Direct Numerical Simulation of droplet formation processes under the influence of soluble surfactant mixtures

• Coupled solution of interfacial surfactant transport equations.
• Surfactant sorption processes.
• Droplet formation processes for droplet profile analysis tensiometry.

The present study is concerned with Direct Numerical Simulation (DNS) of the formation of droplets under the influence of a multicomponent surfactant system, where coupling effects become important. The presented numerical method is based on an Arbitary Lagrangian Eulerian (ALE) interface-tracking method. Collocated second-order Finite Volume/Finite Area methods are employed to discretise the governing equations. Since strong coupling effects among the surfactant species are present, a block-coupled solution procedure is adopted for interfacial surfactant transport. Various sorption models are included. The method is verified by a set of analytical test cases and validated against experimental results regarding droplet formation processes as they are studied in interfacial science in the context of Profile Analysis Tensiometry (PAT) for determination of surface tension.