Measuring flow resistivity of porous material via acoustic reflected waves

2005 ◽  
Vol 98 (8) ◽  
pp. 084901 ◽  
Author(s):  
N. Sebaa ◽  
Z. E. A. Fellah ◽  
M. Fellah ◽  
W. Lauriks ◽  
C. Depollier
Keyword(s):  
Porous Material ◽  
Reflected Waves ◽  
Flow Resistivity

scholarly journals Inverse Measurement of the Thickness and Flow Resistivity of Porous Materials via Reflected Low Frequency Waves-Frequency Approach

2021 ◽  
Author(s):  
Mustapha Sadouki
Keyword(s):  
Reflection Coefficient ◽  
Direct Problem ◽  
Fluid Model ◽  
Low Frequency ◽  
Low Frequencies ◽  
Reflected Waves ◽  
Two Samples ◽  
Flow Resistivity ◽  
Theoretical Reflection ◽  
Low Frequency Waves

A direct and inverse method is proposed for measuring the thickness and flow resistivity of a rigid air-saturated porous material using acoustic reflected waves at low frequency. The equivalent fluid model is considered. The interactions between the structure and the fluid are taken by the dynamic tortuosity of the medium introduced by Johnson et al. and the dynamic compressibility of the air introduced by Allard. A simplified expression of the reflection coefficient is obtained at very low frequencies domain (Darcy’s regime). This expression depends only on the thickness and flow resistivity of the porous medium. The simulated reflected signal of the direct problem is obtained by the product of the experimental incident signal and the theoretical reflection coefficient. The inverse problem is solved numerically by minimizing between simulated and experimental reflected signals. The tests are carried out using two samples of polyurethane plastic foam with different thicknesses and resistivity. The inverted values of thickness and flow resistivity are compared with those obtained by conventional methods giving good results.

scholarly journals Experimental measurement of the porosity and the viscous tortuosity of rigid porous material in low frequency

2018 ◽  
Vol 37 (2) ◽  
pp. 385-393 ◽  
Author(s):  
M Sadouki
Keyword(s):  
Porous Material ◽  
Acoustic Pulse ◽  
Low Frequency ◽  
Acoustic Method ◽  
Simple Relation ◽  
Low Frequencies ◽  
Reflected Waves ◽  
Rigid Frame ◽  
Temporal Model ◽  
Low Frequency Waves

In this paper, an acoustic method is presented for measuring the porosity and the viscous tortuosity of air-saturated-porous materials at low frequencies. The proposed method is based on a temporal model of the direct and inverse problem for the reflection of low-frequency waves by homogeneous isotropic slab of porous material having a rigid frame. Reflected coefficient for a slab of porous material is derived from the responses of the medium to an incident acoustic pulse where a simple relation between flow resistivity, porosity, viscous tortuosity and the reflected waves is obtained. A numerical method and efficient tool for the estimation of the porosity and the viscous tortuosity are presented and discussed.

Modelling of Rigid-Frame Porous Materials: A Simple Approach

2000 ◽  
Author(s):  
M. J. Brennan ◽  
W. M. To
Keyword(s):  
Porous Material ◽  
Porous Materials ◽  
Characteristic Impedance ◽  
Simple Approach ◽  
Middle Ground ◽  
Acoustic Behaviour ◽  
Rigid Frame ◽  
Flow Resistivity ◽  
Stiffness And Damping ◽  
Optimum Flow

Abstract This paper is concerned with the modelling of rigid-frame porous materials. Currently there are very simple models which describe the acoustic behaviour of such materials, and there are also very complicated models. The aim of this paper is to present a model which occupies the “middle ground”, but is simple enough to be used by practising noise control engineers. Using concepts of acoustic mass, stiffness and damping, non-dimensional expressions for the acoustic wavenumber and the characteristic impedance of a rigid-frame porous material are derived. These expressions are used to give a “rule of thumb” for the optimum flow resistivity for a given thickness of material.

scholarly journals MEASUREMENT OF FLOW RESISTIVITY USING COMPUTATIONAL FLUID DYNAMICS

2020 ◽  
Author(s):  
Aamir Khan ◽  
S. Jeyanthi ◽  
Hemantika Aggarwal ◽  
Karanbir Singh ◽  
Robin Kumar ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Porous Material ◽  
Polyurethane Foam ◽  
Pressure Measurement ◽  
Fibrous Material ◽  
Acoustic Behavior ◽  
Fibrous Materials ◽  
Flow Resistivity ◽  
Industrial Context

Flow resistivity is one of the most important parameters used to describe the acoustic behavior of fibrous materials, as porosity is highly used in industrial context, this paper summarizes the simulation of finding the flow resistivity using computational fluid dynamics and minimizing the error between calculated and measured resistivity.The estimation is made by taking Polyurethane Foam as sample fibrous material and varying porosity from 0.70 up to 0.98. The CFD tool analyzes and computes different pressure value respectively. Flow resistivity is further verified using experimental execution in which flow resistivity is measured from pressure measurement on a sample of porous material

Random pseudo promptings applied to the thermal characterization of a wet porous material

1999 ◽  
Vol 6 (1) ◽  
pp. 101-108 ◽  
Author(s):  
E. Delacre ◽  
D. Defer ◽  
E. Antczak ◽  
B. Duthoit
Keyword(s):  
Porous Material ◽  
Thermal Characterization

Porous material composites produced by combustion synthesis

1999 ◽  
Author(s):  
X. Zhang ◽  
J. Moore ◽  
F. Schowengerdt ◽  
H. Yi
Keyword(s):  
Porous Material ◽  
Combustion Synthesis
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