Increased interest in high frequency sonar operations in surf and nearshore zones requires a knowledge of the acoustic properties of the sea bottom and leads to study high frequency acoustic wave reflection on a recently settled sediment paricularly at low grazing insonification angles. In this paper, wide angle specular reflection coefficients obtained by tank experiments are compared with various models. An anomalous postcritical acoustic penetration was observed experimentally. In th models, the sea bottom is successively considered as an attenuating fluid, a viscoelastic solid, and finally a poroviscoelastic medium. Applicability of these theories to sediments in the surf and nearshore zones was verified through the laboratory experiments in the sediment by measuring reflection coefficients at 500 kHz and inverting them into physical properties and sound speed and attenuation, revealing the nature of the material of the bottom and allowing comparison. An assessment of their validity is discussed, concluding that the Biot poroviscoelastic theory is the best to model the non random acoustic and physical properties of the sediment.
High frequency acoustic wave reflection on the surf zone seafloor
Die hochfrequente Schallwellenreflexion am Offshore-Meeresboden
Acustica ; 85 , 5 ; 701-706
1999
6 Seiten, 6 Bilder, 6 Tabellen, 8 Quellen
Article (Journal)
English
Meeresboden , Offshore-Gebiet , Schallwelle , Schallausbreitung , Sonar-Technik , Hochfrequenz , spiegelnde Reflexion , Einfallswinkel , Rechenmodell , Reflexionskoeffizient , Methodenvergleich , Schalldämpfung , Viskoelastizität , poröser Feststoff , Sediment , analytische Untersuchung , Verifikation
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