Surface wave scattering at nonuniform fluid interfaces

TL;DR

This paper investigates how spatial variations in surface properties affect surface wave propagation and scattering at fluid interfaces, highlighting mechanisms for wave attenuation and potential experimental detection methods.

Contribution

It introduces a theoretical framework for analyzing surface wave scattering due to inhomogeneities using Green's functions and the Born approximation, considering mode coupling effects.

Findings

Surface inhomogeneities cause wave scattering and attenuation.

Mode coupling influences wave propagation when viscosity and elastic moduli vary.

Theoretical predictions suggest experimental detection of scattering and attenuation.

Abstract

Effects of spatially varying interfacial parameters on the propagation of surface waves are studied. These variations can arise from inhomogeneities in coverage of surface active substances such as amphiphillic molecules at the fluid/gas interface. Such variations often occur in phase coexistence regions of Langmuir monolayers. Wave scattering from these surface inhomogeneities are calculated in the limit of small variations in the surface parameters by using the asymptotic form of surface Green's functions in the first order Born approximation. When viscosity and variations in surface elastic moduli become important, modes other than transverse capillary waves can change the characteristics of propagation. Scattering among these modes provides a mechanism for surface wave attenuation in addition to viscous damping on a homogeneous surfactant covered interface. Experimental detection of waves attenuation and scattering is also discussed.