Point sources of acoustic waves situated on material interfaces in fluid inhomogeneous, non-moving, non-dissipative media are studied. Two types of point sources are considered, namely the volume injection point sources, and volume force point sources. The volume injection point sources correspond to the local violation of constitutive relation. The reciprocity relations by Fokkema and van den Berg are used to prove that the acoustic pressure wave field at any point of the medium does not change when the volume-injection point source crosses a material interface. This general property of volume injection point sources at material interfaces is verified on the analytical ray-theory expressions for pressure wave field in fluid containing interfaces. The results obtained for the acoustic wave fields in fluid media allow also to make certain conclusions for strain-glut and stress-glut point sources at material interfaces in elastic isotropic and anisotropic media.
Acoustic waves, reciprocity relations, point sources at interfaces, stress glut, strain glut
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