Global Journal of Researches in Engineering, I: Numerical Methods, Volume 23 Issue 1

© 2023 Global Journals Global Journal of Researches in Engineering Volume XxXIII Issue I Version I 35 Year 2023 ( ) I Figure 1: Problem geometry The continuity of the pressure and velocity fields at the medium boundary gives the reflection coefficient of the porous material [17]: = �1− � 2 � sinh � � � 2 � ℎ� � �+(1+ � 2 ) sinh � � � (4) Where � = 1 � ( ) ( ) is the normalized characteristic impedance of the material, ϕ is the porosity, and � = � 0 ( ) ( ) is the wave number of the acoustic wave in the porous medium. The incident and reflected fields and are related in the frequency domain by the reflection coefficient R: ( , ) = ( , ) (5) In the time domain, the reflected signal ( , ) is obtained by taking the inverse Fourier transform of Eq. (5): ( , ) = ℱ −1 � ( , )� (6) Investigating the Effects of Physical Parameters on First and Second Reflected Waves in Air-Saturated Porous Media under Low-Frequency Ultrasound Excitation