Hello there,

I have been trying to understand the influence of shell thickness for the axisymmetric acoustic element identified in the Abaqus benchmark study 1.11.4, Acoustic-structural interaction in an infinte medium. 

In the case study input file acoustic_bc_3dref.inp,  ACAX4 elements were applied to the acoustic region with a shell thickness of 0.1. My intuitive understanding is that since the element is axisymmetric (revolved around the Y-axis) then the acoustic pressure at the radiating boundary shouldn't make much of a difference when I change the shell thickness to 0.05 because it will still make a full revolution.

However, that assumption was quickly debunked and left me even more confused (see plots: purple represents a shell thickness of 0.1 and green represents a shell thickness of 0.05).

I would appreciate an explanation or discussion that can help clarify this concept.

Abaqus ​​​​​​​