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Tandemproject Dr. Thomas Boeck (TU Ilmenau) and Dr. Kerstin Eckert (TU Dresden)

A combined experimental and numerical approach to study the hierarchy of multi-scale structures arising from the stationary solutal Marangoni instability

Mass transfer across liquid interfaces is frequently accompanied by solutal Marangoni convection with complex and irregular flow structures. This so-called interfacial turbulence is of considerable importance in chemcial engineering. Interfacial turbulence is known to evolve progressively from small to large lengthscales by a cascade-like process. This hierarchical evolution displays a characteristic sequence of flow structures before it is repeated on a significantly larger length scale. The details of this evolution and the characteristic properties of the various flow structures and their transformations are only poorly understood. These deficiencies will be addressed by the project through a combination of accurate experiments with novel techniques for optical flow measurement, and by highly resolved numerical simulations. The particular configuration to be studied is a liquid-liquid system, composed of two immiscible solvents separated by a plane interface. The mathematical model incorporates the flow in both liquid phases in connection with a separate transport equation of the interfacial concentration and takes a nonlinear sorption kinetics of the surfactant into account. Relevant data to the generic structures of interfacial turbulence at a plane interface will be provided to other projects of the priority programme in benchmark quality.