Propagation of surface tension changes over a surface with limited area

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 elastic 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 determination of the surface dilational modulus and for stability of thin films is discussed.