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Connection between the dynamic bulk modulus of air in a porous medium and the specific surface
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1995
Year
EngineeringSpecific SurfaceFluid MechanicsMechanical EngineeringGranular MediumPorous MediumPorous BodyVibrationsFluid PropertiesDynamic Bulk ModuliPhysical AcousticNumerical SimulationAcoustic MaterialTransport PhenomenaDynamic Bulk ModulusThermodynamicsSound PropagationBulk ModuliMaterials ScienceAcoustic PropagationMultiphase FlowUltrasoundHeat TransferPore StructurePorothermoelasticityFluid-solid InteractionPorosityThermal Engineering
A model for the prediction of the frequency dependence of the dynamic bulk modulus of air in a porous medium with one parameter, the thermal characteristic dimension Λ′, was proposed previously by one of the authors. This parameter depends only on the porosity and the area of the surface of porous frame in contact with the air in the material. This area can be evaluated with the standard Brunauer, Emmett, and Teller (BET) method, from krypton adsorption by the frame at liquid–nitrogen temperature. Comparisons between acoustically measured bulk moduli and predictions obtained with values of Λ′ evaluated with the BET method are presented. The BET results provide reasonable agreement with acoustic measurements of thermal dimensions and dynamic bulk moduli.