Home / Examples / Acoustic Analysis [Mach] / Example 7: Acoustic Impedance

Example 7: Acoustic Impedance

 

General

 

• Acoustic impedance boundary condition is used to create a non-reflecting boundary.
   

• Unless specified in the list below, the default conditions will be applied.
   

• Obtain this session's project file. (Right-click and choose 'Save link as')




• Results will vary depending on Femtet version and the PC environment.

 

Analysis Space

Item	Settings
Analysis Space	3D
Model Unit	mm

 

 

Analysis Conditions

Item	Settings
Solver	Acoustic Analysis [Mach]
Analysis Type	Harmonic Analysis
Options	N/A

 

 

Tab	Setting Item	Settings
Harmonic Analysis	Frequency	50 [kHz]

Model

A vertical pipe is jointed on a horizontal pipe. Sound waves go in the vertical pipe and exit through the horizontal pipe.

The acoustic impedance boundary is set on the sections of the horizontal pipe.

That makes the horizontal pipe reflection-free.

 

 

 

Body Attributes and Materials

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

* Available from the material DB

 

Boundary Conditions

Boundary Condition Name/Topology	Tab	Boundary Condition Type	Settings
Vel/Face	Acoustic	Speed	1 [m/s]
Imp/Face	Acoustic	Acoustic Impedance	409.7 [Pa*s/m] (*)

(*) Set the specific acoustic impedance of air.

 

Results

The isosurface contour of the sound pressure is shown below.

 

 

Create the animation to see the sound waves flow better.