Abstract

Hydrodynamic cavitation is increasingly applied to emulsification and homogenization because cavity growth and collapse generate intense, localized pressure gradients, microjets, and turbulent dissipation within continuous flow equipment. This article examines the coupled hydraulic, interfacial, and kinetic mechanisms governing droplet breakup and stabilization and reviews the principal models used to describe cavitation assisted emulsification. Static constrictions, Venturi devices, vortex reactors, and dynamic rotor stator systems are evaluated with respect to cavitation regime, pressure recovery, residence time, energy input, and product response. Emulsion quality is treated as a distributional problem rather than a single mean diameter, with emphasis on Sauter mean diameter, coarse droplet tails, interfacial area, recoalescence, and storage stability. The analysis covers Kolmogorov and Hinze scaling, Rayleigh collapse relations, the Kozyuk and Fedotkin bubble field model, population balance methods, and reduced order descriptions, together with their assumptions and validation requirements. Published results are considered for vegetable oils, proteins, dairy systems, cosmetics, pharmaceuticals, fuels, and specialty chemical applications. Particular attention is given to backpressure, pass number, viscosity, phase fraction, emulsifier concentration, temperature, dissolved gas, erosion, sanitation, scale up, and process control. The evidence indicates that maximum visible cavitation does not necessarily correspond to optimum homogenization. Industrial performance is better defined by a validated operating window that couples droplet size distribution and stability with throughput, energy, thermal history, chemical quality, cleanability, and equipment durability.

Keywords: hydrodynamic cavitation; emulsification; homogenization; droplet breakup; cavitation reactor; population balance; scale up