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

Investigating the Effects of Physical Parameters on First and Second Reflected Waves in Air-Saturated Porous Media under Low-Frequency Ultrasound Excitation Mustapha Sadouki α & Abd El Madjid Mahiou σ Abstract- This simulation study investigates the impact of a 20% variation in physical parameters, including porosity, tortuosity, viscous and thermal characteristic lengths, and two newly introduced viscous and thermal shape factor parameters, on reflected waves at the first and second interfaces in air-saturated porous media under low-frequency ultrasound excitation. The acoustic behavior of air-saturated porous media is modeled using the equivalent fluid theory and the Johnson-Allard model, refined by Sadouki [Phys. Fluids 33, (2021)]. Our results demonstrate that a 20% variation in certain physical parameters significantly affects the reflected waves at the first and second interfaces in the low-frequency domain of ultrasound. This study enhances our understanding of the underlying mechanisms governing acoustic wave propagation in air-saturated porous media, which is valuable for optimizing ultrasound-based techniques in a range of applications, such as nondestructive testing, medical imaging, and noise pollution control in buildings, aircraft, automobile industry, and civil engineering sectors. Keywords: air-saturated porous media, ultrasound, physical parameters, reflected waves, simulation study, equivalent fluid theory, Johnson-Allard model. I. I ntroduction orous materials have a rich history that dates back to ancient times, and they continue to be of great importance in modern chemistry and materials science [1]. These materials exhibit unique properties that make them valuable across a wide range of applications, including biomedical, building and construction, aerospace, and environmental domains. Their diverse classifications, such as fibrous, granular agglomerates, polymeric, and construction materials, contribute to their widespread use in our daily lives. In recent years, there has been a growing interest in the use of porous materials due to their versatility and unique properties. For example, in the biomedical field [2], porous materials have shown tremendous potential for drug delivery and tissue engineering. The porous structure of these materials Author α : Acoustics and Civil Engineering Laboratory. Khemis-Miliana University. Ain Defla, Algeria. e-mail: mustapha.sadouki@univ-dbkm.dz Author σ : Acoustics and Civil Engineering Laboratory. Khemis-Miliana University. Ain Defla, Algeria. Theoretical Physics and Radiation Matter Interaction Laboratory, Soumaa, Blida, Algeria. allows for controlled drug release and promotes cell growth, making them ideal candidates for advanced medical applications. In the building and construction industry [3], porous materials are commonly used for insulation and soundproofing. Their ability to absorb sound waves through viscous friction and thermal exchanges makes them an excellent choice for reducing noise pollution. Similarly, in the aerospace industry[4], porous materials are used for thermal insulation and noise reduction. The physical and mechanical parameters used to characterize the properties of porous materials include geometric tortuosity, viscous and thermal characteristic lengths [5-8], Young's modulus of elasticity, and Poisson's ratio. In the field of acoustics, porous materials are widely used to reduce noise pollution by absorbing a part of the sound waves through viscous friction and thermal exchanges [4]. Previous studies have been conducted to investigate the influence of physical parameters describing porous media on the transmitted signal in the low-frequency ultrasound regime [9-11]. However, there is a need for a more comprehensive numerical simulation study to determine the effect of physical parameters on the low- frequency ultrasonic signal reflected by the first and second interfaces of the medium. In this study, we address this gap by investigating the impact of a 20% variation in physical parameters, including porosity, tortuosity, viscous and thermal characteristic lengths, and two newly introduced viscous and thermal shape factor parameters, on the reflected waves at the first and second interfaces in air- saturated porous media in the low-frequency domain of ultrasound. The acoustic behavior of air-saturated porous media is modeled using the equivalent fluid theory and the Johnson-Allard model refined by Sadouki [12]. This study enhances our understanding of the underlying mechanisms governing acoustic wave propagation in porous media, providing valuable insights for optimizing ultrasound-based techniques in a range of applications, such as nondestructive testing, medical imaging, and noise pollution control in P © 2023 Global Journals Global Journal of Researches in Engineering Volume XxXIII Issue I Version I 33 Year 2023 ( ) I