The Linearized Potential Flow, Boundary Mode (lpfbm) 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 a stationary background compressible potential mean-flow. The interface performs a boundary mode analysis on a boundary, inlet, or cross section of the waveguide. The interface exists in 3D and 2D axisymmetric geometries and applies to boundaries. This study is used, for example, when computing and specifying the modes at a
Port condition in
The Linearized Potential Flow, Frequency Domain Interface. The physics interface solves an eigenvalue equation on boundaries, searching for the out-of-plane wave numbers at a given frequency.
When this physics interface is added, these default nodes are also added to the Model Builder —
Linearized Potential Flow Model,
Sound Hard Boundary (Wall), and
Initial Values. For 2D axisymmetric models 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 Potential Flow, Boundary Mode to select physics features from the context menu.
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
lpfbm.
For 2D axisymmetric components, the Azimuthal mode number m (dimensionless) is 0 by default. It is an integer entering the axisymmetric expression for the velocity potential:
The settings are the same as Sound Pressure Level Settings for the Pressure Acoustics, Frequency Domain interface.
This physics interface defines one dependent variable (field), the Velocity potential phi. The name can be changed but the names of fields and dependent variables must be unique within a model.
