Topic
Marangoni effect
About: Marangoni effect is a research topic. Over the lifetime, 5336 publications have been published within this topic receiving 98562 citations. The topic is also known as: Gibbs–Marangoni effect.
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TL;DR: Spontaneous motion of a solid/liquid composite induced by a chemical Marangoni effect, where an oil droplet attached to a solid soap is placed on a water phase, was investigated and showed that the mode of this spontaneous motion switches with a change in the size of the solid scrap.
Abstract: Spontaneous motion of a solid/liquid composite induced by a chemical Marangoni effect, where an oil droplet attached to a solid soap is placed on a water phase, was investigated. The composite exhibits various characteristic motions, such as revolution (orbital motion) and translational motion. The results showed that the mode of this spontaneous motion switches with a change in the size of the solid scrap. The essential features of this mode-switching were reproduced by ordinary differential equations by considering nonlinear friction with proper symmetry.
46 citations
01 Jan 2016
TL;DR: In this article, the authors propose equations of motion for the dynamics of liquid films of surfactant suspensions that consist of a general gradient dynamics framework based on an underlying energy functional, which includes wetting energy, surface energy of the free interface (constant contribution plus an entropic term) and bulk mixing entropy.
Abstract: In this paper we propose equations of motion for the dynamics of liquid films of surfactant suspensions that consist of a general gradient dynamics framework based on an underlying energy functional. This extends the gradient dynamics approach to dissipative non-equilibrium thin film systems with several variables, and casts their dynamic equations into a form that reproduces Onsager's reciprocity relations. We first discuss the general form of gradient dynamics models for an arbitrary number of fields and discuss simple well-known examples with one or two fields. Next, we develop the gradient dynamics (three field) model for a thin liquid film covered by soluble surfactant and discuss how it automatically results in consistent convective (driven by pressure gradients, Marangoni forces and Korteweg stresses), diffusive, adsorption/desorption, and evaporation fluxes. We then show that in the dilute limit, the model reduces to the well-known hydrodynamic form that includes Marangoni fluxes due to a linear equation of state. In this case the energy functional incorporates wetting energy, surface energy of the free interface (constant contribution plus an entropic term) and bulk mixing entropy. Subsequently, as an example, we show how various extensions of the energy functional result in consistent dynamical models that account for nonlinear equations of state, concentration-dependent wettability and surfactant and film bulk decomposition phase transitions. We conclude with a discussion of further possible extensions towards systems with micelles, surfactant adsorption at the solid substrate and bioactive behaviour.
46 citations
TL;DR: In this paper, the authors analyzed the dynamics of the triple gas-liquid-solid contact line for the case where the gas is the saturated vapor corresponding to the liquid and showed that Navier slip alone alone alone is not sufficient to relax the hydrodynamic contact line singularity: the Marangoni term is equally important when the heat transfer is involved.
Abstract: The dynamics of the triple gas-liquid-solid contact line is analyzed for the case where the gas is the saturated vapor corresponding to the liquid. For partial wetting conditions, a nonstationary contact line problem where the contact line motion is caused by evaporation or condensation is treated. It is shown that the Navier slip condition alone is not sufficient to relax the hydrodynamic contact line singularity: the Marangoni term is equally important when the heat transfer is involved. The transient heat conduction inside the heater is accounted for. A multiscale problem of drop evaporation with freely moving contact line is solved in the lubrication approximation as an illustration of the proposed approach.
45 citations
TL;DR: In this article, a fundamental study on the movement of various sized micro-liter droplets on a surface subjected to temperature gradients is presented, where the histories of droplet movement are recorded by high-speed CCD camera and are simulated by numerical methods based on first principle equations.
Abstract: This work is a fundamental study on the movement of various sized micro-liter droplets on a surface subjected to temperature gradients The histories of droplet movement are recorded by high-speed CCD camera and are simulated by numerical methods based on first principle equations The agreement between computations and experimental observations are obtained The study indicates that temperature gradients, the change of dynamic receding/advancing contact angles across the droplets, and the flowfields inside the droplet are the key parameters determining the moving behavior of the micro-droplet driven by Marangoni and capillary effects
45 citations
TL;DR: It was found that water droplets on an aluminum surface exhibit a 'depinning jump' at subatmospheric pressures, thought that the local concentration of the surfactant causes a gradient of surface tension.
45 citations