# Numerical Simulation of Liquid Film Characteristics during Atomization of Aluminum Alloy Powder
## 1 Introduction  
A light weight is a fundamental quality for materials in the field of aerospace. Firstly, in terms of materials, aluminum alloy, as a typical lightweight metal, is the preferred material in the field of aviation, especially in lightweight aircrafts. The amount of aluminum alloy in civil aircrafts can reach 70-80%, and the amount of high-purity, high-strength, and high-toughness aluminum alloy in military aircrafts is also increasing. In the field of aerospace, aluminum alloy is the main structural material in spacecrafts such as launch vehicles and space stations and is also an important material for missiles and other weapon systems. As the fundamental component of manufacturing technology, the development of better-performing materials is a top priority [1; 2; 3]. As for the advanced manufacturing technology for components, additive manufacturing technology is based on a digital model, which forms parts by \"point-by-point-line-by-layer\" laser melting [4; 5]. With an ultra-high degree of geometric design freedom, model changes are convenient and fast, no mold is required, and the process time is greatly shortened, providing a means of obtaining the ultimate lightweight and integrated structural function design of complex structures in aerospace and other fields [6]. Therefore, aluminum alloy additive manufacturing, by virtue of the material's light weight, structural optimization, integrated design, materialutilization, and other manufacturing advantages, has been widely studied in the field of aerospace structural parts manufacturing. However, at present, aluminum alloy powder for additive manufacturing is mainly prepared by the inert gas atomization method [7]. The poor spherical degree of the powder and its large number of satellite balls and hollow powders greatly limit the additive manufacturing of large-scale, complex, and lightweight structures, representing a major difficulty in the promotion and application of additive manufacturing with aluminum alloy in aerospace and other fields. Therefore, our research group has focused on the development of the preparation technology for high-fluidity aluminum alloy powder for additive manufacturing using rotating disk centrifugal atomization. Compared with the commonly used inert gas atomization powder, the prepared AlSi10 Mg powder reduces the standard geometric deviation of the particle size by approximately 15%, increases the apparent density by approximately 16%, and changes the powder fluidity from 0 to 49.65 s/50 g. Moreover, it has a high sphericity and a smooth surface without satellite powder and hollow powder, and it realizes the preparation of aluminum alloy powder with a high fluidity, a high sphericity, and a high porosity ratio [8]. Through previous research work, the key technical bottleneck involved in the preparation of aluminum metal powder for additive manufacturing by rotating disk atomization has been solved. However, research on the mechanism of rotating disk centrifugal atomization is still relatively lacking, especially regarding the theory and direct industrial application, and the theory and practice are not well combined. This is also the main goal of the present paper. In recent years, with the rapid development of computer hardware and commercial software for computational fluid dynamics (CFD), more and more researchers have used numerical simulation methods to study the breakage processes of liquid films and liquid columns. For example, [PERSON] et al. [9] used the volume of fraction (VOF) model to study the stability of the horizontal jet process and the fracture process of micro-scale liquid columns. [PERSON] et al. [10; 11; 12; 13] used the VOF method to simulate the dynamic characteristics of the gas-liquid two-phase interface during the vertical jet fracture of the liquid filament, and they analyzed the droplet breakage size through numerical simulation. [PERSON] et al. [14] developed the modeling merging and breakup in the moving mesh interface tracking method for multiphase flow simulations [PERSON] et al.