Enhancing Noise Control System Design with Precise Flow Resistivity Estimation in Multilayer Porous Materials

Abstract

Abstract This paper presents a computational technique for estimating the equivalent flow resistivity in multilayer rigid porous materials, specifically for use in acoustic insulation systems. Existing models can predict sound transmission through individual layers, but lack a direct analytical link between the flow resistivity of multilayer materials and the properties of individual layers. To remedy this, the study makes use of equivalent fluid theory, which takes into account visco-inertial interactions between the material structure and the interstitial fluid. By establishing simplified expressions for the transmission coefficient of a bilayer medium under low-frequency Darcy conditions, the paper proposes a unique estimation approach. In addition, it derives a succinct law relating the resistivity of the bilayer medium to the resistivity and thickness of each layer, which extends to multilayer configurations. Experimental validation with bilayer samples demonstrates substantial agreement between the equivalent flux resistivity obtained directly and the theoretically predicted values, with relative errors ranging from 3–18%. The importance of the paper lies in its practical impact on acoustic insulation systems, for which accurate predictions of acoustic performance are crucial. The research proposes an efficient and reliable method for estimating equivalent flow resistivity, offering an alternative to labor-intensive experimental techniques and software. This contributes to acoustics by enabling accurate prediction and characterization of the acoustic properties of multilayer porous materials, facilitating the design of effective noise control systems.