Modelling the emergence of the coherent field for cavities in a solid matrix

Valerie Pinfield , Richard Challis

What is the acoustic field reflected from a region of spherical cavities distributed in a solid medium? The question has application in the field of non-destructive testing of composite materials, in which porosity is present. Whilst the most common solution would be to model the coherent field, is this necessarily a valid description for a finite region with a particular fixed set of cavity locations? The coherent field emerges only after taking an ensemble average over all possible scatterer locations. A semi-analytical model of the scattered field from a region of spherical scatterers was used to determine the conditions under which the coherent field is representative of that reflected by a single realisation of scatterer locations. A set of simulations was carried out for single realisations of randomly-generated cavity positions, using a far-field scattering amplitude in the long-wavelength limit to define the scattered field arriving at a receiving device. Comparison with the corresponding coherent field, representing the ensemble-average result, shows the conditions in which the coherent field can be applied to the field reflected from such materials.

Domaines: Acoustique [physics.class-ph]

Valerie Pinfield, Richard Challis. Modelling the emergence of the coherent field for cavities in a solid matrix. Acoustics 2012, Apr 2012, Nantes, France. ⟨hal-00810722⟩