Prediction of longitudinal disturbances in a multimode cylindrical waveguide

Axisymmetric waves in thick, solid, cylindrical waveguides are used in a number of engineering applications. Most important, these waves are employed to determine the modulus of materials at high temperatures. The description of the experiment typically uses plane waves to explain the results. Since a plane wave model of the experiment neglects dispersion, the accuracy of the measurement may be limited. In addition, care must be taken to use particular waveguide diameter to wavelength ratios to limit the error. An application of the Pochhammer-Chree solution to predict multimode wave propagation in a cylinder is described. This simple solution can be used to predict the time delay from experimental results while explicitly including the effects of dispersion. Application of this method to interpret experimental results may improve measurement accuracy. Use of this method with suitable signal processing will also make it possible to employ waveguides for which the diameter to wavelength ratio is constrained.