Ultrasonic Field Modeling of Transient Wave Propagation in Homogenous and Non-Homogenous Fluid Media Using Distributed Point Source Method

Abstract

In the field of nondestructive evaluation (NDE), the newly developed distributed point source method (DPSM) is gradually gaining popularity. DPSM is a semi-analytical technique used to calculate the ultrasonic fields (pressure, velocity and displacement fields) generated by ultrasonic transducers of finite dimension immersed in homogeneous or non-homogeneous media. In this report the technique is extended to model the propagation of transient wave and its pressure tomo-grams generated both in homogeneous fluid and non-homogeneous fluid having single interface. Tone burst signal is used as input signal at one end of fluid and reflected as well as transmitted pulse is observed at various points. In the first case DPSM model for homogeneous fluids is developed and results are validated for closed form solutions. In the second case, interface of two fluids is kept perpendicular to wave propagation direction and wave propagation is studied at various points. In both cases, Fast Fourier transformation (FFT) is used convert time domain signal into frequency domain and inverse FFT is used to again transform results in time domain. Numerical results obtained from DPSM model are compared with experimental results taken from the experimental setup on different fluids and the time-histories are found to be matching with reasonable accuracy.