Laser pulse heating and phase change process: A comparison of volumetric heat source models

Abstract

In the laser heating process, irradiated energy is absorbed on the surface skin of the substrate material. This results in excess computational efforts due to grid arrangement in the irradiated region and the remaining region in the solution domain due to the fine grid spacing in the irradiated region. However, consideration of the surface heat source minimizes this problem, since it does not require fine grid spacing in the skin of the surface. In the present study, laser heating and phase change in the irradiated region are modelled. The laser heating situation is modelled after considering the volumetric heat source incorporating an absorption process (Beer—Lambert's Law) and the surface heat source model. The temperature distribution, melt layer, and solid—liquid zone (mushy zone) formed in the heated region are predicted for the volumetric and surface heat source heating models. This study is extended to include the influence of spatial distribution of the laser pulse on temperature rise and phase change processes. It is found that the surface heat source model predicts higher values of temperature than those corresponding to the volumetric heat source in the surface vicinity. As the depth increases, temperature distributions predicted from both models become almost identical. In addition, the melt layer thickness and mushy zone predicted from both models are almost identical.