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Sound Waves Directivity

The region outside the analysis model with an open boundary has no mesh. In the acoustic harmonic analysis, the sound pressure levels in the region are calculated and displayed

On the [Results] tab

click ▼ at the side of [Show Characteristics Chart] and select [Directivity Graph] on the submenu. The [Sound Waves Directivity] dialog box will appear.

Item

Notes

Graph Type

Either XY Graph or Polar Graph can be selected.

Observation Point

Specified by the distance and the angles.

See the figure at Coordinate system for the parameters definition.

The distance of the observation point is set by default.

It is either 100 times the wavelength or 10 times the analysis range, whichever the longer.

The observation point is required to be outside of the analysis domain.

The distance is measured from the origin of the coordinates of the open boundary.

φ, θ

Enter the min/max/number of divisions for φ and θ.

For example, if φ is in the range of 0-90 [deg] and the number of divisions is 3,

and θ is in the range of 0-90 [deg] and the number of divisions is 10, there will be 4 series of graphs:

Series 1; φ: 0 [deg], θ: 0-90 [deg]

Series 2; φ: 30 [deg], θ: 0-90 [deg]

Series 3; φ: 60 [deg], θ: 0-90 [deg]

Series 4; φ: 90 [deg], θ: 0-90 [deg]

Display

Selectable from real part, imaginary part, sound pressure level, and A-weighted sound pressure level.

Plane of Symmetry

Specified to create a half, quarter, or 1/8 model.

For example, select XY plane for the model created in the +Z axis area.

[Setting] - [Horizontal axis]

Selectable from θ or φ for the horizontal axis of XY graph and the angle component of the polar graph.

Create display data

Selectable from Polar Graph and XY Graph.

It might take a while to create the data. To abort it, press the <ESC> key.

Caution

The settings for the items other than the modes and the observation points will be saved for the next operation.

The modes and the observation points will not be saved as they depend on the model and the analysis.

Sound wave directivity is calculated using the Kirchhoff integral theorem. The theoretical equation is as follows.