Multiphysics Simulation of Melt Pool Evolution in Directed Energy Deposition Additive Manufacturing

Abstract

Directed Energy Deposition (DED) is a metal additive manufacturing process widely used for near-net-shape fabrication, repair of high-value components, and production of large-scale metallic structures. The quality of DED-built parts strongly depends on the thermal history, melt pool geometry, and layer-by-layer heat accumulation during deposition. Therefore, numerical simulation is an effective tool for understanding the process physics and supporting parameter selection before experimental manufacturing. In this study, a three-dimensional multiphysics model was developed to simulate the DED process using COMSOL Multiphysics. The model couples heat transfer, laminar fluid flow, and solid mechanics to evaluate the thermal and physical behavior of deposited metallic layers. A moving Gaussian laser heat source was implemented to represent laser-material interaction, while the governing equations of energy, momentum, and mass conservation were solved to predict temperature distribution and melt pool formation. A symmetric computational domain consisting of a base plate and three deposited powder layers was designed. Steel AISI 4340 was selected as the model material, and its thermophysical properties were incorporated into the simulation. The results show that the proposed model can capture the transient temperature distribution and melt pool evolution during successive layer deposition. The findings indicate that heat accumulation from previously deposited layers significantly affects the thermal field and melt pool characteristics in subsequent layers. The simulation also demonstrates that a coupled multiphysics approach provides deeper insight into the interaction between laser heating, melt pool development, and thermal deformation. The developed model can be used as a practical framework for understanding DED process behavior and supporting future process parameter optimization studies.

Keywords

• Additive manufacturing
• Directed energy deposition
• COMSOL Multiphysics
• Melt pool
• Numerical simulation

Ethical Statement

Ethics committee approval was not required for this study because of there was no study on animals or humans.

References

1. Ansari, P., & Salamci, M. U. (2022). On the selective laser melting based additive manufacturing of AlSi10Mg: The process parameter investigation through multiphysics simulation and experimental validation. Journal of Alloys and Compounds, 890, Article 161873. https://doi.org/10.1016/j.jallcom.2021.161873
2. Ansari, P., Rehman, A. U., Pitir, F., Veziroglu, S., Mishra, Y. K., Aktas, O. C., & Salamci, M. U. (2021). Selective laser melting of 316L austenitic stainless steel: Detailed process understanding using multiphysics simulation and experimentation. Metals, 11(7), Article 1076. https://doi.org/10.3390/met11071076
3. Chung, M., Lee, K. H., Park, J., Lee, Y. S., & Yun, G. J. (2025). A fully computational approach for the prediction of melt pool generation of the directed energy deposition process. Journal of Mechanical Science and Technology, 39(1), 1–16. https://doi.org/10.1007/s12206-025-1029-0
4. COMSOL AB. (2022). COMSOL Multiphysics (Version 6.1). https://www.comsol.com
5. Duan, C., Cao, X., Luo, X., Shang, D., & Hao, X. (2023). Multi-physics investigations on the gas-powder flow and the molten pool dynamics during directed energy deposition process. Journal of Manufacturing Science and Engineering, 145(8), Article 081008. https://doi.org/10.1115/1.4062259
6. Guo, J., Wang, Z., Wang, Z., Xu, Z., Peng, S., & Wang, F. (2025). Research on the coupled characteristics of multi-physics fields in direct energy deposition melt pool considering powder effect. International Journal of Heat and Mass Transfer, 246, Article 127074. https://doi.org/10.1016/j.ijheatmasstransfer.2025.127074
7. Jia, Y., Jegou, L., Feulvarch, E., Saadlaoui, Y., Kaftandjian, V., Elguedj, T., Dubar, L., & Bergheau, J. M. (2024). An improved Arbitrary Lagrangian–Eulerian thermal-fluid model by considering powder deposition effects on melting pool during Direct Energy Deposition processes. Additive Manufacturing, 96Trace, Article 104570. https://doi.org/10.1016/j.addma.2024.104570
8. Khairallah, S. A., Chin, E. B., Juhasz, M. J., Dayton, A. L., Capps, A., Tsuji, P. H., Bertsch, K. M., Perron, A., Mccall, S. K., & Mckeown, J. T. (2023). High fidelity model of directed energy deposition: Laser-powder-melt pool interaction and effect of laser beam profile on solidification microstructure. Additive Manufacturing, 73, Article 103684. https://doi.org/10.1016/j.addma.2023.103684

9. Liu, W., Liu, H., Li, W., Liu, B., Ma, Z., Song, J., Wang, T., Wang, L., & Chang, Y. (2024). Investigation of molten pool geometry and flow field based on powder-scale modeling in laser directed energy deposition. The International Journal of Advanced Manufacturing Technology, 134(9), 4253–4270. https://doi.org/10.1007/s00170-024-14344-7
10. Zhang, L., Chen, J., Gao, X., Niu, F., & Zhang, Z. (2024). Gas-particle-heat dynamic coupling simulation in directed energy deposition. International Journal of Mechanical Sciences, 275, Article 109302. https://doi.org/10.1016/j.ijmecsci.2024.109302