University of Birmingham > Talks@bham > Applied Mathematics Seminar Series > The role of surfactants on the interfacial stability of multilayer channel flows

The role of surfactants on the interfacial stability of multilayer channel flows

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  • UserAnna Kalogirou, University of Nottingham
  • ClockThursday 23 January 2020, 12:00-13:00
  • HouseBiosciences 301.

If you have a question about this talk, please contact Fabian Spill.

The linear and nonlinear stability of a two-layer surfactant-laden flow in a channel is examined using asymptotic modelling and direct numerical simulations (DNS). The surfactant molecules exist in one of the fluids only but they can get adsorbed at the interface or form micellar aggregates when their concentration is beyond a critical value. A mathematical model is formulated, consisting of governing equations for the hydrodynamics and appropriate transport equations for the surfactant concentration at the interface, the concentration of monomers in the bulk fluid and the micelle concentration. A primary objective of this study is to investigate the effect of surfactants on the stability of the interface, and in particular surfactants in high concentrations and above the critical micelle concentration. Interfacial instabilities are induced due to the acting forces of gravity and inertia, as well as the action of Marangoni forces generated as a result of the dependence of surface tension on the interfacial surfactant concentration. An asymptotic model is also derived in the long-wave approximation, comprising a system of highly nonlinear PDEs describing the evolution of the interface as well as interfacial, bulk and micelle surfactant concentrations. The identified linear instabilities are followed into the nonlinear regime by carrying out numerical computations of the model system as well as DNS . The underlying physical mechanism responsible for the formation of interfacial waves will be discussed, together with the complex flow dynamics (typical nonlinear phenomena associated with interfacial flows include travelling waves, solitary pulses, quasi-periodic and chaotic dynamics).

This talk is part of the Applied Mathematics Seminar Series series.

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