Numerical Analysis of Effect of Different Initial Morphologies on Molten Pool Flows

The different initial morphologies of polished surface is one of the important factors affecting the quality of laser polishing. In order to investigate the flow characteristics of the molten pool with different morphologies, a two-dimensional (2D) axisymmetric numerical model is established based on the COMSOL software. The nonisothermal flow interface is used to couple the heat transfer and fluid flow, and simulate the evolution process of the molten pool with three different surface morphologies. The results show that the initial shape is a smooth plane, the flow velocity of the molten pool is stable and always in thermocapillary regime, then the protrusions were generated at the edge of the molten pool. Likewise, with the increase of the surface curvature, the capillary becomes the main driving force to eliminate the surface asperities. While the flow velocity and instability of the molten pool enhance, and the depth of the molten pool increases with the heat transfer generated by the mass flow along the z-axis direction.