Effect of light-actuated photosurfactants on the stability of a viscous thread

This talk investigates the effects of a light-actuated photosurfactant on the canonical problem of the stability of a viscous thread supported by a liquid of negligible viscosity. A model consisting of the Navier-Stokes equations and a set of molar concentration equations is presented that capture light-induced switching between two stable surfacant isomer states, trans and cis. These two states display significantly different interfacial properties, allowing for some external control of the stability behaviour of the thread via incident light. Details on the impact of this light on the linear stability of the thread are discussed. Furthermore, to validate our solution method, we compare our solutions with analytical solutions of increasing complexity, while on the way providing a holistic discussion of the effect of surfactants in general on the stability of a liquid thread.