par Dalle Vedove, Walter W 
;Sanfeld, Albert
Référence Journal of colloid and interface science, 84, 2, page (318-327)
Publication Publié, 1981-12
;Sanfeld, Albert Référence Journal of colloid and interface science, 84, 2, page (318-327)
Publication Publié, 1981-12
Article révisé par les pairs
| Résumé : | Under nonequilibrium conditions, the coupling between surface chemical reactions and hydrodynamics can induce the onset of convection at an interface between two immiscible Newtonian fluids. A linear analysis of interfacial stability is performed for any number of fluctuating species. The uniform reference steady state is at rest. A nonequilibrium surface elasticity coefficient is defined in terms of the surface relaxation processes. The study is restricted to aperiodic regimes. It is qualitatively and quantitatively shown that unstable and marginal aperiodic regimes can occur only for negative values of the surface elasticity. The instability is due to the self-amplification of the fluctuations of the surface tension. The chemical kinetic conditions necessary for the occurrence of this phenomenon are discussed. Intrinsically (i.e., without convection) unstable-aperiodic regimes with respect to time-surface chemical reactions always induce nonoscillatory unstable mechanochemical regimes, for the same values of the chemical parameters, when these processes are coupled with hydrodynamics. The chemical positive feedback which is responsible for the intrinsic chemical instability is then the fundamental destabilizing factor for the interfacial instability. In the absence of feedback loops in the chemical scheme, unstable mechanochemical regimes are also possible owing to the competition between interfacial chemical and convective processes. The qualitative behavior of the solutions of the dispersion equation is discussed, as well as the roles of the viscosities in the bulk phases and in the surface. New and general stability conditions are obtained. © 1981. |
