Acoustic analysis: configuration of absorber elements (CAABSF/PAABSF), excitation by a plane wave

Hi,

 

currently I am working on an acoustic analysis and I have some questions. I'd appreciate it if someone could answer them.

 

1) Absorber elements: I use CAABSF elements for absorption. How do I have to configurate the property PAABSF? The online help says the real part of the impedance should be equal to 'density multiplied with speed of sound' for each frequency. I set the imaginary part to zero. For the parameters S, A, B and K I didn't set any values. For 'RHOC' I entered the same value as for the real part of the impedance.

 

Is this correct? I don't want there to be any reflections, the elements should absorb everything. I didn't find any information for the imaginary part, S, A, B, K and RHOC.

 

2) For excitation I chose an acoustic source (ACSRCE). This is a sphere. Is there any possibility to define a plane wave (with an angle of choise) for excitation?

 

Pascal