Flow and surface viscosity of insoluble liquid films on supporting liquid surface

Flow of a Newtonian liquid film and the supporting liquid with a longitudin al wave disturbance, which is imparted to the liquid film by means of a sin usoidally oscillating barrier, is numerically simulated in a rectangular tr ough. The effects of surface dilatational viscosity and elasticity of the l iquid film on amplitudes and time lags of tracer particles deposited on the liquid film are investigated. A comparison between the present theoretical results and predictions based on a linear oscillation theory by Maru and W asan (1979 b) indicates that the oscillation of films cannot be expressed b y the simple linear theory, and that the measurement of surface dilatationa l viscosity by the longitudinal wave technique needs a more exact analytica l method, Experiments on the oscillation in a castor oil-water system were carried out. Analysis of the experimental results based on the present theo ry shows that the surface dilatational viscosity of castor oil is Newtonian .