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.

Onset of solutal Marangoni convection in a suddenly desorbing liquid layer

Abstract: The onset of surface-tension-driven convection in an initially quiescent liquid layer experiencing sudden desorption from a free surface is analyzed using the linear stability theory. The propagation theory was developed for the basic time-dependent concentration profile, which is strongly nonlinear. Based on this theory, a new set of stability equations is derived in considering the effect of Gibbs adsorption and by neglecting the surface diffusion. It is found that the liquid layer becomes more stable by decreasing the Schmidt and Biot numbers. It is interesting that, during an initial period, the system is stable, depending on the Gibbs effect. The predictions agree favorably with the existing experimental results of triethylamine desorption in water in a wetted-wall and a liquid-jet column.

Dispersion of water into oil in a rotor–stator mixer. Part 1: Drop breakup in dilute systems

Abstract: Most previous studies of liquid–liquid dispersion in complex geometry are limited to turbulent flow at low continuous phase viscosity. In this study, a viscous continuous phase was employed over a range of flow conditions including both the laminar and turbulent regimes. Equilibrium drop size was measured for water dispersed into viscous food grade mineral oils in a batch Silverson L4R rotor–stator mixer. The influence of fluid viscosities and interfacial tension (by adding an oil-soluble surfactant) were examined. In order to isolate the effect of drop breakage from coalescence, Part 1 is limited to dilute conditions (water phase fraction, ϕ = 0.001). In the laminar regime, drop breakup was more likely due to a simple shear breakage mechanism than one for extension. Following Grace (1982) , a semi-empirical drop size correlation was developed. For turbulent flow, the validity of the sub-Kolmogorov inertial stress model for correlating equilibrium mean drop size was verified. Surfactants were found to mostly decrease drop size by lowering interfacial tension. Except for laminar systems near the critical micelle concentration, where Marangoni stresses appear to play some role, the effect of surfactants on the drop size could be correlated using the equilibrium or static interfacial tension. The influence of water phase fraction and coalescence is considered in Part 2 ( Rueger and Calabrese, 2013 ) of this paper.

Thermal management with self-rewetting fluids

Abstract: The present paper describes the results of a series of microgravity experiments on thermal management device, actually wickless heat pipes, with using the so-called “self t-rewetting fluids” (dilute aqueous solutions of high carbon alcohols) as a working fluid. Although most of liquids show a decrease in the surface tension with increasing temperature, self-rewetting fluids show exceptionally an increase in the surface tension with increasing temperature. This particular characteristic allows for a spontaneous liquid supply to hotter interface by the thermocapillary flow. When liquid/vapor phase change takes place, furthermore, additional Marangoni effect due to concentration gradient by the preferential evaporation of alcohol-rich composition in the aqueous solutions is induced. A considerably strong liquid inflow to dry patch or thin film is therefore expected at three-phase interline or liquid/vapor interface. One of the most promising applications of the self-rewetting fluids in space is wickless heat pipes in which condensate spontaneously returns to evaporation region by enhanced Marangoni effect. Demonstrational experiments on the fluid behavior in a transparent glass tube wickless heat pipe were conducted in JAMIC, and spontaneous liquid return velocities were measured. The present authors then performed parabolic flight experiments on heat transfer characteristics of prototype wickless copper heat pipes, and the performance was compared with ordinary heat pipe having wick structure and with other working fluid.