Learning Forum

[mattis.dahleriksson]

Hello,

I am trying to simulate wave propagation in a 3D geometry using the Coupled Field Transient module. Is there any way to include damping effects on the wave propagation? I have read through the theory guide as well as the forum on damping in acoustics, there are some information on viscous damping. I have tried to adjust the viscosity in engineering data but the acoustic body does not seem use that parameter at all.

BR

[Erik Kostson]

 

 

Hi

 

Yes viscosity (as given say in Eng. Data for Air and Water material ) provides attenuation, but can be hard to see for low frequencies and small propagation distances in gases.

 

Long time ago I looked into this and below is a summary:

 

 

 

[mattis.dahleriksson]

Hello,

Thank you for your reply. Yes, that was the post that i referred to. I have tried to replicate that simulation but i cannot reproduce the results. Can you provide some information regarding that particular model?

I have made a 10 m long water "duct" with 0.2x0.2 m2 cross section area using Fluid220 elements, a pressure pulse is applied on one end, a radiation boundary is applied at the other end. I am comparing the regular Water liquid material with 1.003e-09 MPa*s visc to an adjusted Water liquid with 0.001 MPa*s visc, but the acoustic pressure at the radation boundary is the same. 

My specific case involves a much slower pulses at 10-20 Hz, at a wave speed of 300 m/s. I want to benchmark my calculation against an analytical simulation that we have, the analytical simulation uses a specified damping ratio and i think this visc parameter could be a good parameter to work with.

BR