An equivalent fluid model based finite-difference time-domain algorithm for sound propagation in porous material with...

Area of Science:

• Acoustics
• Materials Science
• Computational Physics

Background:

• Porous materials with rigid frames are widely used in sound absorption applications.
• Accurate simulation of their frequency-dependent acoustic properties is crucial for material design.
• Existing models may not fully capture the complex interplay of viscous and thermal effects.

Purpose of the Study:

• To develop a novel finite-difference time-domain (FDTD) algorithm for simulating the frequency characteristics of rigid-frame porous materials.
• To incorporate viscous and thermal effects into an equivalent fluid model for enhanced accuracy.
• To validate the proposed algorithm against experimental measurements.

Main Methods:

• An equivalent fluid model is employed, characterizing the porous material by frequency-dependent effective density and bulk modulus.
• These effective properties are represented as complex values using infinite impulse response (IIR) filters in the frequency domain.
• The Z-transform theory is utilized to discretize the frequency-domain wave equations for FDTD implementation.

Main Results:

• The proposed FDTD algorithm successfully simulates the frequency characteristics of porous materials.
• Calculated normal-incidence sound absorption coefficients show good agreement with measured data for multi-layered samples.
• The model effectively accounts for viscous and thermal effects, crucial for accurate acoustic predictions.

Conclusions:

• The developed equivalent fluid model based FDTD algorithm provides an accurate and efficient method for simulating porous materials.
• This approach is validated for predicting sound absorption coefficients over a broad frequency range.
• The algorithm offers a valuable tool for the design and analysis of acoustic materials.