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

Figure 6: The sensitivity of the thermal characteristic length on the 1st and 2nd reflected waves for a frequency of 50 kHz e) Effect of Viscous Shape Factor on the Reflected Signal The sensitivity of the shape factor ξ on the 1st and 2nd reflected waves in the Low-Frequency Ultrasound regime is presented in Figure 7. According to this figure, a -20% variation of ξ results in a regression of -0.26% and -4.89% in the amplitude of the 1st and 2nd reflected waves, respectively. For a variation of +20% of ξ , we observe a growth of +0.17% and 3.29% in the amplitude of the 1st and 2nd reflected waves. It can be concluded that the shape factor ξ has a weak influence on the first reflected wave but a strong sensitivity on the second wave in the low-frequency range of ultrasound. Moreover, the variation decreases for the first reflected wave and increases for the second wave as the frequency increases. © 2023 Global Journals Global Journal of Researches in Engineering Volume XxXIII Issue I Version I 39 Year 2023 ( ) I Investigating the Effects of Physical Parameters on First and Second Reflected Waves in Air-Saturated Porous Media under Low-Frequency Ultrasound Excitation