MD simulation of micro-jetting from grooves with superimposed 3D-perturbations

Shock-driven micro-jetting is vital to high-energy systems, but the role of three-dimensional (3D) surface defects remains unclear. This work presents the first molecular dynamics investigation of micro-jetting from grooves with superimposed 3D perturbations, revealing novel mechanisms of jet evolution and fragmentation that are absent in conventional two-dimensional models. The introduction of 3D perturbations breaks the lateral uniformity assumed in conventional models, significantly altering jet morphology. Longitudinal perturbations promote secondary material convergence and column formation, while transverse perturbations introduce shear and asymmetry, leading to lateral tearing. Combined perturbations result in more complex jet structures and a more uniform mass distribution along the impact direction. Parametric studies show that both the amplitude and wavelength of perturbations influence jet mass and velocity. Notably, when the longitudinal perturbation wavelength is much smaller than the groove wavelength, both the jetting factor and jet velocity are reduced. This could be attributed to multiple reversals in the velocity profile induced by the high-frequency perturbations. Jet breakup behavior is also strongly affected by 3D perturbations, which enhance instability growth and favor the development of columnar structures. Even when initial perturbations are small, preferential void nucleation drives the jet sheet to break into columns, which subsequently fragment into droplets via Rayleigh–Plateau and tensile instabilities. These findings introduce new mechanisms of jet fragmentation and clearly demonstrate the limitations of 2D models, offering new insights for modeling shock-driven ejecta in realistic systems.