Pattern in Marangoni-Instability Varied by Shear Stress Between Interface and Bulk
Pattern formation and selection by selforganization is one of the most fascinating nonlinear mechanisms due to irreversible processes with internal feedback. Interfacial dynamic instabilities like Marangoni-instability show a surprising variety of different kinetic regimes and the corresponding pattern formating dissipative structures /1/, including patterns of stationary simple or hierarchically substructured systems, classical (mechanical) oscillations with wave interference patterns and relaxation oscillation with autowave patterns too. These stationary as well as moving patterns can easily be influenced and even extended by coupling with further different driving forces. For instance, the old spectacular results of Benard’s experiments are caused by coupling of Rayleigh-instability with Ma-instability. That means, that the buoyancy forces in the unstable gradient of density are cooperating with interfacial tension forces by heat transfer and/or mass transfer of surface active matter. The last is easily realizable in two component liquids consisting of a quickly evaporating liquid of small surface tension and a slowly or not evaporating liquid respectively a soluted component with a higher surface tension. Heat transfer alone by heat conduction or in the consequence of evaporation cooling is also able to realize conditions of Ma-instability.
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