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CFD simulation for AM
CFD simulation for metal Additive Manufacturing: Applications in laser- and sinterbased processes Computational Fluid Dynamics (CFD) is widely applied to solve a broad range of research and engineering problems, from aerodynamics to engine combustion and microfluidics. In this article, Pareekshith Allu, Senior CFD Engineer at Flow Science, Inc, explains how CFD can also be used to improve laser- and non-laser-based metal Additive Manufacturing processes, including Laser Beam Powder Bed Fusion (PBF-LB), Directed Energy Deposition (DED), Binder Jetting (BJT) and Material Extrusion (MEX).
Whether it is the car you drive or the coffee maker you use to brew your morning coffee, chances are you interact every day with a technology that was developed with the help of computational fluid dynamics (CFD). CFD is the study of fluid flow using numerical methods. Since the underlying equations of fluid flow have no analytical solutions, we use computers to solve these equations and simulate fluid interactions in different environments. CFD can be applied to a wide range of research and engineering problems in aerodynamics, engine combustion, water and environmental flows, microfluidics and manufacturing. In this article, I will describe how CFD simulations are used to improve both laser-based and non-laserbased Additive Manufacturing (AM) processes. To begin with, it is important to understand the concept of a free surface flow and, thus, potential free surface flow problems unique to CFD. Free surface flow occurs when two fluids with largely different densities share an interface. Picture a river:
Vol. 6 No. 4 © 2020 Inovar Communications Ltd
a free surface exists between the water and the surrounding air, since the gas/liquid interface is free to move and change with time. Free surface flows are ubiquitous – they span civil engineering applications, microfluidics, and are prevalent throughout manufacturing. In metal casting, for example, a free surface
exists between molten metal and the air in a mould as it’s filled (Fig. 1); in a laser welding process, a free surface molten pool is formed when a laser beam melts and fuses two metal components or parts together. Over forty years ago, the founder of Flow Science Inc., Dr C W Hirt, pioneered a computational technique
Fig. 1 When molten metal fills up a mould, a free surface exists at the interface of the molten metal and the air
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