Example1 Radiation Impedance of Disc

A vibrating disc is placed in the air. The sound waves generated by it are analyzed.
The sound power, the radiation impedance and the sound pressure distribution for each frequency are solved.
Unless specified in the list below, the default conditions will be applied.

The harmonic analysis tab is set up as follows.

The sound waves propagate outside the analysis region. Therefore the “open boundary” condition below is applied initially.

Tabs	Setting Item	Settings
Harmonic analysis	Frequency	Minimum: 200[Hz] Maximum: 3000[Hz]
	Sweep Type	Select Linear step by division number. Division number: 20
	Sweep Setting	Select Fast sweep. Tolerance: 1.0×10^-2
Open Boundary Tab	Type	Absorbing boundary
	Order of Absorbing Boundary	1st degree
	Coordinates of Origin	x = y = z = 0

The air hemisphere is created from a solid body. The open boundary is set on the surface of the hemisphere.

A circular sheet body is defined for imprinting.
Its boundary condition type is speed.

The hemispheric solid body is created. The material is air.

The “speed” boundary condition is set on the circular face topology, which is created by segmenting the circular sheet body.

Body Number/Type	Body Attribute Name	Material Name
0/Solid	Air	000_Air(*)

* Available from the Material DB

The “speed” boundary condition is set on the face of the imprinting body.

Boundary Condition Name/Topology	Tab	Boundary Condition Type	Settings
Open/Face	Acoustic	Open boundary
V0/Face	Acoustic	Speed	1[m/s]

To see the calculated characteristics, go to the [Results] tab,

click [Table] .

The table below shows the power.

Other characteristics can be seen on other tabs.

The gradation contour of the sound pressure at 200[Hz]

The gradation contour of the sound pressure at 900[Hz]

The gradation contour of the sound pressure at 2020[Hz]

The gradation contour of the sound pressure at 3000[Hz]

The sound pressure varies as the drive frequency changes.