Experimental and numerical study of liquid–liquid systems using the Euler–Lagrange/ VOF approach

Achieving stable liquid–liquid dispersions with controlled droplet size remains a challenge due to the complex interplay of dispersed phase viscosity, hydrodynamic conditions and interfacial interactions. This work presents a validated computational framework for droplet breakage and coalescence in liquid–liquid dispersions with variable dispersed‐phase viscosity. The framework couples the Euler–Lagrange approach with the volume of fluid method to track droplet trajectories alongside breakage and coalescence events, and to capture free surface deformation induced by the impeller. Experimental data collected using an EasyMax station with a 300 mL vessel were used to calibrate and validate a newly proposed viscosity‐dependent breakage kernel, alongside evaluation of several pre‐existing coalescence kernels. Model predictions of Sauter mean diameter showed good agreement with experimental measurements across varying stirring speeds, dispersed phase viscosities and concentrations. The resulting framework offers a reliable engineering tool for predicting mean droplet size and guiding the design and scale‐up of stirred dispersion processes.