What is it about?

We study the spreading dynamics of an insoluble and non-diffusive surfactant on the free surface of a deep layer of a Carreau fluid. When a non-uniform distribution of surfactant is imposed on the free surface of an initially motionless fluid, variations in surface tension are induced, causing the fluid motion from regions of lower surface tension to those of higher tension. Such movement redistributes the surfactant concentration until a uniform condition is reached.

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Why is it important?

The present work focuses on determining how the convective effects and the inertia of the flow affect the surfactant distribution on the free surface of a deep fluid layer initially motionless, where the Carreau model describes the fluid rheology. The results show that the temporal decay of the surfactant concentration on the fluid surface increases significantly for high values of the Reynolds number, it is more attenuated in pseudoplastic fluids than in Newtonian fluids, and the surfactant concentration decay exhibits asymmetric oscillations when inertial effects increase.


Non-Newtonian fluids have great importance in this type of phenomenon, and it is of great interest to know how surfactants influence the fluid flow structure, the implications of rheology on the involved phenomenon, and the surfactant evolution on the fluid interface.

Dr. Lorenzo Martínez-Suástegui
Instituto Politecnico Nacional

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This page is a summary of: Oscillatory Marangoni flow in a deep layer of a Carreau fluid, Physics of Fluids, April 2023, American Institute of Physics,
DOI: 10.1063/5.0144235.
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