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

Figure 7: Sensitivity of the shape factor ξ on the 1st and 2nd reflected waves in the low-frequency ultrasound regime f) Effect of Thermal Shape Factor ' on the Reflected Signal To investigate the impact of varying the thermal shape factor ξ ' on the 1st and 2nd high-frequency reflected waves, Figure 8 is presented. At an excitation frequency of 50 kHz, a +20% variation in ξ / ξ ' results in a +0.10% increase and a -1.91% attenuation in the amplitude of the 1st and 2nd reflected waves, respectively. This parameter exhibits a weak influence on the 1st reflected wave but a more significant effect on the 2nd reflected wave in the low-frequency ultrasound regime. Table 1 summarizes the effects of porosity, tortuosity, viscous and thermal characteristic lengths, as well as the two shape factors on the 1st and 2nd reflected waves in the low-frequency regime of ultrasound (50-120 kHz). Global Journal of Researches in Engineering Volume XxXIII Issue I Version I 40 Year 2023 © 2023 Global Journals ( ) I Investigating the Effects of Physical Parameters on First and Second Reflected Waves in Air-Saturated Porous Media under Low-Frequency Ultrasound Excitation