Axisymmetric wave dispersion in outside traction-free fluid-filled cylindrical shells

In order to develop a kind of standard scale pits, studies on acoustic wavefield in outside traction-free fluid-filled cylindrical borehole are necessary. This article will calculate and analyze the dispersive characteristics of the symmetric mode wave in the cylindrical waveguide structure. Numerical results show that, the dispersive curves of the outside traction-free fluid-filled cylindrical shells are the coupled dispersive curves of the cylindrical shell in vacuum and the fluid cylinder. The factors influencing the dispersive characteristics of the cylindrical shell in vacuum and the fluid cylinder influence the dispersive characteristics of the outside traction-free fluid-filled cylindrical shell in the same way. This work provides some basic theory for the construction of a new kind of standard scale pits.