Thermal Transport Regimes and Generalized Regime Diagram for High Energy Surface Melting Processes

In this study, different thermal transport regimes in high energy surface melting processes are identified by a systematic scaling analysis. It is shown that for a very low Prandtl number, the weld pool morphology is predominantly determined by thermal diffusion, whereas advection plays only a marginal role in determining the shape and size of the molten pool. However, for relatively higher values of the Prandtl number, advective transport in the molten pool may significantly affect the pool shape and size. The criteria, which delineate these two regimes, are estimated by detailed scaling arguments. Based on the scaling analysis, it is demonstrated that turbulence in the molten pool affects the momentum and thermal transport in a distinctive manner. There exists a transport regime in which turbulence may significantly affect the momentum transport in the molten pool, whereas the thermal transport becomes marginally affected by the melt-pool turbulence. A regime diagram is constructed based on the scaling arguments, in which the different thermal transport regimes are clearly indicated for typical high energy surface melting processes.