Numerical simulation of nanoparticle dispersion in Al matrix composites under low-frequency oscillating electromagnetic fields

Abstract The present study systematically investigated the cavitation behavior and nanoparticle dispersion in molten aluminum (Al) under low-frequency oscillating electromagnetic forces. A coupled multiphysics numerical model was established, integrating computational fluid dynamics, the revised Schnerr–Sauer cavitation model, and the discrete phase model. The revised cavitation model was validated through comparison with analytical solutions of the Epstein–Plesset equation, thereby confirming its reliability for simulating cavitation in molten Al. The model was subsequently applied to analyze the effects of oscillating electromagnetic force parameters (type, amplitude: 3.09–5.57 × 10 6 N·m −3 , and frequency: 50–300 Hz) on cavitation distribution and nanoparticle dispersion of 1.0 wt.% SiC (30–80 nm). Results demonstrated that the effectiveness of nanoparticle dispersion in the melt depended strongly on cavitation intensity, as both insufficient and excessive vapor volume fractions (VVF) reduced dispersion uniformity. Optimal dispersion occurred at a frequency of 50 Hz and an amplitude of 4.33 × 10 6 N·m −3 , corresponding to a cavitation VVF of approximately 2%, at which cavitation-induced flow reached a maximum without compromising flow stability. Relative to unidirectional excitation, bidirectional oscillating electromagnetic forces produced a more symmetric melt flow field, which facilitated more uniform cavitation and nanoparticle distribution. Increasing the force amplitude enlarged cavitation regions and intensified melt mixing, which improved dispersion, whereas excessively high amplitudes caused cavitation saturation and destabilized the flow. For unidirectional forcing, higher frequencies progressively weakened cavitation by shortening the negative-pressure duration and enhancing the skin effect. By contrast, under bidirectional forcing, increasing frequency initially promoted cavitation through pressure-wave superposition, but subsequently decreased dispersion efficiency owing to insufficient negative-pressure duration and a more pronounced skin effect. The present study may therefore serve as a theoretical basis for the controlled fabrication of nanoparticle-reinforced Al matrix composites via low-frequency electromagnetic processing.