Abstract
Acoustic properties of porous material are slightly changed by a coating layer, which is thin compared to the acoustic wavelength. These changes affect mainly the spherical wave reflection coefficient at grazing incidence. The phase change of a surface wave component is observed and enables the easy detection of the thin layer by measuring the interference of direct and guided surface waves. This method is investigated for screening observations in order to monitor liquid pollutants on marine sediment. Since sediment is usually not plain but more or less irregularly grooved, the coating by liquid pollutants will occur in patches. Laboratory experiments are carried out with rough surfaces of sediment to investigate the sensitivity of detecting an average change in impedance. The results are compared with a numerical model incorporating Biot theory [Tooms et al., J. Acoust. Soc. Am. 93, 171–181 (1998)], which was successfully applied to model experimental data of plain sediment (Harms et al., 134th meeting of ASA). Since the rough surface produces a significant backscattering, the liquid patches are detectable in the backscattered signal as well. Experimental results of this contribution are presented and the possibility of using this method for monitoring purposes discussed. [Work supported by German Ministry of Technology BMFT.]
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
