The Poroelastic Waves Interface
The Poroelastic Waves (pelw) interface (), found under the Acoustics > Elastic Waves branch () when adding a physics interface, is used to compute the displacement field and acoustic pressure fluctuation in porous materials with propagating poroelastic waves using Biot’s mixed p-u formulation. Dedicated Multiphysics Couplings exist that define the couplings between fluid, solid, and porous domains. Anisotropic poroelastic properties can be modeled using the Anisotropic Poroelastic Material material model.
Examples of applications include the propagation of elastic waves in rocks and soils, modeling the acoustic attenuation properties of particulate filters, characterizing sound absorbers and liners, and modeling the porous foams in headphones.
The physics interface is valid for modeling the propagation of the coupled linear elastic and linear acoustic waves in the frequency domain. Harmonic variation of the pressure, displacement field, and sources is assumed and given by eiωt, that is, using the +iω convention. Biot’s equations are solved accounting for the coupled propagation of elastic waves in the elastic porous matrix and pressure waves in the saturating pore fluid. This includes the damping effect of the pore fluid due to the combined effect of viscous and thermal losses (the Biot–Allard option where the poroacoustic properties are described by the JCA model), typically when the saturating fluid is air. An option also exists for liquids where only the viscous losses are important (the classical Biot loss model), this is typically with a saturating liquid like water or oil. The interface includes options for modeling both isotropic and anisotropic porous materials.
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For information about modeling strategies and meshing see Meshing Poroelastic Waves Models and Solving Large Poroelastic Wave Models in the Modeling with the Elastic Waves Branch section.
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See the Theory for the Poroelastic Waves Interfaces for details about the governing equations. The specifics of the Biot and the Biot–Allard models are also discussed here.
The boundary conditions are organizes such that conditions that apply to both the pressure field in the saturating fluid and the displacement field in the porous matrix are located in the main menu, while conditions that apply only to the porous matrix are in the Porous Matrix Conditions submenu, and conditions that apply to the saturating fluid are in the Fluid Conditions submenu. The latter two types of conditions can be combined on the same boundary.
When the Poroelastic Waves interface is added, these default nodes are also added to the Model Builder: Poroelastic Material, Impervious Layer, Free, and Initial Values. For 2D axisymmetric components, an Axial Symmetry node is also added.
Then, from the Physics toolbar, add other nodes that implement, for example, boundary conditions and sources. You can also right-click Poroelastic Waves to select physics features from the context menu.
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Acoustics of a Particulate-Filter-Like System: Application Library path Acoustics_Module/Automotive/acoustics_particulate_filter
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Acoustic Reflections off a Water–Sediment Interface: Application Library path Acoustics_Module/Underwater_Acoustics/reflections_water_sediment
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Headphone on an Artificial Ear: Application Library path Acoustics_Module/Electroacoustic_Transducers/headphone_artificial_ear
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Transverse Isotropic Porous Layer: Application Library path Acoustics_Module/Building_and_Room_Acoustics/transverse_isotropic_porous_layer
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Anisotropic Porous Absorber: Application Library path Acoustics_Module/Building_and_Room_Acoustics/anisotropic_porous_absorber
Settings
The Label is the default physics interface name.
The Name is used primarily as a scope prefix for variables defined by the physics interface. Refer to such physics interface variables in expressions using the pattern <name>.<variable_name>. In order to distinguish between variables belonging to different physics interfaces, the name string must be unique. Only letters, numbers, and underscores (_) are permitted in the Name field. The first character must be a letter.
The default Name (for the first physics interface in the model) is pelw.
The rest of the physics interface settings sections are the same as for The Pressure Acoustics, Frequency Domain Interface and The Solid Mechanics Interface.