Abstract Summary (Max 250 words)
Hydrodynamic cavitation (HC) has evolved from a destructive phenomenon into a potent tool for process intensification, particularly for energy-efficient emulsification. While linear devices like venturi tubes are widely used, they require relatively higher pressure drop for cavitation inception and their operating life is often limited because of erosion induced by cavitation near solid walls. In contrast, the vortex-based cavitation devices (VD) utilize a tangential inlet to generate a strong vortex leading to early inception of cavitation and creating a cavitation zone away from solid walls. In this work we computationally investigate and elucidate the multiscale mechanisms driving oil droplet deformation and breakup in VD. This study employs a Large-Eddy Simulation (LES) approach coupled with a hybrid Volume of Fluid (VOF) and Discrete Phase Model (DPM) framework. This hybrid strategy combines VOF to resolve the transient deformation of the primary droplet interface on the finite volume grid, with DPM to track the dynamics of sub-grid liquid fragments post-breakup. The research investigates the influence of the Weber number on transient deformation topologies, specifically analyzing the transition from VOF-resolved ligaments to DPM-tracked daughter droplets. Results reveal that the complex interplay of anisotropic turbulence and pressure gradients within the vortex core drives critical deformation, leading to distinct sub-droplet size distributions. This comprehensive analysis provides new insights into the dynamics of emulsification under cavitation conditions. The presented approach, model and results provide a sound basis for understanding emulsification in VDs and thereby expand their applications to emulsification and other multiphase processes.
