Julien Landel
Laboratoire de Mécanique des Fluides et d’Acoustique, Polytech Lyon – Université Claude Bernard Lyon 1
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Impact of confinement on solutal Marangoni driven flows
In this presentation we will discuss flow phenomena related to the impact of geometrical confinement in surfactant-driven Marangoni flows at liquid surfaces. The Marangoni effect is due to out-of-equilibrium surfactant concentrations at liquid-gas interfaces. The resulting gradient in surface tension leads to shear stresses at interfaces and flow entrainment of the bulk liquid. Surfactant molecules have been described as ‘hidden variables’ by Manikantan and Squires in their 2020 JFM Perspectives article, owing to their substantial impact on macroscale flows whilst evading simple measurements or observations. With three examples of fluid flow phenomena, we will see how surfactants can: disrupt the drag reducing performance of superhydrophobic surfaces; solve a liquid maze, and how this might help understanding surfactant-based treatment for some lung diseases; and finally, how surfactants may be the clue to the Japanese art of Suminagashi. Through laboratory experiments, theoretical modelling and numerical simulations, we will explore the effects of these hidden variables.
