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: It is found that surfactant contamination, at a surface concentration as small as 300 molecules/microm(2), can almost entirely suppress the Marangoni flow in the evaporating droplet.
Abstract: We study the effects of Marangoni stresses on the flow in an evaporating sessile droplet, by extending a lubrication analysis and a finite element solution of the flow field in a drying droplet, developed earlier.1 The temperature distribution within the droplet is obtained from a solution of Laplace's equation, where quasi-steadiness and neglect of convection terms in the heat equation can be justified for small, slowly evaporating droplets. The evaporation flux and temperature profiles along the droplet surface are approximated by simple analytical forms and used as boundary conditions to obtain an axisymmetric analytical flow field from the lubrication theory for relatively flat droplets. A finite element algorithm is also developed to solve simultaneously the vapor concentration, and the thermal and flow fields in the droplet, which shows that the lubrication solution with the Marangoni stress is accurate for contact angles as high as 40°. From our analysis, we find that surfactant contamination, at a...
803 citations
TL;DR: In this article, a Fourier series method has been used to obtain the eigenvalue equation for the case where the lower boundary surface is a rigid conductor and the upper free surface is subject to a general thermal condition.
Abstract: The cells observed by Benard (1901) when a horizontal layer of fluid is heated from below were explained by Rayleigh (1916) in terms of buoyancy, and by Pearson (1958) in terms of surface tension. These rival theories are now combined. Linear perturbation techniques are used to derive a sixth-order differential equation subject to six boundary conditions. A Fourier series method has been used to obtain the eigenvalue equation for the case where the lower boundary surface is a rigid conductor and the upper free surface is subject to a general thermal condition. Numerical results are presented. It was found that the two agencies causing instability reinforce one another and are tightly coupled. Cells formed by surface tension are approximately the same size as those formed by buoyancy. Benard's experiments are briefly discussed.
552 citations
TL;DR: It is demonstrated that the Marangoni flow can significantly influence the resulting patterns of particle deposition in the face of nonuniform evaporation.
Abstract: Nonuniform evaporation from sessile droplets induces radial convection within the drop, which produces the well-known ‘‘coffee-ring’’ effect. The evaporation also induces a gradient in temperature and consequently a gradient in surface tension, generating a Marangoni flow. Here we investigate theoretically and experimentally the thermal Marangoni flow and establish criteria to gauge its influence. An asymptotic analysis indicates that the direction of the flow depends on the relative thermal � ;
526 citations
TL;DR: In this paper, the authors report another example of such unstable driven flow, this time caused by the Marangoni effect, in which a temperature gradient induces a gradient of surface tension which drives the spreading process.
Abstract: THE dynamics of spreading of thin liquid films are important to many technological and biological processes, including tertiary oil recovery, coating processes, the formation and protection of microchips and biological cell interactions. The spontaneous spreading of thin liquid films under capillary forces alone is typically a slow process. An applied force—gravitational or centrifugal, or a surface shear stress—can be used to drive the spreading more quickly1,2. Recent experimental3,4 and theoretical5 studies have revealed that in all of these cases of forced spreading, the liquid front undergoes a fingering instability. Here we report another example of such unstable driven flow, this time caused by the Marangoni effect6, in which a temperature gradient induces a gradient of surface tension which drives the spreading process.
385 citations
TL;DR: A comprehensive review of numerical methods and models for interface resolving simulations of multiphase flows in microfluidics and micro process engineering is presented in this paper, where three common approaches in the sharp interface limit, namely the volume-of-fluid method with interface reconstruction, the level set method and the front tracking method, as well as methods with finite interface thickness such as color function based methods and the phase-field method are discussed.
Abstract: This article presents a comprehensive review of numerical methods and models for interface resolving simulations of multiphase flows in microfluidics and micro process engineering. The focus of the paper is on continuum methods where it covers the three common approaches in the sharp interface limit, namely the volume-of-fluid method with interface reconstruction, the level set method and the front tracking method, as well as methods with finite interface thickness such as color-function based methods and the phase-field method. Variants of the mesoscopic lattice Boltzmann method for two-fluid flows are also discussed, as well as various hybrid approaches. The mathematical foundation of each method is given and its specific advantages and limitations are highlighted. For continuum methods, the coupling of the interface evolution equation with the single-field Navier–Stokes equations and related issues are discussed. Methods and models for surface tension forces, contact lines, heat and mass transfer and phase change are presented. In the second part of this article applications of the methods in microfluidics and micro process engineering are reviewed, including flow hydrodynamics (separated and segmented flow, bubble and drop formation, breakup and coalescence), heat and mass transfer (with and without chemical reactions), mixing and dispersion, Marangoni flows and surfactants, and boiling.
378 citations