Abstract Direct Numerical Simulations are performed to investigate the gas-liquid mass transfer around a rising spherical bubble contaminated by insoluble surfactants. The surfactant transport on the bubble surface and the Marangoni effect are taken into account when solving the hydrodynamics, resulting in the stagnant-cap condition. A parametric study is carried out to investigate the mass transfer by varying the Reynolds, […]

Abstract Planar Laser Induced Fluorescence with Inhibition (PLIF-I) is a powerful technique for studying the local gas/liquid oxygen mass transfer from a single rising bubble. However, to track oxygen in the liquid phase, it is necessary to use an oxygen sensitive luminescent probe, which needs to be unreactive toward the liquid phase. This article presents […]

Abstract This work is an experimental investigation of the effect of the nature of surfactants on oxygen mass transfer. The study focuses on three cationic surfactants with different hydrophobic chain lengths, and four nonionic surfactants with different hydrophilic chain lengths. Equilibrium adsorption isotherms are calculated for each surfactant from experimental values of surface tension in […]

Abstract In this paper, a light absorption method is applied to estimate the thickness of an atomizing liquid film at microscale that exits a spraying nozzle. By using a dioxygen sensitive dye, called resazurin, it is also possible to determine the local profile of dioxygen concentration resulting from the gas-liquid transfer from air into the liquid film. […]

Part I: Bubble dynamics Abstract The investigations of bubble formation dynamics at a cross-junction in a straight milli-channel were reported. The bubble formation process could be divided into the filling and squeezing stages, and their frequencies were compared at various conditions. It was found that the filling and squeezing frequencies were controlled mainly by the […]

Abstract This work is an experimental investigation of the effect of the nature of surfactants on oxygen mass transfer. The study focuses on three cationic surfactants with different hydrophobic chain lengths, and four nonionic surfactants with different hydrophilic chain lengths. Equilibrium adsorption isotherms are calculated for each surfactant from experimental values of surface tension in […]

Ozone is known to be a powerful oxidant with low persistence and has been shown to possess biocidal activity against a wide number of fungi and bacteria. These properties make ozone a good candidate as a substitute for chemical phytosanitary products in agriculture. However, when water containing dissolved ozone is sprayed, the concentration of ozone […]