Numerical investigation of the nano-scale solutal Marangoni convections

Marangoni convection driven by surface tension gradient plays an important role in nano-scale processes and also the processes under microgravity in space, where the effect of surface tension may become significant compared with that of the gravitational body force. For a better understanding of Marangoni convection occurring in a nano-scale process, Molecular Dynamics (MD) and Computational Fluid Dynamics (CFD) simulations were carried out for a thin liquid film with concentration gradient. The computed flow structures by these methods were compared. The results show quantitative differences in the magnitudes of the flow velocity and the deformation of the liquid film. It was also found that a stronger driving force would be needed to generate nano-scale flows compared with that required for macro-scale flows. This is due to the fact that a stronger surface force may be needed to overcome the random movements of molecules.