Numerical simulation of surfactant-laden emulsion formation in an un-baffled stirred vessel

The present study aims to elucidate the interplay among the interfacial dynamics, surfactant transport, and underlying flow structures inside a cylindrical stirred vessel equipped with a pitched blade turbine. To address this, massively parallel three-dimensional, interface-tracking, large eddy simulations of oil-in-water dispersions are deployed to provide detailed, realistic visualisations of the intricate interfacial dynamics coupled to the turbulent flow field. In particular, we isolate the effect of surfactant arising from interfacial tension reduction and Marangoni stress (related to surfactant concentration gradient) by comparing two surfactant-laden systems, one being a realistic and experiment-achievable case, and another a simulation-exclusive system where the Marangoni stress is turned off. This comparison consists of qualitative interface visualisation as well as quantitative statistics in terms of dispersed phases counts and their size distribution. Finally, surfactant elasticity is modified with the aim of exploring its effect on the targeted mixing system.