Propagation of Surface Tension Changes over a Surface with Limited Area

Abstract

Surface tension changes resulting from a periodic local compression and expansion of a surface propagate over the available surface area. Whether or not the extent of deformation is uniform over the whole area is determined by the value of a dimensionless parameter, the wave propagation number. Uniformity increases with increasingly clastic surface behaviour and with decreasing frequency, area of the surface, and bulk density and viscosity. A number of numerical examples is given. The significance of surface uniformity for the deter mination of the surface dilational modulus and for stability of thin films is discussed.