Phase relaxation of Faraday surface waves

Surface waves on a liquid-air interface excited by a vertical vibration of a fluid layer (Faraday waves) are employed to investigate the phase relaxation of ideally ordered patterns. By means of a combined frequency-amplitude modulation of the excitation signal a periodic expansion and dilatation of a square wave pattern is generated, the dynamics of which is well described by a Debye relaxator. By comparison with the results of a linear theory, it is shown that the measured relaxation time allows a precise evaluation of the phase diffusion constant.