Acoustic Streaming from Thermoviscous Acoustics
The multiphysics interface Acoustic Streaming from Thermoviscous Acoustics couples the Thermoviscous Acoustics, Frequency Domain interface with a Laminar Flow interface. In the thermoviscous acoustic interface, the viscous and thermal boundary layers are resolved numerically and therefore their streaming contribution is part of the Acoustic Streaming Domain Coupling. Therefore, it is important that the mesh has a good resolution of the boundary layers.
The Acoustic Streaming Domain Coupling includes all the effects from the viscous stresses both in the boundary layers and in the domain of the fluid and is therefore often the dominant source of acoustic streaming when coupling from thermoviscous acoustics.
The Acoustic Streaming Boundary Coupling only contains the Stokes-slip contribution and is only important if the boundary of the fluid-solid interfaces is vibrating.
Note that the forces applied on the fluid flow rely on the gradients of the acoustic fields. Therefore, to obtain continuous and smooth derivatives, it is recommended to use a higher element order than the default setting for The Thermoviscous Acoustics, Frequency Domain Interface (see the Discretization section). It is recommended to use quadratic serendipity for the acoustic pressure and cubic serendipity for the acoustic velocity and temperature. This discretization is automatically set when adding the predefined multiphysics interfaces.