Reflection of narrow ultrasonic beams at fluid/solid interfaces

Abstract

The reflection of ultrasonic beams near the Rayleigh angle for a fluid/solid interface is a well researched subject. Existing theories, however, are all approximate with limitations such as beamwidth large compared to the wavelength, lossless media, parallel beams of particular shape (Gaussian), etc. A new numerical model has been developed to solve the reflection problem without any of the above limitations. This technique is based on the fast-field solution to the wave equation, and solutions can now be obtained for any beamwidth, and for parallel, diverging, and converging beams. Furthermore, due to the numerical efficiency of the computer code, pulsed-beam solutions can be generated in reasonable time using Fourier synthesis of the time signals. Computational results are presented for various beam configurations reflected at water/steel and water/aluminum oxide interfaces, and the results are compared with available experimental data.