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This paper validates three-dimensional (3D) simulation results of electron beam melting (EBM) processes by comparing experimental and numerical data. The physical setup is presented which is discretized by a 3D thermal lattice Boltzmann method (LBM). An experimental process window is used for the validation depending on the line energy injected into the metal powder bed and the scan velocity of the electron beam. In the process window, the EBM products are classified into the categories, porous, good and swelling, depending on the quality of the surface. The same parameter sets are used to generate a numerical process window. A comparison of numerical and experimental process windows shows a good agreement. This validates the EBM model and justifies simulations for future improvements of the EBM processes. In particular, numerical simulations can be used to explain future process window scenarios and find the best parameter set for a good surface quality and dense products.

We studied dip formation phenomena in a draining water tank using the model of sink arrays. As the parameter for the drain size r increases, the effective Froude number F_eff is found to decrease according to F_eff/F=r^-∊ where F is the Froude number defined as F=q₀/[2π(gh³)^1/2] and ∊ is a constant. Here, q₀ is the total sink strength, h is the submerged depth of the sink array, and g is the gravitational acceleration. For F=0.286, ∊ is found to be ∊ ≈ 0.44. The implications of the results are discussed.