In the following some animations showcasing the main damping mechanism occuring at acoustics liners are presented.

The first pair of animations below shows the linear momentum field ρu. The periodic hydrodynamic fluctuations through the orfice caused by the interaction with the acoustic pressure field are apparent. At the lower excitation amplitude the liner behaviour is already starting to involve nonlinear effects. The linear regime can also be educted from the reflection- and absorption behaviour in the parameter study. At the higher excitiation amplitude strong nonlinear effects are already present.

Momentum ρu - 130 dB

Momentum ρu - 140 dB

The second pair of animations below shows the magnitude of the voritcity field ω. The higher amplitude forcing causes extensive vortex shedding. The oscillating pressure field causes some vortices to be sucted back into the orfice leading to complex behaviour.

Vorticity mag ω - 130 dB

Vorticity mag ω - 140 dB

As a validation test of the characteristic boundary conditions the following animation shows a non-reflecting boundary condition subjected to plane wave radition: