Interfacial Hydrodynamics: An Over View

Abstract

A fluid interface may promote spontaneous flow, or, particularly if laden with a surface-active agent, may act to suppress flow in its vicinity. In either event, the effect is the result of locally unbalanced forces at the interface. The resulting flows may be chaotic (interfacial turbulence) or orderly (cellular convection), steady, periodic or intermittent. They may significantly increase heat and mass transfer rates and alter contacting patterns in fluid-phase contacting equipment. Flow suppression due to surface-active agents may also assume a variety offorms and may significantly reduce transfer rates. These phenomena are classified, illustrated and rationalized in terms of hydrodynamic theory. Recent research developments and implications for metallurgical systems are given. Resume-Uneinterface fluide peut generer un ecoulement spontane, ou, si elle est recouverte par un agent tensio-actif, supprimer cet ecoulement. Dans les deux cas, l'effet observe est dfI a des forces locales non equilibrees it l'interface. Les ecoulements resultants peuvent etre irreguliers (turbulence interfaciale) ou ordonnes (convection localisee), stables, periodiques ou intermittents. Ils peuvent augmenter de fa<;on appreciable les taux de transfert de masse et de chaleur et modifier la nature du contact du fluide avec les equipements. Les agents tensio-actifs modifient grandement les profils des ecoulements et peuvent reduire de fa<;on marquee les taux de transfert de masse et de chaleur. Tous ces differents phenomenes sont classifies, illustres et analyses it l'aide de la theorie de l'hydrodynamique des fluides. De nouveaux developpements de recherche ainsi que les implications pour les systemes metallurgiques sont presentes.

Fabrication of PLGA nanoparticles with a fluidic nanoprecipitation system

“…Consequently, the size of the final particle will be influenced not only by features of the dispersing channel related to Reynolds number, but also by factors that influence interfacial tension. These include the polymer concentration, the presence and concentration of surfactant [ 37 ], and the nature of any payload that is co-precipitated into the particles [ 37 ]. The depth of insertion of the inlet into the dispersing channel might also influence particle size and geometry due to altered turbulence.…”