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ISSN Druckformat: 1091-028X
ISSN Online: 1934-0508
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SOUND WAVES PROPAGATION WITHIN POROUS LAYERS USING FORCHHEIMER'S MODEL
ABSTRAKT
A fully nonlinear wave analysis is performed for an acoustic wave which propagates through an isentropic porous medium under the boundary layer approximations. It is found that the main three parameters that govern the propagation process are reduced frequency parameter, Re = ρKω/µ; Forchheimer's number, Fr = a/√Kω; and porosity, ε. The propagation process takes place under isentropic conditions and the sound disturbance is under monofrequency and harmonic conditions. It is found that as porosity e is increased, the attenuations and phase shift for both forward and backward sound waves is decreased; this is due to unfavorable acoustic wave propagation in plain medium. The effect of increasing the reduced frequency number, Re, is found to decrease attenuation and increase phase shift velocities; this is also due to the movement of porous medium to the plain medium limit and due to low viscous damping effects. The effect of increasing Forchheimer's number is found to decrease attenuation and increase phase shift for both forward and backward sound waves.