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

Figure 3: Sensitivity of porosity ϕ on the 1st and 2nd reflected signals at 50 kHz Figure 4: Sensitivity of Tortuosity ∞ on the 1st and 2nd Reflected Waves © 2023 Global Journals Global Journal of Researches in Engineering Volume XxXIII Issue I Version I 37 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 b) Effect of Tortuosity ∞ on the Reflected Signal Figure 4 illustrates the sensitivity of tortuosity ∞ on the 1st and 2nd reflected waves, for an excitation pulse of frequency 50 kHz. When the initial tortuosity value is increased by +20%, the amplitude of the 1st and 2nd reflected waves increases by +33.16% and 10.82%, respectively. Conversely, a decrease of -20% in tortuosity results in a decrease in the amplitude of the 1st and 2nd reflected waves by -40.98% and -27.47%, respectively. Notably, the impact of tortuosity is more pronounced on the 1st reflected signal than on the 2nd. Additionally, the sensitivity of tortuosity to the reflected signal increases with frequency, as detailed in Table 1.