The Linearized Navier–Stokes, Boundary Mode Interface
The Linearized Navier–Stokes, Boundary Mode (lnsbm) interface (), found under the Acoustics>Aeroacoustics branch () when adding a physics interface, is used to compute and identify propagating and nonpropagating modes in waveguides and ducts in the presence of any stationary isothermal or nonisothermal background mean-flow. The interface performs a boundary mode analysis on a boundary, inlet, or cross section of the waveguide. The interface considers all thermal and viscous loss effects and the interaction with the background flow. This includes the acoustic boundary layer losses, if necessary. The interface exists in 3D and 2D axisymmetric geometries and applies to boundaries.
The interface solves for the acoustic variations of pressure, velocity, and temperature, as well as the out-of-plane wave number of the modes. The Linearized Navier-Stokes, Boundary Mode interface is, for example, used when setting up sources in waveguide systems in the presence of a background mean-flow. The background flow is assumed to be uniform in the propagation direction.
When this physics interface is added, these default nodes are also added to the Model BuilderLinearized Navier–Stokes Model, Wall, and Initial Values. For 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 Linearized Navier–Stokes, Boundary Mode to select physics features from the context menu.
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 lnsbm.