Modelling of Turbulent Transport in Laser Melt Pools

In this paper, we present a modified k-ε model capable of addressing turbulent molten metal-pool convection in the presence of a continuously evolving phase-change interface during a laser melting process. The phase change aspects of the present problem are addressed using a modified enthalpy-porosity technique. The k-ε model is suitably modified to account for the morphology of the solid-liquid interface. A three-dimensional mathematical model is subsequently utilised to simulate a typical laser melting process with high power, where effects of turbulent transport can actually be realised. In order to investigate these effects on laser molten pool convection, simulations with laminar transport and turbulent transport are carried out for same problem parameters. Finally, results of the simulation using the present turbulence model are compared with the results of laminar simulation with same problem parameters. Significant effects of turbulent transport on penetration and the geometrical features of the molten pool are observed which is an outcome of the thermal history of the pool. The thermal history in turn determines the microstructure of the work piece, which finally governs the mechanical properties of the work piece.