Interfacial turbulence damping effect on the melt pool dimensions and surface topology during powder bed fusion additive manufacturing

Abstract

A physics-based melt pool turbulence model for a multiphase flow was developed to study the effect of turbulence in a powder-based fusion additive manufacturing process. Two-equation eddy viscosity model which include the Realizable k-ε and the Shear Stress Transport (SST)-k-ω were selected to quantify the turbulence level in the melt pool of powder bed fusion under no interfacial damping. The performance of the two turbulence models was assessed based on their ability to better predict the melt pool dimensions. Further, the interfacial turbulence damping was activated for the best-performing turbulence model to analyze its effect on the melt pool surface topology and dimensions. Assessment of the turbulence level using the turbulent viscosity ratio shows a high turbulence production in the melt pool, and it affects the melt pool dimensions. The analysis shows that the SST-k-ω model’s prediction of the melt pool performs better than the Realizable k-ε model. Subsequent simulations revealed that the interfacial turbulence damping affects the melt pool surface topology and melt pool dimensions. Without interfacial damping, the turbulent viscosity ratio is eleven times greater than its molecular values. An increase in the interfacial damping coefficient decreases the turbulence viscosity ratio, increases the backward flow along the interface, and decreases the melt depth and width. The study reveals new knowledge in the melt pool flow structure, which may be useful for better process control of the powder bed fusion additive manufacturing processes.