Li Chunxi

Notice of Retraction Non-uniform spreading of soluble surfactant solutions with disjoining pressure

To analyze the effect of disjoining pressure for the soluble surfactant spreading process of a non-uniform thin film, the present paper establishes a 3-equations mathematical model and derives nonlinear evolution equations of the film thickness, surface monomers concentration and bulk monomers concentrations in the lubrication approximation. Additionally, this paper investigates a candidate mechanism that could create and drive this instability, disjoining pressure rupture, via numerical simulations coupled with analytical techniques. The evolutional profiles and transport characteristics of a drop spreading are investigated.

Notice of Retraction Spreading of soluble surfactant solutions over a thin aqueous layer on isothermal solid substrate

The spreading of a drop of soluble surfactant over thin aqueous layer in the presence of isothermal heating is considered. Use of lubrication theory yields a coupled pair of partial differential equations for the film thickness, surface and bulk surfactant concentrations. The numerical results by the PDECOL procedure show that droplet patterns are obtained under the isothermal conditions of underlying substrate. The effects of variation of Marangoni parameter and air-liquid Biot number are examined. Decreasing Marangoni parameter leads to flatter drop peak and longer time to rupture. Decreasing the air-liquid Biot number flattens the film thickness and surfactant concentration profile of the drop. In all situations the surfactant is found to rigidify the air-liquid interface, while the thermal capillary acts to destabilize the film.