Thermohydrodynamics analysis of fusion phenomena accompanied with evaporation due to laser irradiation

In microprocessing with laser beam such as laser texturing, quality of processing is influenced significantly by flow of molten pool. It is useful for improvement of processing quality to elucidate both flow of molten pool and mechanism of processing. Theoretical analysis or computer simulation is effective, but there are many problems to be solved in modeling and numerical calculations. One of them is treatment of free surface of molten pool. In this study, a simple method of thermohydrodynamics analysis of molten pool with free surface accompanied with evaporation was proposed. Latent heat of evaporation, movement of gas and liquid interface, evaporation recoil force and surface tension caused by temperature gradient, that is, Marangoni force which accelerates the flow were considered systematically. Free surface of molten pool was treated in this study by introducing VOF method where volume fraction of liquid phase is considered. The present simulation method was applied to the analysis of flow of molten metal in laser texturing.