Acoustics: "Sonar Listens to Material Properties"
Dr. Mario Zampolli, Dr. Alessandra Tesei, Dr. Gaetano Canepa and Dr. Finn Jensen - NATO Undersea Research Centre in La Spezia, Italy
During WWII, SONAR was used primarily to detect submarines; today these techniques are used to look for undersea objects such as shipwrecks and for measuring fish abundances and distributions.
SONAR has traditionally used frequencies for which the wavelengths are far smaller than the size of the objects being studied. This makes it possible to discriminate the shape of objects rather well, and leads to advanced applications such as underwater acoustic cameras. However, it is difficult to identify the material of an object using high-frequency signals. Thus researchers are turning their attention to low-frequency schemes.
With the help of COMSOL Multiphysics, Dr. Mario Zampolii and a group of researchers at the NATO Undersea Research Centre are studying how to use low-frequency echoes to determine what an object is made of. Yet, this requires some pretty sophisticated coupling of the equations describing the structural properties of the objects being investigated.