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The traditional Allen–Cahn phase field model doesn't conserve mass and is mostly used in solidification microstructure formation. However, a recently modified Allen–Cahn phase field model has riveted the attention of the academic community. It was obtained by subtracting the curvature‐driven flow term from the advective Allen–Cahn phase field model, and thus improves the boundedness of the phase field. More recently, the model has been further refined with the recovered signed distance function to compute interface normal vectors. This paper develops a three dimensional phase field model, based on the abovementioned Allen–Cahn phase field model. The model was discretized using a finite difference method on a half‐staggered grid. More important, interfacial tension was expressed in a potential form. The model was tested against a number of cases and was applied to impacts in various conditions. Besides, the model was parallelized using the shared memory parallelism, OpenMP, to facilitate computation. [ABSTRACT FROM AUTHOR]

In the drop-on-demand 3D printing technique, molten drop impact is crucial to the understanding of the formation of the building block of a part. However, existing studies cast less due attention to the rebounding dynamics of molten drops. This paper thus develops a phase field method to that end. The model consists of the Cahn-Hilliard equation, coupled with the Navier-Stokes equation to track the evolving liquid-gas interface. A heat source is added to the energy balance equation to distinguish between solid and fluid. The model is discretized using a finite difference method on a semi-staggered grid, and is paralleled based on the shared memory parallelism, OpenMP. The model was first compared with an experiment before being applied to various impacts. The agreement is reasonable. Typical impacts in 3D printing conditions were considered. The major findings are that the Tin drop rebounds off the substrate with a dimpled bottom when the impact velocity is 1 m/s, but with a rounded one when the impact velocity is reduced by half, and that the dimpled bottom is caused by an entrapped bubble during the receding process. Besides, effect of solidification on drop rebounding was examined as well. [ABSTRACT FROM AUTHOR]