Acoustic Streaming from Pressure Acoustics
The multiphysics interface Acoustic Streaming from Pressure Acoustics couples the Pressure Acoustics, Frequency Domain interface with a Laminar Flow interface. The multiphysics interface is appropriate to use when either:
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The viscous boundary layers thickness is a lot smaller than the acoustic wavelength and the geometrical length scales of the system.
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The contribution from the viscous boundary layers can be neglected.
The Acoustic Streaming Domain Coupling includes the bulk contributions to the acoustic streaming field, but importantly not the contribution from the viscous boundary layers. This is different from the coupling from thermoviscous acoustics. So the domain coupling includes the sources that result in Eckart streaming and thermoacoustic streaming. It is recommended to use the Thermally Conducting and/or Viscous Fluid Model in the pressure acoustics interface to capture all losses. This fluid model is automatically selected when adding the predefined multiphysics interface.
The Acoustic Streaming Boundary Coupling includes the contributions from the viscous boundary layers and the Stokes slip due to vibrations of the boundary. Thus, the Acoustic Streaming Boundary Coupling contains the sources that result in traditional Rayleigh streaming. The effects from the viscous boundary layers are included in the slip velocity set by the boundary coupling. It is therefore necessary to use the Thermoviscous Boundary Layer Impedance condition in the The Pressure Acoustics, Frequency Domain Interface, so that the correct boundary losses are included in the acoustic model. The Thermoviscous Boundary Layer Impedance boundary condition is automatically added when adding the predefined multiphysics interface.