Lumped Port

The feature connects a waveguide or duct inlet/outlet to a lumped representation element. This can be an Electrical Circuit, a two-port network defined through a transfer matrix, or a lumped representation of a waveguide. Basically, it couples the end of a waveguide to an exterior system that has a given lumped representation. Several representations and sources exist to describe the lumped system as well as excite the system. When using the lumped port representation, it is assumed that only plane waves propagate in the acoustic waveguide.

Port Geometry

The settings in this section ensure that the correct port area (including symmetries) is used for computing important quantities like power, volume flow, and transfer matrix elements, associated with the port

Select the as (the default) or .

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When is selected, symmetry conditions adjacent to the port will automatically be taken into account if the is set to (the default); if set to enter the area multiplication factor Ascale manually.

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When is selected, the port will have the area of the selected boundaries, without taking any symmetry conditions into account.

Lumped Properties

Select the type of lumped representation connected to the port by selecting the as , (the default), or . The selection made here influences the settings and options in the section (see below).

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The option is used to connect the port boundary to a an Electrical Circuit interface (this requires the AC/DC module). The connection is set up by adding the element in the circuit model and selecting the lumped port as the , for example, . The feature automatically introduces a unit transformation from electric to acoustic units. The classical equivalence between the voltage V (SI units: V) and the pressure p (SI unit: Pa) as well as the current I (SI unit: A) and the volume velocity Q (SI unit: m3/s) is made.

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For the option it is assumed that the port boundary is connected to a two-port system described through a transfer matrix T. See the section for details.

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For the option it is assumed that the port boundary is extended with a waveguide of constant and identical cross section. The connection is equivalent to the two-port as the waveguide is defined through the appropriate transfer matrix T, of a waveguide. See the section for details.

For the and the options also select the as , (the default), , or . The selection made here influences what section is visible in the user interface. When is selected enter the , similar to the Port condition. See below for a description of the options.

Two electroacoustic tutorial models that couple a circuit (lumped representation of a microspeaker) to an acoustic domain using the and the option are:

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Lumped Receiver Connected to Test Setup with a 0.4-cc Coupler: Application Library path

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Lumped Receiver with Full Vibroacoustic Coupling: Application Library path

Connection Type

This section is visible if or is selected as the .

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For , select the as (the default) or . The selection indicates if the transfer matrix is from acoustic to acoustic variables or from electric to acoustic variables. The first can be used to include a transfer matrix of an acoustic subsystem, for example, extracted using the Port condition. The latter should, for example, be used if the transfer matrix represents a transducer with electric inputs and acoustic outputs.

Enter expressions, for example, calling interpolation functions that depend on frequency, for the elements of the transfer matrix T11, T12, T21, and T22.

For the option, you can choose to invert the transfer matrix (reverse its direction) by selecting . This option will invert and correct the signs of the transfer matrix T behind the scene.

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For , select the as (the default) or . The option will use the cross-section data and fluid properties of the boundary for the model. If is selected, enter values for the k, the Z. For both options, enter the L (SI unit: m) modeled with the lumped representation.


	The transfer matrix T couples the inlet (1) and outlet (2) pressure p and flow rate Q, defined in the feature, according to the following usual convention:

Source Settings

This section is visible if is selected as the .

Select the as (the default) or . Enter values for the average pressure pav,in or the volume flow Qin. These represent ideal sources equivalent to an ideal voltage or ideal current source.

Impedance Settings

This section is visible if is selected as the .

In this case, the lumped port is not active and an impedance condition can be applied to terminate the lumped representation. This could, for example, be the acoustic impedance of a microphone membrane. Select the as (the default), , or .

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For the option select the input format as an Zac (SI unit: kg/m4·s) or an Z (SI unit: Pa·s/m). If the electroacoustic representation is used for the two-port enter the Z (SI unit: Ω).

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The and options have the same options as the Impedance boundary condition.

Incident Mode Settings

This section is visible if is selected as the .

With this option the exterior behavior of the lumped system is like a Port condition with only plane wave modes propagating. The system can be excited if is turned . Enter the amplitude Ain and phase

of the incident wave. The units depend on the representation used. For this option, the scattering parameters acpr.S11, acpr.S21, and so on, of the system are also computed automatically.

Circuit

This section gives information about the state of coupling/connection to an Electrical Circuit interface. If the is not connected, the text text will be displayed. Once connected, a reference with a tag to the associated node, in the Electrical Circuit interface, is displayed.