small velocity. This is considered to contribute to the formation of hump in the fusion line. Finally, a discussion is made on the operational parameters including plasma arc power and welding speed, and we give the optimal prediction based on some different condition simulations. Our study is expected to perform more inherent simulation with LB method and provide appropriate operating parameters to benefit the practical welding production.