eng URI http://hdl.handle.net/10795/3385 physical sciences applied research university research The analysis for the physical mechanism of the long-wave instability in liquid film flow is extended to take into account the presence of a surfactant of arbitrary solubility. The Navier–Stokes equations are supplemented by mass balances for the concentrations at the interface and in the bulk, by a Langmuir model for adsorption kinetics at the interface, and are expanded in the limit of long-wave disturbances. The longitudinal flow perturbation, known to result from the perturbation shear stress which develops along the deformed interface, is shown to contribute a convective flux that triggers an interfacial concentration gradient. This gradient is, at leading order, in phase with the interfacial deformation, and as a result produces Marangoni stresses that stabilize the flow. The strength of the interfacial concentration gradient is shown to be maximum for an insoluble surfactant and to decrease with increasing surfactant solubility. The decrease is explained in terms of the spatial phase of mass transfer between interface and bulk, which mitigates the interfacial flux by the flow perturbation and leads to the attenuation of Marangoni stresses. Higher-order terms are derived, which provide corrections for disturbances of finite wavelength. 17 pp. LOMv1.0 creator LOMv1.0 publisher LOMv1.0 Project Executing Organisation 2014 Digital Library of the Operational Programme "Education and Lifelong Learning" abstract types Text Instability Interfacial flows (free surface) Marangoni convection 340776 application/pdf http://repository.edulll.gr/edulll/bitstream/10795/3385/2/3385_JFM_paper2.pdf Πανεπιστήμιο Θεσσαλίας. Τμήμα Μηχανολόγων Μηχανικών. - Δημοσιεύσεις. URI http://hdl.handle.net/10795/3385 LOMv1.0creator 2016-05-25T07:25:56Z LOMv1.0validator 2016-05-25T07:25:56Z LOMv1.0 gre no no Copyright EYD-EPEDBM (Operational Programme "Education and Lifelong Learning")