Reflection and transmission of transient ultrasonic wave in fractal porous material: Application of fractional calculus

Abstract

This paper provides a time domain model for the propagation of transient ultrasonic waves in a self-similar porous material having a rigid frame. This model is based on the formalism of Stillinger–Palmer–Stavrinou, which consists in modeling the fractal material as a porous medium with a non-integer dimensional space. This paper is devoted to the time-domain analytical calculus of the reflection and transmission operators that are expressed in terms of Mittag-Leffler functions. A sensitivity numerical study using ultrasonic reflected and transmitted waves is performed, highlighting the effect of the material’s physical parameters (fractal dimension, tortuosity, viscous characteristic length and porosity) on the waveforms.